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The Dirt on Dirt - Potting Soil

How to choose a good potting soil.

Contributors: Rick Schoellhorn

What makes a good potting mix?

Almost any article on plants ends with "and make sure you use a good potting mix" - great advice, but what does it mean? Let’s go over some of the basics and see if we can answer that question. To know what a good potting mix is you kind of need to know what the purpose of a potting mix is, so let’s discuss that first. The main functions of a potting mix are:

  1. To hold moisture and nutrients around your plants roots, acting as a reservoir for these critical elements of life in your container garden.
  2. To provide enough air for growing roots to be able to breath and not rot once you plant your container. Most people don’t think about this, but it is critical to have a good amount of air in the soil.  Not enough and usually the plant roots have a hard time surviving.
  3. To support your plant, providing anchorage for the roots. A soil mix needs to settle around the roots of your plant and help hold it in place, so that it doesn’t blow over from the first wind.  However, it also needs to be light enough to allow water and air to always be present under the soil surface so your plant’s roots have a balanced atmosphere to grow in.

So given that a good potting mix does these things, any number of different materials can be used.  I know many gardeners use soil from their garden in their pots, some make their own compost and add this to their containers. You can do any of these things, but if you are making your own potting soil at home you will also need to change the way you water and fertilize in order to get the best results. From hydroponics to sewer sludge, there are a million ways to mix up a potting soil, however, the potting soil you buy at most garden centers is a simpler blend of some basic items.

Rules of Thumb For Choosing a Potting Soil:

  1. Potting soil used in containers should be light and fluffy.
  2. Look for a potting soil made up of peat moss, pine bark and perlite or vermiculite
  3. Fertilizer may be added in the form of a "starter charge" or slow release formulation.  Adjust your fertilization practices accordingly
  4. Potting soil may use moisture retaining treatments, watering patterns may need to be altered if you use a potting soil containing these substances.

What is in potting soil?

Most potting soil you buy in a garden center are comprised of three basic ingredients: peat moss, pine bark, and either perlite or vermiculite (to provide air space).

Peat moss comes from the peat bogs of the northern United States and Canada; this is usually considered the higher quality type of peat moss. There are some peat bogs in the southern US, but they generally are considered to be slightly lower quality. Peat moss provides a great moisture retaining quality with good air space for healthy growing roots. For acid loving plants, like azaleas or Hydrangeas, this is sometimes the very best potting mix, however, for most flowering annuals peat moss by itself is too acidic.  So it is usually best to go with a blended potting mix that has all three ingredients. You can use straight peat moss as your potting mix, but be careful not to overwater.  Peat moss all by itself can stay wet for a long time after watering.

NOTE: If you buy a bag of straight peat moss and it is very dry, you may find that it repels water.  If you run into this problem, the best thing you can do is soak the peat moss either in the bag you bought it in or in a wheelbarrow or bucket.  Usually soaking it overnight will get things well saturated and then it can be easier to use. Once it has been saturated, it will usually go back to retaining water with no further issues.

Pine Bark comes from paper mills all over the United States and Canada and acts to provide some moisture and fertilizer retention, and also a bit more air space. All by itself pine bark does not provide enough of anything to really support plant life (except for possibly orchids, see below under specialty mixes), but once it is mixed with peat moss - pine bark adds a new dimension and helps extend the ‘life’ of the potting mix by being relatively slow to break down.

Perlite & Vermiculite are both volcanic in origin and both are put into potting mix to provide additional air space and to lighten things up so a potting mix is not too dense and heavy. Perlite does not provide any nutritional benefit and can collect fluoride if water containing it.  That means that flouride concentrates after a while and can burn the leaf tips of some houseplants like Dracaena and spider plant (Chlorophytum). It is rarely a problem with any outdoor flowering plants, so don’t worry if it is in your potting soil unless you are growing these plants. Vermiculite is a bit different in that it holds a lot of moisture and can also hold onto fertilizer for a period of time - helping to keep nutrients around the roots of your plants instead of washing out the bottom of the pot. There are even soil mixes that recycle styrofoam to serve the same purpose as perlite and vermiculite, this is also fine, but eventually the styrofoam rises to the top of the pot and blows in the wind, which can be a bit annoying.

To summarize: Peat moss provides moisture and nutrient retention.  Pine bark provides anchorage, some nutrient and moisture retention and air space.  Perlite and vermiculite provide most of the air space in the soil.

