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The Dirt on Dirt - Clay

Clay soil is often cursed by gardeners but clay can be a wonderful thing. The Dirt on Dirt - Clay will teach you about clay soils, why you should love them, and how to make them even better.

Contributors: Dr. Rick Schoellhorn
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Clay soil is often cursed by gardeners but clay can be a wonderful thing. The Dirt on Dirt - Clay will teach you about clay soils, why you should love them, and how to make them even better.

Soil comes in a whole array of types.  The basic categories are clay, silt, loam and sand with constant variation within each of these classes.  If you have silt or loam soils you are sitting pretty, gardening will be easy and you will love your soil.  If you have clay or sandy soils it will take a bit more input from you before you love your soil.   Trust me, you can love your clay or sandy soil, it just takes a bit of knowledge and a bit of elbow grease.  How, exactly do you learn to love clay soil?  Read on to learn more about what clay soil is, why you should be glad you have it and how you can make it even better.

First things first, how do you know you have clay soil? Clay is often reddish in color, water usually is absorbed into clay more slowly, it has a tendency to dry slowly, to clump together (and not want to break apart), and to stick like mad to shoes and gardening implements.  It will also tend to crust over and crack when it gets dry.  Does this sound like the soil in your garden?  Then you probably have clay soil.  If you aren’t completely certain take a sample of your soil to your local garden center or Cooperative Extension office, they should be able to help you determine, for sure, if your soil is clay.

What is Clay Soil?

First off what does it mean that you have clay soil?  It means that the soil in your garden is composed of many tiny plate-like soil particles that can compact with time to form a hard, solid mass that makes shoveling difficult and digging holes a bit more laborious. Clay soils come in many types and it is always hard to know which kind you have without doing a soil test. Usually your local county extension service will help you in doing a basic soil test to let you know what particular type of clay soil you have.

What’s good about clay soil & what’s bad about it?

Let’s take a look at what a clay soil does for you, both the good and the bad.

First the good parts: A clay soil provides a lot of wonderful things for your garden. First off clay soils are more fertile than many other soil types; each tiny clay particle is packed with places to hold on to water and fertilizer (soil specialists call this CEC or Cation Exchange Capacity, it just means that clay soil can hold a lot of nutrients whereas a sandy soil cannot). So clay soils can save you on watering and reduce the number of times you have to fertilize. This is very important and most gardeners in clay soil are happy to have clay, once they learn how best to garden in clay soil.

Clay soils also provide a wonderful foundation for plants to get their roots into; a lot of perennials and annuals thrive in clay soils since they can get a firm grip on the soil with their roots. This firm grip allows them to survive extremes of temperature and moisture that plants in sandy soil cannot (with clay soil there is a minimum of heaving due to cycles of freezing and thawing, the plants are less likely to "jump" out of the ground). So with a clay soil you water less, fertilize less, get a better foundation for your plants and extend their hardiness when extremes in weather or other factors occur. I bet right now you are feeling a bit better about that clay soil you’ve been cursing!

A few bad things: So, it is likely obvious that a heavy clay soil is going to be more work to till or shovel than a sandy soil.  However, when you are planting a landscape most of the digging is only done once and then you get to reap all the benefits of clay soils for the rest of the life of the landscape. No doubt, a clay soil is heavier and more likely to compact than a sandy soil, but you do get a lot of benefits for your labor.

A clay soil can get very mucky if it is too wet.  If your clay soil is sticking to your shovel, stop working.  The soil is too wet to work with and you will compound the common problems of clay soil by working with it while it is wet.  Basically, your soil will be even more compacted after you are done digging.

Clay soil has all those nooks and crannies to hold water and fertilizer, which is great.  However, clay soils will hold tight to the bad things too, like salts.  Ridding clay soil of extra salt build up or changing the pH of the soil will be more difficult due to the gripping ability of soil particles that make up clay soil.   Clay soils latch on to all minerals and this can be good (fertilizer) and bad (salt). Should you have a problem clay soil, just know that it is generally a long term process to rehabilitate the soil but in the end, you will usually prevail.   

One last thing that might be a draw back to a clay soil is when you are in a boggy area, clay soils can limit the amount of air plant roots get when they are saturated, so if you have a boggy area select plants that tolerate this condition and watch out for plants that need lots of air around their roots when planting in clay soils.

How to fertilize clay soils most effectively – One of the things we all need to learn is how to avoid wasting fertilizers as they eventually run off into our lakes, streams and groundwater if we use them thoughtlessly. Clay soils are great 'nutrient' banks, so you do not need to fertilize as much and you’ll still have a nice garden. When you are gardening in clay it is fine to use liquid fertilizers, granular fertilizer, slow release fertilizers, and organic fertilizers (like fish emulsion).  Simply make sure that whatever fertilizer you choose, you use it responsibly.  One of the biggest pollutants in our steams and lakes is the run off from lawns in urban area where gardeners are using excess fertilizer and water to try to get the perfect lawn, it is not worth the cost.

