- 1 What's In Potting Soil?
- 2 What Makes a Good Potting Soil?
- 3 The Best Potting Soils
If you're growing in containers, chances are good you're using some kind of potting soil for your precious plants.
But what if I told you that the "soil" in your pot isn't technically "soil" at all? What if I told you that it's a mix made of composted tree materials, peat moss, and a myriad of other ingredients?
Well, it's true. Potting soil is a man-made creation that is in some ways superior to normal garden soil when it comes to growing plants in containers or pots.
In this article, you'll learn exactly what potting soil is, what makes good potting soil, and some of the best brands and recommendations for different types of plants.
What's In Potting Soil?
Standard potting soil is generally comprised of three things:
- Composted tree bark
- Sphagnum peat moss
- Vermiculite or perlite
While there can be many more ingredients, these are the base three that make up the bulk of most potting mixes.
These three ingredients are meant to hold nutrients and moisture while still giving your plants plenty of air.
What Makes a Good Potting Soil?
The simplest definition of good potting soil is this:
The best potting soil is one that offers the perfect amount of stability, nutrients, moisture, and air.
Let's go over each of these, one by one.
Quality potting soil will contain all of the nutrients that your plants need to thrive. They will include humus, finished compost, and / or gypsum and other ingredients to ensure optimal nutrition.
High quality potting soil will be light, fluffy, and not compact easily. It will allow the roots to access air and oxygen so they can develop optimally.
While aeration is important, the best potting soils must balance aeration with water retention. They need to drain well to avoid mold or rot, but hold on to some moisture so your plant's roots can drink.
Good potting soil will have a consistency that makes it easy for plants to anchor their roots. It provides stability for a plant's root system, preventing them from falling over or being torn out by the wind.
Weight vs. Quality
It's important to understand that the quality of your potting soil is not directly related to its weight.
It's easy to mistakenly assume that the heavier your potting soil is, the better it will be for your garden. In actuality, potting soil only ever becomes heavy due to two reasons: it is very wet, or it has lots of sand in it. Some companies also add in normal dirt or sedge peat, weighing the mix down.
None of these things are good, and it is best to avoid them.
Mold or Fungal Growth
Potting soils available for sale at garden centers are almost always sterilized and treated, meaning they should be free of mold or fungal issues. But once you open up the bag, you're exposing it to mold, fungus, and mildew.
Generally speaking, light mildew, fungi, and mold are not big issues. They usually will be dried up by the sun without ever causing any harm to your plants, and they are simply a sign that your soil might be too moist.
If you do want to prevent them from growing, though, simply spread out your potting soil on a sheet and let it dry in the sun for a few days before use.
Fertilizer Types: Slow Release vs. Starter
When you look at all the different types of potting soil available, you will most likely notice that many of them will mention fertilizer and use phrases such as “starter charge” and “slow release."
If a potting soil says that it has a “starter charge” of fertilizer, this simply means that it contains enough fertilizer to last your plant through the first few times it is watered. You will still most likely need to add your own fertilizer to the soil, but the starter charge at least helps your plants to get through the initial stages of their growth.
If a potting soil says that it has “slow release" fertilizer, this means that it contains slightly more fertilizer, but only enough for approximately a month.
Again, you will have to eventually add your own fertilizer, but slow release will last for at least a few weeks.
In addition to fertilizer, many potting soils will also contain added chemicals or ingredients that are meant to help retain moisture. This is a great feature, and it allows you to water your plants a little less often than normal.
You still will need to keep an eye on everything and make sure that you do not leave your garden for too long, but it does give you some breathing space.
An important thing to keep in mind with potting soil that has water retaining features is that you must avoid overwatering. Because the soil holds more water than normal, you will have to make sure that your normal watering patterns do not leave it too saturated.
Mulch, Manure, & Garden Soil
A question often asked by new gardeners is:
"Can I use mulch, garden soil, or manure as a replacement for potting soil?"
The short answer to this question is no.
Garden soil is basically potting soil, but it is made up of worse materials like sand, unfinished compost, and heavier materials.
Mulch is composed entirely of raw wood products, and is meant to be placed on top of soil in order to prevent the evaporation of water. This does not work well with flower pots, and is better suited in outdoor gardens and landscaping.
Manure also does not work well as a base mix for potted plants. It contains high amounts of nitrogen, and should be mixed into soil to prevent it from being too concentrated. This product is better suited for outside gardens as well.
Potting soil, on the other hand, can be used for both flowers and vegetables, and it almost never runs the risk of harming a certain type of plant.