Quality ≠ weight

A lot of consumers confuse heavy potting soil with good potting soil. In most cases when a bag of potting soil is very heavy there are two reasons for it; it is either water soaked or it contains a lot of sand. In either case it isn't a good thing. If a potting soil is soaked it can begin to break down in the bag - losing all its air space, becoming compacted and is at risk for carrying root rot diseases besides being nearly impossible to get into your car.  Adding sand to a potting mix is another issue.  Unless you are growing cacti, adding sand (which provides anchorage and some air space) is usually not a great idea. In general, sand is added to a potting mix simply because it is a cheap filler.  Sand was used instead of more expensive components like peat moss or pine bark. If you live someplace with very high winds, a little sand can help hold plants in place, but in general it is not needed.

Fungal growth on potting soil

Most prepared soils that are bagged and sold at garden centers and home supply stores have been prepared months in advance of the actual sale. Normally, these mixed soils are composed, sterilized or at least heat-treated to eliminate any diseases, weed seeds and other pathogens that could ultimately impact what you are going to pot and grow in the soil. When you break open the bag and use the mix, you are exposing that sterile soil to a huge assortment of native fungi spores that are ambient in your home and garden. The sterile soil is a perfect home for these fungi (or mildews) since there is no competition for the organic material that makes up the soil mix. These fungi grow fast, especially when given the ideal growing conditions (which seem to be identical to those conditions we want to grow our new spring plants in.) Under normal outdoor growing conditions the fungi are usually short lived. Drying the soil mix out, exposure to sunlight and simply being exposed to other competitive organisms, the mildews disappear through rapid attrition.

Most of the time, the appearance of these mildews that grow on the soil means absolutely nothing to the health of the plants you are about to plant; other than an indicator that perhaps the soil is too moist or has too much organic material in it. If you want to eliminate the mildew issue, open the bag a few days before you use it and spread it out on a sheet or cloth, expose it to the sunlight, and then re-bag or put it into a soil bin when it is dry. You can use the soil without worry either fresh out of the bag or "conditioned and dried".

What is the difference between garden soil, manure products and mulch?

It can be really confusing to go to a garden center and try to pick out potting mix when it is mixed in with so many other options. But to keep it simple, just buy potting mix for your containers (look for a bag that says Soilless Potting Mix); all the other bags are for use in the garden or landscape.

Garden soil is essentially potting soil with a lot of other heavier and cheaper additives like compost, sand, clay and an assortment of other things depending on the manufacturer. It ‘can’ be used as a potting mix, but you run the risk of it being mucky and pulling away from the sides of the pot when it dries out, in general garden soil is for enriching the garden.

Manure products are great for the outside garden since they are rich in nitrogen, but not so good for pots since all that nitrogen tends to burn up your flowers instead of fertilizing them. Without making this a chemistry lesson, manure products need to be diluted into your landscape at a rate of about one part manure to two parts landscape soil. Using a manure based soil amendment directly on the roots of landscape plants or flowers will usually cause all the roots to burn and actually delay the plant getting a good start in your garden. So use them with care!  Also most manure related products contain a LOT of sand, which makes them heavier - too dense for good use in containers.

Mulch  is usually a raw wood product (bark, wood chunks, shredded wood, etc.) it is meant to be used on the surface of the soil to help keep water from evaporating, so that garden and landscape plants stay moist longer with less water and fewer weeds. Since they are raw wood products, they don’t work well mixed into your flower pots.  Raw wood products suck up all the available nitrogen from the soil as they break down and this means your plants look starved and yellow-green because they can’t get enough food to grow. Keep mulch products on top of the soil in your garden and landscape where they are meant to be.  They are great for decreasing water loss and if applied thick enough add some protection from annual weeds.

Fertilizer starter charge vs. Slow release fertilizer

More and more you see bagged potting mix with highlighted improvements on the bag. One of the more common ways potting soil is enhanced is with either a starter charge of fertilizer in the mix or slow release fertilizer mixed into the soil. Both are great ideas and help make things easier for you as a gardener, but there are a couple things you should know.

A “starter charge” of fertilizer means there is a minimal amount of fertilizer in the potting mix, but it is minimal and does not mean you don’t ever need to fertilize.  It just means you don’t need to fertilize right away.  Most starter charges are gone from the potting soil after watering two to three times. A starter charge can help you a little at planting, but you still need to regularly fertilize as well.