Most landscapes and gardens need a liquid fertilizer about every 2 weeks, OR a granular fertilizer about every month, OR a slow release fertilizer 2-3 times per season. Over fertilizing is just wasting money and potentially damaging the environment. If you are one of those people who love to fertilize try using a liquid feed and just wetting the foliage of your plants, not soaking them. Plants can pick up a lot of nutrient right through their leaves and by doing this in small doses you are less likely to cause problems in your garden. Did you know that over-fertilized plants tend to be more susceptible to insect and disease problems?  This may seem counter-intuitive but over-fertilized plants tend to be really lush because they have been pushed to grow fast, this weakens the plants and makes them more susceptible to pests and disease

Because clay soils hold on to fertilizers well you should use a light hand when applying fertilizer.  Start out fertilizing at a slightly lower rate or waiting a bit longer than recommended between fertilizer applications.  If the plants remain healthy and happy you are fertilizing often enough.  If the leaves start to turn a yellow color you aren’t fertilizing quite enough.  Armed with this knowledge you should fertilize a bit more often or at a slightly stronger rate.  A bit of trial and error will tell you how often you need to fertilize with your specific soil.  That clay soil just might save you money due to lower fertilizer costs.  For more information on fertilizing click here.

How to water clay soils most effectively – Watering is the biggest challenge most gardeners’ face and most people over-water their plants, it is the single biggest cause of plants dying. Clay soil tends to hold water for long periods of time, therefore, if your garden soil is made up of clay, you should be watering less frequently. Spots in your yard that stay wet almost constantly are a sure sign you need to cut back on the amount of water you are applying. Check with your local county extension service to see what recommended watering rates are in your town.

Most landscapes and garden plants need to be watered just as plants are beginning to wilt a little, watering less frequently and more deeply will help develop deep root systems.  Frequent light watering encourages shallow roots which will make plants less drought tolerant. The best way to water is deeply and infrequently (except for recently planted flowers and landscapes, these need water frequently to get established). If you have a sprinkler system, make sure to check and see that it is not over-watering on a regular basis, plants will get used to whatever watering cycle you give them, so plants that are regularly overwatered are more likely to collapse when the water isn’t there, the reverse is also true, plants that have to work just a little bit in between watering are tougher and more likely to handle short dry periods.  For more on watering landscapes click here.

How to make clay soils better:

Incorporating compost – tired of chipping away at a clay soil that is hard and heavy? Try mixing in organic matter (compost, straw, fine wood bark, peat moss).  Adding these things to your soil will make it more difficult for the soil to clump together and harden. This is especially true around trees and shrubs.  In the garden a good compost to soil percentage can make digging a breeze and reduce the most common problems associated with clay soils.  Adding compost can also help, somewhat, with drainage,  keeps the soil for compacting which can block water flow – resulting in soils that remain wet and boggy. The compost will also act as a slow release fertilizer (it will container nitrogen and other nutrients) and as an additional way to hold water for your growing plants!  Click here to learn more about compost.

Does digging up an entire flower bed and incorporating compost sound too daunting?  While tackling an entire bed at once is the most efficient way of improving soils you can improve your soil a bit at a time.  One method for accomplishing this would be too improve each little spot where you are planting a plant.  To do this, dig a hole 2 to 3 times larger and deeper than what is necessary for the plant you are transplanting.  Incorporate a healthy dose of compost by mixing it in with the soil you dug out of the hole.  Fill some soil back into the hole, place your plant in the hole and then refill the rest of the hole with the compost enriched soil.  While the surrounding soil isn't enhanced the new plant is happily ensconced in good, compost rich soil.  Over several years you will gradually improve the soil in the entire bed.  This is also an effective way of improving soil in existing, already planted beds.

Mulching – Clay soils can tend to speed water runoff (water isn’t absorbed as quickly into clay soils as it is other soils) and certainly clay soils stick to the bottoms of your feet and make a mess when you go indoors. But you can solve these problems, and make the most of the positive properties of clay soil, by covering the exposed soil with a thick layer of tree bark, rough compost, shredded wood, or any of the other mulches available. By adding a layer of mulch to clay soil you not only can help keep the house clean, but can reduce the number of weed seeds that sprout (mulch will smother out weeds seeds that might try to germinate) and enhance the amount of moisture that your soil retains for better plant growth.  Mulch will slow down water run-off allowing clay soil more time to absorb, and store, the water.  A layer of mulch is also cooler than exposed soil so it helps to reduce temperatures overall in the garden.

In general having a clay soil can be wonderful, IF you know what the strengths and weaknesses of that clay soil are and how to garden best in this type of environment. You expend a bit more energy getting things planted and preparing garden beds, but in the long run you’ll use less water and fertilizer than folks gardening in sandy soils AND most plants prefer some clay in the soil to help them get their roots established and improve their hardiness.