Special Potting Soil Mixes
While the basic mixture of pine bark, peat moss, and either vermiculite or perlite is sufficient for many people, there are two common situations where you might require a different mix.
Orchids require a large amount of drainage, meaning that regular potting soils are generally too heavy for them. If you plan on growing orchids, make sure to look for a specialty potting mix that is specifically meant for this flower.
Cacti and Succulents
Cacti and succulents require soil with increased drainage. You can either look for a potting soil that is meant for these plants, or you can make a mixture of 50% regular potting soil and 50% sand.
Mixing or Making Your Own Potting Soil
Everyone likes to do things differently, and some people find that it works best when they add certain additional ingredients to their potting soil.
Plants are generally forgiving as long as they receive the right amount of water, so feel free to experiment with adding things such as plant clippings, sand, clay, and different types and amounts of fertilizer.
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If you start to run out of one type of potting soil and would like to switch to another, it is also possible to mix them. Make sure that you blend them together as much as possible, and simply use your new creation as you normally would.
The Best Potting Soils
As with many things, there is no one singular "best" potting soil on the market. The best potting mix will depend on what you're trying to grow and how much you want to spend.
That said, here are my top recommendations for potting soils, broken down by brand and by what type of plant you're trying to grow.
Top Potting Soil Brands
Because there are so many different brands available for purchase, we decided to provide you with information on the best potting soils around. Here are the overall top three brands that we particularly enjoy:
- Organic potting mix contains a rich blend of only the finest...
- No synthetic plant foods or chemicals
- Can be used for all indoor and outdoor potted plants
- Enhanced with Myco-Tone water saving formula
- Non selective broad spectrum control of annual and pernnial...
The Espoma Company is a family-owned potting soil brand that has been in operation for over 80 years. They know how to create high-quality organic potting mixes that perform well for almost any type of plant.
Recommendation: Espoma Organic Potting Mix, 16-Quart
- Ocean forest organic soil is ready to use right out of the...
- Ideal for containerized plantings
- Contains earthworm castings, bat guano and micronutrients
- Light texture and well aerated
- Available in 1.5-cubic feet
Fox Farm makes one of the coolest bags of potting mix on the market. But aside from the design, they also include a lot of things that other mixes don't: crab meal, fish emulsion, and a good mix of aerating and water-retention ingredients.
It's a bit more expensive than most, but their Ocean Forest Potting Soil is some of the best you can get.
Recommendation: Ocean Forest Potting Soil
The Best Potting Soil for Specific Plants
As we mentioned earlier, certain plants require special types of potting soil. Here are some popular plants and our favorite potting soils to use with them:
Best Potting Soil For Vegetables
- Organic fertilizer spikes; Time release fertilizer;...
- OMRI listed for organic gardening by USDA; Certified...
- Contains Jobe’s Biozome…the proprietary microorganism...
- Jobe’s Biozome improves soil conditions, helps resist...
- No mess easy to use spikes; Prevents waste and run-off;...
For vegetables, with particular emphasis on herbs and tomatoes, we highly recommend mixing Jobe’s Organics Vegetable and Tomato Fertilizer into one of the two potting mixes that we previously mentioned. This will ensure that your vegetables receive all of the nutrients that they need, and will give them the highest chance at survival.
Best Potting Soil For Succulents
- Organic cactus and succulent soil mix
- Professionally formulated for use with both jungle and...
- Provides the drainage cacti need to flourish; ready to use;...
- Complete package directions provide useful growing...
- This product measures 4 quarts
For cacti and succulents, we recommend using Hoffman Organic Cactus and Succulent Mix. It will ensure that your plants have the proper drainage that they need and will prevent them from being too overwatered.
Best Potting Soil For Orchids
- Multi purpose potting mixture for growing cattleyas,...
- Dynamic combination of western fir bark, hardwood charcoal...
- Promotes healthy, strong growth by providing superior...
- Contains 4 quarts
For orchids, we recommend using the Sun Bulb Better Gro Special Orchid Mix. It is incredibly light and will allow for your orchids’ roots to be well ventilated.
Best Organic Potting Mix
Finally, if you are looking for a potting soil that is specifically organic, this is our recommendation: Black Gold All Organic Potting Soil. It’s healthy, safe for your plants, and perfect for all types of gardens.
Make sure to comment below and tell us your favorite type of potting soil to use, and feel free to ask us any questions you might have!
I’m the founder of Epic Gardening, a website dedicated to teaching 10,000,000 people how to grow plants. I enjoy skateboarding, piano, guitar, business, and experimenting with all kinds of gardening techniques!
Last update on 2018-07-20 / Affiliate links / Images from Amazon Product Advertising API