A slow release fertilizer in the bag means you have more fertilizer incorporated to help your plants transition into their new home, but it rarely lasts beyond the first month.  So again, you need to make sure you are regularly fertilizing in addition to the fertilizer in the bag.  One problem that we have seen with this slow release fertilizer is that if the bags of potting mix sit around for a long time or get wet and sit around, the fertilizer in the potting mix releases inside the bag and then when you plant your flowers they burn up due to too much nitrogen (similar to the problems with using manure products). So if you are buying potting mix with fertilizer added to it, check to make sure the bags are not wet and that the potting mix doesn’t look like it has been sitting around a really long time.

Moisture retaining treatments:

Like the fertilizer add-ins, a lot of potting mix is beginning to come with moisture retaining gels and chemicals added as well. Again, this can be a help in reducing watering over the course of the season and there really is no down side to it. You will need to exercise a little extra care not to overwater your flowers when the temperatures are still cool since the soil will not dry out as quickly as you are used to.  You also need to realize that most of these ‘moisture retainers’ will not allow you to leave for three weeks and have everything stay looking good.  The moisture holding ability of the soil breaks down over the season and by mid to late summer it is likely not doing much anymore.  So when you most need water holding ability - when it is really hot - it may no longer be working. 

NOTE: Just because the potting mix is moist doesn’t mean the plant won’t need fertilizer, a lot of gardeners live where there is enough rain to keep the potting soil moist, however, you still need to make sure that the plant has regular fertilization to grow well. A plant can starve to death in a moist potting soil, especially if there is a lot of rain washing nutrients out of the soil.

Specialty potting soils:

While the basic peat moss, pine bark and perlite type potting mixes will work fine for almost all annual flowers and mixed containers, there are some crops for which specialty mixes might be helpful. The most common is potting mix for orchids.

1.   Orchids require excellent drainage and most general potting soils are too heavy and hold too much water, so if you want to have healthy orchids you may want to purchase a specialty potting mix.

2.   Also succulents and cacti, require better drainage than annual flowers and in many cases prefer clay pots as well. Many succulent collectors use a regular potting mix and mix it with 50% sand, it makes the mix very heavy, but very fast draining.

Mixing potting soils

Like all aspects of gardening people succeed doing a lot of things differently and some gardeners really swear by mixing their own potting soils using everything from lawn clippings to fish heads to powdered clay.  As long as you adjust your watering and fertilizing to match your mix, plants are pretty forgiving and in some cases do even better with custom mixes, so feel free to experiment. However, there is one last thing that I think happens often enough that it might be worth noting here.

Have you ever run out of one potting soil in the middle of planting and had to switch to another type of potting soil half way through a large container? I know I have.  If you find yourself in this situation, I have a tip for you.  Make sure to blend the two types of potting soil as much as possible. By mixing them together you get an even blend of potting soil and your plants will do better. If you just pour a totally different potting mix on top of a different one and don’t mix them there is the possibility that if the two mixes are different enough your plants will have a hard time growing down through one mix and into the other.  There are a lot of reasons for this and rather than making this into a physics lesson, just take my word for it - blend potting soils if you find yourself having to switch in the middle of a container.  Your plants will thank you.

566 Readers Rated This: 12345 (3.4)
abuduri's picture
abuduri Mon, 05/20/2019 - 6:18pm

I just ordered calibrachoas to plant in my patio. I have container to plant them.. I would like to know if i can re-use my old potting mix or should i throw this out and start afresh. The containers have been empty for 8 months. The plants in them died while I was on extended office trip.

Anonymous's picture
Anonymous Fri, 06/01/2018 - 4:59pm

Accidently reported flowers in commercial bagged Top Soil. Do I need to repot them again in potting soil? Or can I just work in some potting soil around the plants?

Anonymous's picture
Anonymous Thu, 05/24/2018 - 7:48am

I had two raised beds built for my daughter to plant flowers. We are out of money and the only soil I have available is in a large garden area full of over grown weeds. What ould be the best option for soil to fill her beds?

Anonymous's picture
Anonymous Sat, 03/02/2019 - 10:16am

Dig up the soil, shake out the weeds. Add coffee grounds, chopped up seaweed-if you live near the ocean-or grass clippings. Go to the local dump; they may give away compost made from leaves. And start your own compost bin if you haven’t already so you can fortify the beds later on. That’s all I can think of...shouldn’t cost anything more than time & elbow grease. You can make a game out of seeing what you can repurpose to spend as little as possible. Try watching “home grown veg” on YouTube.

Anonymous's picture
Anonymous Fri, 05/04/2018 - 9:27am

Great article, you really know your onions! Do you think it is necessary to change the soil in containers every year, or could I just add fertilizer? Would save me a ton of work and money. Thank you very much for your help with this. Pauline

Anonymous's picture
Anonymous Mon, 04/09/2018 - 10:19pm

I have built raised beds. I have had many people tell me many different ways to build soil. I will be using the garden for fruit and vegetables. I will need approximately 4 yards of soil. Will 40% compost (manure and wood) 40% peat moss/ coco coir and 20% vermiculite be good soil?