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Anonymous's picture
Anonymous Thu, 07/28/2016 - 9:38pm

We just planted two Chinese Pestache trees in our backyard about 20 feet apart. The ground is solid red clay. One of the trees is doing great. It's water soaks into the ground quickly and is green and thriving. The other tree is not doing well. The water just stands and won't soak in. The leaves are dry and crunchy and are starting to fall off. Our local landscaper said to water it more but it has bookoos of water! PLEASE HELP!

Bec from Lubbock, TX

Kerry Meyer's picture
Kerry Meyer Wed, 08/10/2016 - 7:34am

Bec,

It sounds like your clay soil isn't really allowing the water to perclate into the soil. While disturbing the soil so shortly after planting isn't ideal I think that is what you are going to have to do.  Find some compost and work it carefully into the soil around that tree.  The compost will add air space and allow water to soak into the soil better. Organic matter added to the soil is really the only optioin to really improve clay soils.

Anonymous's picture
Anonymous Mon, 07/11/2016 - 11:30am

I live in Middle Tennessee and our yard is new construction stuff, which basically means it is rock and clay and requires a pick ax to dig a hole. I dug a hole and planted a Cherry tree back in March. The tree did fine, blossomed and was doing great until June. The leaves began to wilt and then turn brown. We thought the heat was drying out it so unfortunately we over-watered. My husband dug the tree up last weekend and the hole was full of water. It did not drain for a long while even with him poke at it with the shovel. It rained last night and the hole filled up again. I have a blue spruce I wanted to plant there but my husband said we could not plant anything there, like it is a Bermuda Triangle area! Is there anything we can do to condition the hole or dig deeper to a point where it will drain? Now I hate to not have anything growing there because it is smack in the middle of an ornamental garden area. All of the other plants seem to be doing fine. Thank you. Mary Jane

Anonymous's picture
Anonymous Mon, 08/01/2016 - 3:31pm

Hey Mary Jane,
To be honest, it doesn't sound like the soil you have available to you is all that well suited for anything. The clay and rock will present a lot of difficulty for plants and trees of nearly any kind to establish; but there's hope! Depending on what it is that you'd like to accomplish, trees will most likely grow fine there but not at a young age. I personally grow everything out of raised beds because it gives me the ability to control the soil as well as be creative during the building process.
You could build a bed in an area where you'd want your tree without a bottom and the walls would retain the soil of your choosing. Over time as your sapling grows, the roots will grow strong and healthy, eventually being able to pierce through the rocky-clay soil beneath. You could then choose to remove the walls and rake the soil out or leave them for decorative purposes.
Hope that this was helpful and good luck!
Joe

Anonymous's picture
Anonymous Mon, 05/23/2016 - 3:47pm

I live in Illinois and my soil isn't red, but I'm told it has a lot of clay in it. I planted zinnia's for the first time this year ....I'm watering twice a day as they start to get "wimpy" toward late afternoon. The soil looks hard and cracked. When I take a hand spade to it there is a "crust" on top and the dirt below is very dry. I think the water is just drying off the surface and not making it down to the root. The flowers have been in the ground about 3 weeks now. Should they already be established?? I've loosened the dirt around each plant two times now...but the dirt just hardens after I water. Also....dusty miller, which usually grow easily for me...aren't getting any bigger. I've fertilized one time. Any help???? Thank you.

Anonymous's picture
Anonymous Fri, 06/03/2016 - 9:32pm

My Zone 7 heavy clay is kind of rust colored, but I had a delivery of light brown topsoil a couple of years ago that had the unfortunate texture of (bleached?) clay. The part of my yard which has not been enriched with leaf mulch is exactly what you describe except that there are an enormous number of large and small rocks and fragments of rocks. Plants do need time to adjust to new surroundings, and rumor has it that more plants die from being drowned than anything else. Do you know if you have acidic or alkaline soil? -or which these plants prefer?

It sounds as though you have aerated the soil around the plants, but maybe you need to go deeper and wider? If nothing else, I recommend mulching the top of the soil around the plants and cut back on the watering. Pine bark is my preferred variety. I like to mix just a little mulch and/or perlite into the soil before I set the plants. Other people swear by vermiculite, instead. Whichever you choose, do make sure you tamp the soil down to eliminate air pockets where water can pool under the surface and contaminate the roots. I have successfully grown dusty miller (and all sorts of other plants and shrubs) using these methods, which is not to say I don't ever lose any. Happy gardening!

Anonymous's picture
Anonymous Tue, 05/31/2016 - 8:16pm

HI there!
OK so it sounds like you are getting a water seal on the surface of your clay soil, there's anot a lot you can do short of rototilling the area and adding a LOT of compost to help keep the clay from binding together so tightly it repels water, but the easiest thing you can do is this: Mulch

Apply a layer of shredded wood or some other wood mulch product. It should be at least 3-5" deep between plants and only 1/2" deep where the plant goes into the soil. This thick layer of mulch will help slow the loss of water from your soil (this is what forms that crust on top) it also gives you a slow moisture to help water penetrate deeper with each watering, and finally also helps control weeds that might seed into your flower beds.