Anonymous's picture
Anonymous Tue, 03/13/2018 - 12:11pm

Thanks for your article! I was wondering if you had any thoughts on growing water-loving plants in only vermiculite and then supplying a low dose fertiliser.

Thank you!

Rick Schoellhorn's picture
Rick Schoellhorn Thu, 03/15/2018 - 11:05am

Hi there- What you are describing is essentially hydroponics, where you are growing in a liquid fertilizer solution, using vermiculite to act as a soil. Some plants do very well in this kind of system, but it requires more attention to detail than growing in a potting mix, and it definitely requires a very complete fertilizer since there is no other source of nutrients.
It can be done but it generally considered to be a higher maintenance way to grow flowers.
I hope this helps! Have a good week!

Anonymous's picture
Anonymous Mon, 01/15/2018 - 4:41pm

I just planted my yard it was a big sand box. Just bought house never landscaped.Plants are not doing well. Watering 3 times a week. Should we do more. Read sand does not retain water well. Live in Az very hot in the summer. Leaves a turning yellow and some dried up.

Rick Schoellhorn's picture
Rick Schoellhorn Mon, 01/22/2018 - 2:14pm

Hi there -
OK so you have sandy soil in Arizona and want to make it more hospitable to plants. OK so there is no easy fix, but here are the major ideas:
1. Adds lots of organic matter to every hole you dig for a plant. Organic matter means composted wood products or whatever is available, peat moss is also common but fairly expensive to use on a large scale. Often your city or county may offer mulch (composted landscape trimmings for municipal clean up) for a lower price and as along as it is composted, that should be fine.
2. Look into drip irrigation, most gardeners I know of in Arizona have some sort of automated/timer driven drip irrigation system because that simply works out to be the most successful. It uses less water and only apply the water right to the plants you want it on.
3. Mulching with wood chips or pine bark can also help as a mulch around each plant helps retain water so that you need to water less frequently. Again you can buy this in bags or look for bulk orders from local landscape supply and garden centers as well.
There is no way around the fact that Arizona has dry soils, so keep your expectations of what will grow there realistic and try to select for plants that have a low water need to begin with. I would really recommend checking in with your county's master gardener office to see if they can also help you as they are staffed with knowledgeable folks who have gardened in your area for years. Try Googling the County you live in and master gardener, that should get you in contact with them.
Arizona gardening is unique to the US, you have incredibly high temperatures and incredibly intense sunlight, it means even the toughest plants will struggle in many situations. That's why talking to local experts is your best bet on plant selection and sources of mulch, or organic matter for planting!
I hope this helps and have a great week!

lizabethj2's picture
lizabethj2 Thu, 05/04/2017 - 12:59pm

1. After reading your excellent article, I think what I'm looking for is a basic potting mix without vermiculite rather than perlite and no added fertilizer. I'm nervous about over feeding the maidenhair because they can burn so easily. Could you please recommend a few potting soils by brand name that would fit the mix described above?
2. My maidenhair fern is in the pot I bought it in and I've noticed that the dirt in the pot is not filled up on the sides. Is there a reason it was potted this way? My instinct is to put a light potting soil in there because I'm worried that the plant doesn't have enough support, but it seems to be doing GREAT. It has lots of new fronds coming out. Should I add the potting soil or leave it alone? I bought the plant at Home Depot and I don't know what type of soil it's potted in.
3. I've also read that I should put some worm castings on top of the soil and then put mulch on top. Any particular brand of worm castings? Any particular brand or type of mulch?

Anonymous's picture
Anonymous Fri, 04/14/2017 - 6:05am

Hi, I really appreciate all the information you've provided in your articles. I am new to gardening and want to try container gardening. I bought two self watering containers at Lowes and four bags of miracle grow raised bed soil. Do I need to add anything to this soil to grow tomatoes, zucchini, and herbs? My husband is questioning all the chemicals and processing from any soil bought in a bag and thinks we should have soil delivered by the truck full. To me, that involves a lot of back breaking work and I would need to mix peat moss and vermiculite and other things. I am 60 years young but have arthritis in my hand and back and it just seems easier to open up bags and pour into the container and transplant plants grown from seeds. Your thoughts on Miracle Gro raised bed soil?

Rick Schoellhorn's picture
Rick Schoellhorn Fri, 04/14/2017 - 7:08pm

OK - there is nothing wrong with Miracle Gro soil and the raised bed type soil is likely a mix of garden soil with peat moss and bark, so it is simple and easy to use. Unless you are planting an area so large that truckloads of soil are required I would just take the easy option and relax. There are usually not a lot of chemicals in any potting soil, except maybe some fertilizer.

I'm with you, save the hard labor for emergencies and for this job take it easy on yourself!

Anonymous's picture
Anonymous Tue, 04/11/2017 - 3:59pm

Hi, your article is so helpful and I truly appreciate it!

Q: How can I amend or fertilize my iris/ perennial garden which is crowded and covered with mulch?

I know I need to separate my irises; I know, I know. But before I do that this fall, I'd like to enhance their soil, feed them as needed, etc. I've read that you're supposed to scratch bone meal in around the plants but that's 2 inches deep--and sounds like a lot of work! I'm physically impaired and have little stamina.

And how often to fertilize?

Fertilize with a surface product (which?) Or with water spray?

If necessary, I can pay a fellow to help.

Anonymous's picture
Anonymous Tue, 09/19/2017 - 9:31pm

You can buy bone meal already ground up at your local hardware store and also the big box stores like Home Depot, Lowes and probably Walmart. No need to grind it yourself.

Sarah Geoghegan's picture
Sarah Geoghegan Tue, 04/11/2017 - 6:34pm

Hi there!
It sounds like the best course of action would be to divide them this fall and then in the spring fertilize them when they start to grow. As for the fertilizer, I'll direct you to another page on our site which can go more in depth about fertilizing your plants. Best of luck!

Anonymous's picture
Anonymous Mon, 03/13/2017 - 6:28am

If I am using the miracle-gro potting mix that feeds up to 3 months, and I have plants that are 6 monthers, will I have to change the soil in 3 months or Would they be fine to live the rest of there lives for another 3 months in the first batch of soil?

Kerry Meyer's picture
Kerry Meyer Wed, 03/15/2017 - 1:49pm

They can stay in the same pot, no problem, the 3 months on the potting soil is for the fertilizer charge.  So the potting soil is fine, you just need to fertilize again.  You can get a controlled/slow release fertilizer and top-dress with it on the top of the soil.  Top dress just means you don't incorporate the fertilizer into the soil.  So go ahead and add more fertilizer and the plants should be good to go.


Kerry Meyer, Proven Winners

Anonymous's picture
Anonymous Sat, 03/04/2017 - 7:02pm

I have a pitcher plant that grows small water pitcher like objects at the very tip of the leaves. The pitchers also need water in them along with knat size incets. I keep it indoors in cooler/cold weather, outdoors (indirect sun) when its summer and hot. What is the best fertilizer to repot my pitcher plant and when?
Thanks in advance!

Anonymous's picture
Anonymous Mon, 03/06/2017 - 12:58pm

HI there!
OK your pitcher plant (Nepenthes) is a tropical plant, that means you want to wait until it starts to warm up before giving it any fertilizer or repotting. The best thing to do would be move it outside and let it adjust to the outdoor world and then, repot it and begin fertilizing.

For fertilizer almost any basic plant fertilizer will do, but try something that you can dissolve in water, then all you need to do is water the plant and apply the fertilizer at the same time. Nepenthes do not need tons of fertilizer to do well, they actually prefer about half strength, but applied with every watering once the temperatures have warmed enough to start growing again. You can also use fish emulsion or any of the natural/organic fertilizers if you like those, in which case use them at full strength since they are not as concentrated as manufactured fertilizers.

I hope this helps and happy gardening!

Anonymous's picture
Anonymous Sun, 02/26/2017 - 5:14pm

I've used "potting soil" for my houseplants for years, no, DECADES! I usually buy Hyponex Potting Soil. It always looked like plain old dirt with vermiculite added. I noticed about 10 years ago when I bought a new bag of Hyponex, and all the bags of other brands of potting soil I've purchased in the last decade all now don't look like dirt with vermiculite any longer. Now the material looks like ground up tree bark and peat moss and is no longer dense and's brown, "light and fluffy" as you described. The old Hyponex worked just fine on my plants. Has the industry made some "upgrade" it didn't announce? Did it run out of good plain dirt and start to go "green" by using debris from the logging industry? Or did I just not get "the memo"...?