On how long it takes to establish annuals, three weeks should be plenty of time if they are getting enough moisture.
Your fertilizer once in three weeks should also be fine - if the fertilizer was applied as a granular or slow release fertilizer under the mulch this would also help to retain that fertilizer and make it last longer.

I hope this helps and let us know if you have more questions. Another place to check for more information would be the Illinois Cooperative Extension office in your county. You can find your county office at this website.
http://web.extension.illinois.edu/state/findoffice.cfm

Best of luck and happy gardening!

Anonymous's picture
Anonymous Sat, 05/21/2016 - 9:32pm

This is the beginning of the second year I have lived in this home. Because we had a lot of rain this year in Indiana I have an erosion issue in the back of my home and I live on a slight incline. We have tried topsoil and it seems that washed away and I was wondering what are not clay soil would help mix with some mulch and organic soil. I need some suggestions ask you how the control the erosion. The soil underneath is hard and has lots of small rocks. I am able to grow grass and to use the weed and feed it's just this one small area that seems to be getting consistently worse over time. Do you have any suggestions for me? I would appreciate any advice. Thank you.

Anonymous's picture
Anonymous Tue, 05/31/2016 - 8:23pm

HI there -

OK so on this erosion problem, one of the best way to help control erosion is to use the mulch just as you thought. A lot depends on how much water is passing through the area during an average rain? If it is flooding through, mulch may not be enough and it might require either a stone retention wall or a planting of shrubs across the area to help hold the soil in. Think of it like this: IF erosion is not a stream of water moving through, then mulch (4-5" thick) is likely good enough to hold and slow that water so it doesn't eat away at the soil. IF the water moving through is like a temporary stream, then you need a more permanent solution, like the rock barrier or wall, planting shrubs is a long term solution and will not immediately solve the stream of water. In a few years those shrubs will hold the soil in place and also help soak up that water before it causes more problems.

I hope this helps and have a great week!

Kerry Meyer's picture
Kerry Meyer Tue, 05/24/2016 - 10:36am

Using clay soil really won't solve your problem.  You need to get plants established and growing - grass is great, but other platns will work as well.  When you plant the area with seed you'll want to cover it with one of the straw mats - they will help hold the soil in place while the plants get established.  Roots are the best, and really only way, to hold soil in place...

Anonymous's picture
Anonymous Fri, 04/22/2016 - 11:26am

I was surprised to learn that with clay soils you you end up watering less than with sand soils. With the changes in weather that I have I think this soil type will also help to extend my plants hardiness. When I'm doing the landscaping for my yard I will consider using clay soil.

Kerry Meyer's picture
Kerry Meyer Tue, 05/24/2016 - 10:33am

Clay soil certainly has some benefits.  The drawback is that clay soils can be slow to drain which causes it's own issues.  The best soil is a good loam.  So if you are going to purchase soil, look for a loamy soil which has the best of both worlds, good drainage, but with good capacity to hold water - basically the perfect middle ground.

Anonymous's picture
Anonymous Mon, 04/04/2016 - 10:20am

I live in Oklahoma, I have dug up my garden and now all I have are hard clumps. I have put in 3 bags of compost 3 bags of topsoil and it's still a rock hard clay Garden what to do?

Rick Schoellhorn's picture
Rick Schoellhorn Thu, 04/07/2016 - 8:13am

Hi there -

I am imagining you with clods of clay mixed in compost/ topsoil and scratching your head, I completely understand this kind of upgrading of your soil takes time. You'll need to add compost/top soil yearly and it may take as many as five years to really get a good garden built up. Remember 'top soil' is compost mixed with sand or local soil, so you'll get faster results if you add only compost (the extra ingredients don't help as quickly) sometimes your local utility service will give away shredded composted wood and that can be a less costly way to get enough compost quickly. It takes a LOT of compost to counteract clay soil, think in terms of wheelbarrow loads and not just bags, it may take up to 20 bags of topsoil to really help (depending on the area you are trying to amend.

Also see if you can find Gypsum at your local garden center, gypsum acts to keep clay soil from sticking together and helps mix it in with your compost so it mixes much more easily.

An even quicker route can be to just build a raised bed and then fill it with a high quality compost or top soil, so you don't even dig into your clay. Check 'building a raised garden bed' on line and see if that might work for you! Here is a good link for the basics: http://www.garden.org/howtos/index.php?q=show&id=1310

Also you might try contacting your local master gardening program and asking them for help. They are part of your county/state cooperative extension service and have a volunteer help line you can call with questions: http://www.hortla.okstate.edu/research-and-outreach/programs/OK-master-gardener/oklahoma-master-gardener-program

Don't give up - it is worth it!
Have a great week!

Anonymous's picture
Anonymous Tue, 03/22/2016 - 6:22pm

Hi I'm located in Richmond Va and we are in need of some assistance. We have what I would call a clay soil based on very thing I've read and we have been unable to successfully grow and maintain a lawn. Our front yard is approx 5000 sf and half is full sun and half is shade. For the last five years we have either rototilled or aerated the lawn, applied lime, fertilizer and seeded usually in March. Usually the grass starts to grow and then dies. Our most successful attempt took place when we rototilled the yard we had a good amount of grass grow however eventually it died, Funny thing is weeds and moss grow real well in the yard.
What are we doing wrong?

Rick Schoellhorn's picture
Rick Schoellhorn Thu, 04/07/2016 - 7:59am

This is a tough question because there are so many variables: the type of grass. the soil pH, the sun versus shade. I don't really think I can help much but you do have some options:
1. Contact your local county cooperative extension service, they can walk you through the steps to figuring this problem out and they are local so they provide information specific to your region. Here is the link, just go to your county and then look for information on home gardening. They will be able to help.
2. Contact a local landscape service or garden center and see if they can help.

Sorry but how to get a good lawn growing, isn't really anything we can help to much with, it is fairly specialized information. We want you to succeed - so I really recommend contacting your extension service.

Have a great week!

Anonymous's picture
Anonymous Sat, 03/05/2016 - 9:26am

I live in Denver & dirt here is clay need lot of water. One of my friend suggested to mix sand. Last year, I used Miracle grow garden soil & also garden dirt mix but it did not work. Any suggestion?
Thanks

Anonymous's picture
Anonymous Mon, 03/07/2016 - 3:06pm

Hi there -

OK so you are in Denver, I used to garden there, well there and Fort Collins so I know your soils pretty well. In order to counter dense clay soils you need a LOT of compost, if you just add sand it can also turn the clay into cement, so compost is easier and more likely to succeed. A regular potting soil is a bit too fine and it can disappear into a clay soil very quickly. Ideally you want something a bit like mulch, but more aged.

A1 organics is in Commerce City uses manure and wood products to make a compost that would likely work (http://www.a1organics.com/PDF/A1Brochure.pdf) but you may need to buy it by the truckload (call & check, they may even deliver), otherwise I would call and see what options you have at some of your local garden centers, there are some wonderful places in Denver area. Paulino's (http://www.paulinogardens.com) Echters (http://www.echters.com) or any of the other garden centers. They would be selling it by the bag is you have a smaller project.

Research has shown that for perennials and shrubs digging a hole twice as large as the root ball of the plant you are planting and mixing compost with the soil that came out of the hole is just as good for getting a strong garden as working the whole area you are planting with a rototiller. However all that depends on what you are planting, if it is a vegetable garden or a big flower bed of annuals and perennials, you might be better off with the rototiller.

I hope this helps and have a great spring!

Anonymous's picture
Anonymous Tue, 09/29/2015 - 9:28pm

So I love in Shasta Lake, California where we have red clay. I made raised garden beds, and bought bags upon bags of "vegetable garden soil." I can water a garden bed for several minutes or more...and when I turn the soil...it's wet about 1/2 inch on top, but still dead dry just below the surface. What can I do to get a better quality soil that will get wet all the way through? Its odd because I have to wonder where all the water just went! In a water crisis like we are having every drop is vital and valuable!

Rick Schoellhorn's picture
Rick Schoellhorn Wed, 09/30/2015 - 2:04pm

OK so it sounds like most of the water you are applying is running off instead of penetrating down into the soil. So there are a couple things to you can do that will really help.

1. Get a drip irrigation system installed where you are planting your plants. The big problem with clay soils is that when they dry they become 'hydrophobic' or afraid of water. The water just beads up and rolls away. By using a drip system you can apply water at very low rates over a longer period of time (1-2 hours) and the slow rate of watering helps the water penetrate down into the soil instead of running off.

2. You mentioned raised beds, the key to raised beds is make sure they are fairly water tight, or that the downhill side of the bed is lined in plastic, because you want to trap moisture within the bed. If the beds repeatedly dries out, or develops cracks where water just runs out and down without slowly penetrative, it can actually be worse than plants planted in the ground because they will dry out less than a leaky raised bed.

3. Mulch, mulch, and more mulch - so the thicker a coating of mulch you can put on top of the garden soil, the better it works to keep water from evaporating out of the soil. You don't want mulch to touch the plants in the bed, but it should be close to them so that all the moisture mulch holds in - is where the plants can reach it, nearby. Usually I leave a gap around each plant of a couple inches, then mulch at least 3" thick everywhere else..

4. The other problem with clay soils, is compaction, once they get compacted they become even more resistant to water penetration. The most common tool to break up compacted soil is a rototiller, but they can be bulky and expensive and hard to use in smaller garden areas.

One simple trick I have learned is to make reservoir holes through the garden and water them instead of sprinkling. Water in these holes slowly moves sideways and downward and if you have reservoirs around your flowers or vegetable garden these holes can actually work to slowly water nearby plants as water seeps out of the hole into the surrounding soil.