Rick Schoellhorn's picture
Rick Schoellhorn Mon, 01/22/2018 - 2:23pm

Hi there -
OK so I think you are both on to something, but it can be dealt with. Potting soil suppliers have had to change ingredients over time as the world changed around them. The Hyponex soil and others of that type relied heavily on the dairy and beef industry for cow manure, so the old mixes were nearly black and VERY heavy. Since we now live in an age where everything moves cross country by semi most potting soils are made of lighter weight products, unless they are locally manufactured. For those of us who live in colder climates, the lighter mixes work fine, but for you in Arizona they dry out too fast in the blast furnace of your climate.
What I recommend is this, try finding either Black Cow or another bagged mix that feels very heavy in the bag (usually the weight is either the bag holding water, or that the mix contains a of of sand). Mix that potting soil, or it is sometimes sold as gardening soil half and half with the newer lighter weight mixes, it should give you the best of both worlds. You can also buy cow manure to give you the nitrogen kick that the older mixes has. Remember it is the manure that gave most of them their blackish color.
Another thing for Arizona in particular, is to use larger pots so they do not dry out as frequently. Luckily in AZ you have a great pottery market that has lots of color and textures to choose from. The glazed pottery holds water very well, while raw ceramic pots tend to dry out much too quickly. So check into that as well and avoid dark colors as they heat up in the sun and that can also be a problem. You can also check with your county master gardeners for localized info and suggestions on what to use and where to buy it.
I hope this helps and have a great week!

Anonymous's picture
Anonymous Thu, 01/18/2018 - 10:36am

I agree and also want information. I ended up on this site to try to "fix" the potting mixes to make them more like the old one's from the 1980s that I got at K Mart and that worked great with no issues. I don't get good root development now, and the mix just falls off the roots when I go to transplant even when I'm getting good products from reputable nurseries.The potting soil used to be nice black soil and work great. It looked like the lovely native soil we had in Illinois. Now I am in Albuquerque NM and just can't get it right with the available mixes and advice. I suspect that like everything else (eg less cotton and wool in clothing) the demand may have outstripped the supply with population increase and increase in consumerism. Speculation. If anyone knows what mixes well with potting "mix" to greate better root structure it would be a wonderful contribution to this site.

Anonymous's picture
Anonymous Fri, 11/18/2016 - 5:21pm

Hi. I live in Georgia and want to transplant some Lenten Roses before it gets too cold. Is it best to use potting soil or garden soil?
Thank you!

Anonymous's picture
Anonymous Mon, 11/21/2016 - 1:47pm

OK so when you say transplant will they be in pots or in the ground?
If in pots - potting soil is best, garden soil is usually less desirable for containers.
If going into the ground amend your garden soil about 50% with either a potting mix or a good compost, this will give the Hellebores a good rooting environment.
Happy Gardening!

Anonymous's picture
Anonymous Wed, 10/12/2016 - 9:07am

Okay I'm a first-time grower and I was wondering if I mixed topsoil to stretch my potting soil will that affect my plants I also bought some perlite to mix in as well

Anonymous's picture
Anonymous Sat, 10/22/2016 - 8:39am

Hi there -
OK so mixing top soil with potting can be a way to stretch things out and in general there is really no problem doing so, the perlite can also help is your soil tends to hold too much water, but for most folks keeping water in the soil is the hardest part, so don't use too much perlite unless you have problems with overwatering!

The only drawbacks to adding native soil to potting mix can be the inclusion of either diseases or insects that harm plants, in most cases you won't ever see a problem, but just be careful and use good garden soil if you are going to mix the two!

Anonymous's picture
Anonymous Tue, 09/06/2016 - 1:01pm

I found this piece well researched and well written. Will bookmark for our next round of spring gardening.

I have a question about turmeric powder - frequently used in food as an inti inflammatory agent and externally as a disinfectant. Can I mix turmeric powder in my potting or garden soil?

Thank you!

Rick Schoellhorn's picture
Rick Schoellhorn Mon, 09/12/2016 - 10:13am

Hi there -
I think all that Turmeric would do in a potting soil is quickly decompose, though there might be a short amount of time it helped with some insect or disease control, but it would be a very quick thing. My guess is it is not worth the trouble, unless you want to get rid of an older container of turmeric.
I hope this helps and thanks!

Anonymous's picture
Anonymous Thu, 08/11/2016 - 12:53pm

What would be the best potting mix (soil) for concrete containers which are on our condominium pool deck. We will be planting shrubs, not flowers but they will receive full sun in the middle south.