If you dig a hole (as though you were going to plant a shrub or tree) say 18" deep and wide. Take all the dirt you remove from the hole and set it aside, re-fill the hole with compost or finely ground pine bark, or whatever you use for mulch (BUT do not put dirt back in, only organic plant parts like lawn clippings, or bark, or leaves).
Then mix more mulch at least 50:50 with the soil you removed and use that mix to build a low berm around the hole you dug, make that berm 6-8" tall with very wide sides, so it looks like a small pond.

OK so now you have a hole filled with only organic matter surrounded by a small berm. Now fill this hole with water and fill it until it is just below the top of the berm. You don't want water flowing over the berm and eroding it. Over time the organic matter will breakdown and the hole may need to be refilled with fresh material every now and then, but in the mean time you leave a hose filling these mini-reservoirs and plants nearby will get good deep watering without a lot of water wasted.

I hope this helps and thanks for contacting Proven Winners!

Anonymous's picture
Anonymous Fri, 08/07/2015 - 6:20pm

My neighbors just cut down 2 trees that used to shade most of my front yard, which is a fairly steep hill ending in a 3-ft retaining wall. I want to use this opportunity of full sun to plant asparagus, blueberries, raspberries and some sun-loving flowers. Our soil is heavy, acidic clay, now growing weedy zoysia grass, azaleas, English ivy, and poison ivy. How do I amend the soil without it washing down the hill? Terracing is not an option because of our historic district zoning rules.

Rick Schoellhorn's picture
Rick Schoellhorn Wed, 08/12/2015 - 8:36am

OK - so in terms of working on this slope....
My guess is you are going to want to first control the existing plants either by trimming or by applying herbicide, but once that is done my suggestions is to either use a heavy (6" deep) layer of mulch (and mulch can sometimes be ordered free from your local utility company or a local tree service).
OR if you want to bring in rock and make rock paths across the slope to give your self easy access to the edible plants.

1. CLEAN UP - Get rid of weeds or competing plants before planting anything new.
2. ACCESS - Make it easy to get to the plants so harvesting is fun and not a slippery, dirty process.
3. COVER - Mulch heavily everywhere - the mulch will help in a lot of ways.
a) to keep weeds from emerging wherever there is bare soil
b) to keep mud and dirt from eroding
c) to keep moisture in the soil between rains and watering
4. BASINS - create a small basin or bowl around each plant when you plant as this will help to hold water and keep it near your desired plants rather than just running downhill. The basin should be at least 18" around and really just deep enough to help trap water and direct it to your new plants..
5. AMENDING THE SOIL - Experts go back and forth on how much amending is really necessary, we suggest you make the planting hole 2X the size of the new plant. Inside the hole mix your native clay with a good planting mix or potting soil/or compost. Use the excess clay from inside the hole to build that basin around the each plant. In between plants I would not worry about amending the soil.
I hope this helps and good luck on the new bed!

Anonymous's picture
Anonymous Tue, 08/04/2015 - 3:58am

Hi there
My plants aren't growing as well. Is there any nutrient I can or should add to help? I'm worried that my heavy clay soil is not letting the roots breath enough. Any advice would be welcome.

Rick Schoellhorn's picture
Rick Schoellhorn Wed, 08/12/2015 - 8:41am

Hi there!

OK if you are worried about plants being stunted in clay soil here's a couple thoughts:
1. How is the watering? Clay soils usually hold a lot of water but depending on where you are in the US they can be very dry as well. In clay soils the best way to help plants grow is to have consistent moisture, but not extremes of too much or too little. Most people find a drip irrigation systems in the simplest answer.
2. On nutrients etc. It is best to know what you have before adding new nutrients, but it can never hurt to apply some basic fertilizer (except in fall when plants are trying to get ready for winter and do not need a boost of energy). If you want to find out the nutrients in your soil try contacting your local cooperative extension service, they usually do free or very economical soil tests for homeowners. Once you know what you have (or don't have) then you can fix it!

I hope this helps! and let us know if you need more info!

Anonymous's picture
Anonymous Fri, 07/10/2015 - 5:54pm

we have a very large garden with soil that becomes rock hard making it very hard to till, weed, and even for the tiny seeds to break through the ground. Root crops do poorly.The top few inches has some sand in it and then we have clay. There is no workable topsoil to speak of. We need an economical way to add fibre to the soil so it will break up easier Our garden is very large so must be something cost effective. Thx

Anonymous's picture
Anonymous Mon, 07/13/2015 - 12:37pm

OK so for a garden location with little to no top soil, your goal is to build top soil. Best ways to do this are compost, manures, and wood chips/rice hulls/straw bales whatever is locally available. You can work all of this into your existing garden bed which is a lot of hand labor OR you can build raised beds and simply allow the mixtures to settle for a couple months and then start planting, replenishing the mix as it subsides over time. If you are using compost most likely the two have already been blended to speed decomposition and that is what makes compost (manure + raw wood or other organic cellulose = compost).