Stacey Hirvela's picture
Stacey Hirvela Mon, 08/29/2016 - 11:35am

Any standard potting mix will be fine - just be sure to pick select a soilless mix for container growing. Avoid top soil, garden soil, and products labeled like that. Learn more in our containers in shrubs guide:

Anonymous's picture
Anonymous Sat, 07/16/2016 - 8:02pm

Thank you in advance for your help! I am getting ready to plant new plants in a now plant-empty planter. Would you recommend mixing topsoil at a 50/50 ratio with my current soil? Or should regular potting soil instead of topsoil be mixed with the current soil? The current soil seems to be in pretty good shape and a landscaper recommended "Install one yard of high quality "50/50" planter mix topsoil in raised planter" as the appropriate solution. I am now trying to DIY it, and don't know what this means!!! Thank you!!

Rick Schoellhorn's picture
Rick Schoellhorn Wed, 07/20/2016 - 11:14am

Hi there!
OK so yes, I would recommend adding some fresh soil to this planter and a 50:50 mix (new soil added and mixed with existing soil, would be fine. Over years of planting a soil can become exhausted, so this is a great way to revitalize the planter.

Regular potting soil would also work but is usually a bit more expensive than a bagged planting mix. Also planting mixes tend to be heavier than potting soil and hold more moisture.

I hope this helps and happy gardening!

Anonymous's picture
Anonymous Thu, 07/07/2016 - 7:46pm

Is mixing blue corn meal and chile powder with soil a good idea? I have a ton of expired powder.

Rick Schoellhorn's picture
Rick Schoellhorn Wed, 07/20/2016 - 11:17am

Hi there -
OK so adding chili powder can be just like adding any compost, so I don't see a problem there. The corn meal however if it is mixed in in large amounts can bind water and nitrogen, so it would be best to only mix it in in small amounts and fertilize afterwards to help it break down.

Also if this is getting mixed into a garden soil, there should be no problems, but if you are mixing it into a potting mix I would be more careful, as too much of any raw organic matter can cause a potting mix in a pot to become, well kind of rotten, for potting you want to make sure that the powders have broken down and turned a dark brown before planting in containers.

I hope this helps and happy gardening!

Anonymous's picture
Anonymous Thu, 07/07/2016 - 5:37pm

I have a agriculture project I planted the same flower in thre different types of soil organic,peat moss and outside dirt they all look the same after 4weeks what would be the best one to use to get the best results

Rick Schoellhorn's picture
Rick Schoellhorn Wed, 07/20/2016 - 11:20am

HI there -
It seems like between your three mixes all are working pretty well, so it likely doesn't make a lot of difference which one you choose to use. Also it makes a difference what you are using the plants for, if they are going into the garden I think any of the mixes is fine, if they are going into containers, I would use the soil organic mix as it is closest to a potting soil (I imagine).

I hope this helps and happy gardening!

Anonymous's picture
Anonymous Mon, 06/06/2016 - 7:20pm

I have an issue keeping plants alive. I have replaced my bird of paradise after 3 years. I purchased a new one and repotted in a very large pot using mg potting mix. It doesn't seem to drain well. Could I gave packed too tightly? Any suggestions? Please help.

Anonymous's picture
Anonymous Thu, 06/09/2016 - 7:32am

Thank you for your question.
Usually the rule of thumb when re-potting plants, is that you only go to the next size up container so that the plant doesn't suffer from over-watering. The majority of the new container, if it is too large holds water that the small root system doesn't need yet..
You may want to evaluate the size container you have used and possible re-pot it if necessary. Your potting soild should be a type that is well draining as well.
You may want to check with your local garden center to find the best soil for the Bird of Paradise. It should include bark, peat moss and perlite or vermiculite.
I hope this advise is helpful.
Happy Planting!

Barb Balgoyen
Walters Gardens, Inc.

Anonymous's picture
Anonymous Fri, 06/03/2016 - 1:52am

Would I use the same potting mix for flowering plants? I'm purchasing roses, gardenias and Hibiscus

Kerry Meyer's picture
Kerry Meyer Mon, 06/06/2016 - 11:51am

Yes, the same potting soil htat you use for annuals will work for shrubs.


Anonymous's picture
Anonymous Sat, 01/30/2016 - 11:48pm

I need to force about 2000 tulips for a wedding in early april. I have refrigerated them for the past 6 weeks and need some advice on how to pot them and get them to bloom the first week of April. Can you help me?

Anonymous's picture
Anonymous Sun, 01/03/2016 - 2:45pm

I have a science project and my question is how does the type of dirt affects the growth of a plant?