IF you are doing the mixing you want to mix about 1 part manure to 2 parts raw wood etc. The main thing you have to be careful of is the balance of manures to raw wood or rice hulls.The danger of too much manure is that it burns the roots right off plants if it is too hot (hot = too high in nitrogen). The danger of too much raw wood etc is not enough nitrogen and these raw mixes tend to suck the nitrogen right out of your plants, making them turn yellow with dark green veins, also called chlorosis. So a good compost or garden soil is a combination of both of these materials in balance with each other.

OK so here are some ideas on how to build up your garden quickly and easily, no matter which method you want to do:
1. Most garden centers can recommend you to local sources of compost, manure and wood chips, etc.
2. You can also look for local lumber mills as they often sell raw shredded wood products and mulches as well as compost.
3. Try any local dairy farms, chicken/egg producers, horse ranches, anything like this as they often have piles of manure looking for a home and may deliver or let you pick up.

Many folks begin in fall by layering manure and compost in their veggie gardens and letting it sit all winter to age, then in spring it is a simple turn of the soil and they have a great garden soil to plant in!!

Hope this helps!

Anonymous's picture
Anonymous Sat, 05/16/2015 - 12:21pm

Hi! I live in Kennesaw, GA and recently had some work done to my back yard - the crew removed a large tree and leveled the remaining yard. They used clay to backfill the tree hole and to level the remainder, so in some spots, there is 3 feet or so of this clay backfill. After they were done, they laid new sod and watered. That is when the fun happened - all of the areas that were extensively backfilled are permanently boggy now. If I step on any area, I sink 3 inches or so into the sticky mud. Most of the grass died within a week. I spent a small fortune on this project to have a usable backyard space, and now we can't even step one foot into the yard. The landscapers are coming this week to re-evaluate, but I need some advice on what the best way to remedy this situation is. Please help!

Rick Schoellhorn's picture
Rick Schoellhorn Tue, 06/02/2015 - 10:45am

Hi there - sorry for the delay in responding, hopefully the landscapers have resolved your problem?

IF not my suggestion would be to get a sandy topsoil and begin top dressing that part of the yard on a regular basis, essentially building up a blanket of better soil to cover the old clay fill, over time (weeks to months) it should begin to stabilize and the problem should go away. More radical approach would be to dig it up and start again with a better (sandier) topsoil as fill.

Best of luck!

Anonymous's picture
Anonymous Mon, 03/16/2015 - 7:52pm

My yard has a layer of clay over soil thanks to a landscaping guy that was an idiot as the yard has moisture toouch as it is. My yard is huge and don't want to have to pay again to remove. I want to plant a garden and garden and flower beds and read what u have on here. I also want to grow grass and do patio stones. What do u recommend to put on the clay for that. Thanks anything is helpful now as I am frustrated with the sloppy mess of an incompetent landscaper.

Rick Schoellhorn's picture
Rick Schoellhorn Tue, 03/17/2015 - 11:07am

Hello there -

OK so as part of a landscape install the landscaper applied a layer of clay over the top of your soil? It may turn out to be a good thing as clay has a lot of great properties for growing plants. Do you have any idea how deep that clay layer is? and if you can give me a rough idea of what kind of soil it is covering it would help too. Also if you can tell me where you live it will also help - just a nearby city, and state is all is need, Is this a new home or a renovated landscape? IF a new home sometimes all the surface soil is scraped off and it exposes the clay beneath, so it may be that clay is all that is left, IF a renovated landscape then you may likely know what the soil was like before the clay went over it.

If it is truly a layer (not a solid mass) of clay then the best thing to do is try to mix it with the underlying soil, using a rototiller of some kind, by blending the two soil types you may get a good mix and be fine. As you say the yard had too much moisture even before they did this, so you may be looking at a clay layer underneath the new layers in which case rototilling will not mix things up.

However if you have a heavy clay soil the best thing to do it is add organic matter, not a fine organic material like peat moss but a chunky bark or wood compost. This brings in and AND organic matter and allows roots of plants to begin making their way through the soil. Amending a heavy clay or compacted clay layer is not something that can be fixed instantly but over time tree, shrubs and flower roots will begin to lighten the soil up, so all is not lost.

Another option is to make berms of a good top soil in areas where you may do intensive planting (tees, shrubs, or flowers) this berm will act as your top soil and by the time roots get through the berm into the clay beneath the plants will already be well established. BUT be very careful you do not create dams as well a berms, make sure to allow for bulk water to move across and out of the yard and away from the house.

I hope this helps and let me know the answers to your questions above and we can talk more!

Here are some links that may give you some more information:
http://www.gardendesignexposed.com/heavy_clay_soils.html
http://www.garden.org/howtos/index.php?q=show&id=1310
http://homeguides.sfgate.com/drain-heavy-clay-yards-54529.html

Anonymous's picture
Anonymous Tue, 02/24/2015 - 5:29pm

Is clay the soil that comes beneath your top soil? I've been wondering what I should do to prepare my flower beds for this coming spring, and the debate is over what kind of soil I should get. I think maybe a good mixture will be best.
<a href='http://www.randlessandandgravel.net/Purdy-Topsoil-and-Gravel/' > http://www.randlessandandgravel.net/Purdy-Topsoil-and-Gravel/</a>

Anonymous's picture
Anonymous Sun, 10/12/2014 - 6:45pm

Resolving the issue of sandy soils where there is no clay is hinted at, but not addressed. Please help those who have wind blown sand from the beaches prehistoric lakes to garden with. Describe how to add clay to this soil. Thanks!