Rick Schoellhorn's picture
Rick Schoellhorn Tue, 01/05/2016 - 11:46am

Hi There!
OK so the way soil affects the growth of plants is by either supplying or not supplying enough water or enough air (You can also add whether or not the soil provides nutrients to this list). All plants have different kinds of roots, so to a certain extent you need to match the soil to the roots of the plants.

Luckily most plants are pretty tolerant of a wide variety of soils. You have to think of the soil as being like a sponge you might use in the kitchen. It has solid structure, but it also has air holes in it. Just like that sponge a soil must have solid structure, big holes (or pores) and small holes (smaller pores). The big pores hold air once the water passes through after you water a plant, and the smaller pores hold water until even they dry out and fill with air.

The biggest issues gardeners usually have is a soil mix that stays too wet (and sometimes that is the because of overwatering) - a soil that stays too wet is usually a fine textured, very heavy soil. So it has very few pore spaces for air holding and everything ends up holding water. A plant trying to grow in it cannot get enough air for the roots to breathe because there is too much water held in the soil. Most plants rot under these conditions, their roots die and the the stems follow shortly after.

Does that help?
Happy Gardening!

Anonymous's picture
Anonymous Thu, 12/10/2015 - 2:21pm

I know all the articles say replant in the spring. But I need to move my ponytail palms and other houseplants inside. I live in Florida and we are still having days in the 70s. But tired of covering them when it gets cold so im making a room just for all my outdoor plants. And don't want to bring the critters in with my plants. Is it going to hurt them to repot. One plant is 20 years old. Thank you.

Rick Schoellhorn's picture
Rick Schoellhorn Fri, 12/11/2015 - 4:17pm

Hi there -
Chances are you will not have any problems at all, the reason they say to wait is that most plants will go into a type of dormancy indoors (the light is very low, they tend to be drier overall, and conditions are less than ideal) so if they are going to 'sleep' why pot them up? Garden wisdom says to wait until spring when active growth resumes and new roots quickly fill in the new potting soil.

But all things considered it will not make a lot of difference for most plants, just watch your watering so you don't over water by mistake and everything should be fine! Just be cautious about too much water and I think you will not have any problems!

Good luck! and have a great holiday season!

Anonymous's picture
Anonymous Mon, 08/31/2015 - 2:05pm

Could you tell me a good potting medium for planting a hydrangea in pots

Stacey Hirvela's picture
Stacey Hirvela Fri, 09/11/2015 - 2:05pm

You can use any regular potting soil that you find at your local garden center. If you find one that is a bit heavier on the bark (potting soils usually list their ingredients somewhere on the bag), that would make it an especially good choice, but really, any fresh, well-drained potting mix will do.

Anonymous's picture
Anonymous Mon, 07/20/2015 - 6:23pm

I've been a horticulture hobbyist on and off for a little more than a decade, and was brought here because this year I've been getting away from brand name potting soils and more into mixing my own. Today was the first day I'd run into water-repelling peat moss, and this came up first on google.

So I got my answer on *that*, but let me give my $0.02 on some of the other questions I see arising in the comments:

I know that a lot of people shy away from brand names, and tend toward "organic" potting soil very quickly - but I have two things to say about that.
1) The word "organic" is not very delicately legislated. There are SOME laws concerning its use, but not enough for it to actually mean anything. Unless you're personally familiar with the production of your soil, just assume the word "organic" doesn't mean anything.
2) I'm making my own soil because I find it an interesting addition to my hobby, but for many years I've used bagged mixes. After many experiments with different soils, back when I began my hobby, I found Miracle Gro Moisture Control Potting Mix to be tops. If you're not gung ho about making your own soil, I highly suggest giving it a try - it works as advertised. Even works with hefty plants that require a little more packing; you can shove down on it pretty hard and still have no worries about drainage.

There really isn't an amount of expertise that allows one soil to be better than another, it's about the soil. You won't graduate to a knowledge level where the soil you used as a beginner now yields worse results than the bagged soil "for experts." If you don't make your own, and you don't want to mess around with mixing types for tweaked, desired effects, then the same soil that's right for a beginner is right for a veteran. (Basically - don't overthink it and end up ego-ing yourself out of using the "soil for beginners".)

Anonymous's picture
Anonymous Thu, 07/16/2015 - 10:41am

I have my spider plant in a mix with top soil but it doesn't seem to be draining quickly. I want to switch out the soil but am not sure what I should get. I know the plants can be picky with soil. I was going to purchase a regular miracle grow potting soil but they all have some kind of feed in them, that is supposed to feed the plant from 3-6 months. Would this be ok? What would you recommend?

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