Anonymous's picture
Anonymous Thu, 08/28/2014 - 8:08pm

I have so many slugs that they just ate five beautiful impatiens plants after they were blooming prolifically. My soil has clay and rocks but I always make sure to work with the soil when I plant and mulch each spring so my plants usually do pretty well. Any suggestions?

Anonymous's picture
Anonymous Tue, 05/05/2015 - 9:12pm

I've always been told to use crushed egg shells under plants that attract slugs

Rick Schoellhorn's picture
Rick Schoellhorn Sat, 08/30/2014 - 6:21pm

Hi -
OK so there are many options for slug control both:
1. organic
http://www.organicgardening.com/learn-and-grow/slug-stoppers
2. and chemical
http://www.weekendgardener.net/how-to/snails-slugs.htm

While it is true slugs like clay soils better because they stay moist longer, there's no reason why you can control them, the key is continual application of whatever bait or control you decide to use.

I hope this helps, I know slugs an be very frustrating!
Have a great week!

Anonymous's picture
Anonymous Tue, 07/01/2014 - 4:41pm

I've had a garden, well a weed patch for the past 7 years(weed patch due to my job). Now I have time and am trying to do the best with the clay soil I have. I've added peat moss, leaves chopped fine, and bark mulch to try and get it loosened up. Real hard clay here in central PA. Finally am at a point where things are looking good.

I got a bunch of pepper plants from a local farmers market that are in need of fertilizer(they were free). Going to try some tomato stake fertilizer at half the rate after reading this article. Amazing that it shows that my thinking was opposite from what it should have been. Who'd of thought that clay holds nutrients instead of not allowing them to get in.

Guess that's why the Amish and Mennonites are settling here. They have great crops with only a bit of manure.

Anonymous's picture
Anonymous Tue, 06/17/2014 - 8:10am

I have these clumps and need to break them down to seed this area. When and how is the best way to accomplish this?? We want to seed this area to grass. about 20 feet wide by 150 feet long.

Anonymous's picture
Anonymous Sun, 05/04/2014 - 11:13am

Was hoping to find a list of annuals that hold up in clay soil. Helpful info about amending soil. I have been using the 'spot improvement' technique for many years and have not seen much improvement. Have resorted to actually hand removing the larger clay clumps and replacing with good topsoil. How can you have good loamy soil and clay soil scattered throughout your property? Have found amazing dirt in areas where I do not plant flowers.

Kelly Geoghegan's picture
Kelly Geoghegan Tue, 05/06/2014 - 5:43pm

Most plants don't do well in clay soil but here are a few who can!
Any of the Timeless™
Any of the Boldly™
Any of the Caliente®
Amethyst™ Coral Berry

Hope this helps! Kelly Geoghegan PW

Anonymous's picture
Anonymous Sun, 11/10/2013 - 7:30am

this information really helped me so much. thank you

Anonymous's picture
Anonymous Fri, 11/22/2013 - 11:33am

Was really helpful by answering a lot of questions I had.

Anonymous's picture
Anonymous Sun, 11/10/2013 - 7:27am

wow. i am really impressed. this information did help me so much for my project

Anonymous's picture
Anonymous Tue, 06/18/2013 - 3:34pm

I have been adding organic matter to my clay soil for the last 2 years and it defintiely helps...put its also a lot of hard work. I've added leaves, shredded newspaper, soil, and grass clippings. I've taken everything up 2x and am about to do it a 3rd time. This time I am going to add more soil and leaves in order to raise my flower beds. Once the plants are taken up, I will fill the holes and mix up the soil/clay/organic matter (adding a few inches) then put the plant back down at ground level and cover with the new soil/compost/leaves/organic matter mix. That should give about 2-3ft of good soil vs the 8-12 inches that I started out with. Some of my plants have a hard time developing good strong roots, therefore they grow very slowly if at all...while others have no problem with clay...hopefully this does the trick and I'll continue to add compost over the years to come.

Anonymous's picture
Anonymous Thu, 04/25/2013 - 8:41am

This information is very helpful. Thanks very much.

Anonymous's picture
Anonymous Sat, 04/14/2012 - 7:41pm

Thanks for the info, this will get me going in the right direction for my Garden.

Anonymous's picture
Anonymous Mon, 08/29/2011 - 10:04pm

I have had trouble with my flower garden for three months. Finally, this article gives me some hope and some solutions.

Anonymous's picture
Anonymous Tue, 02/28/2012 - 1:16pm

Amen !!! Thank you for the much needed info.

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