There’s something about gardening that can be a bit elusive to gardeners — new and experienced ones.
Everyone knows that plants need three main things to live: sunlight, soil, and water.
Of those three major elements, soil can be one of the most confusing and complicated to figure out.
Where you live your soil might be too sandy or it might be too rich with clay. It could be too alkaline or too acidic. It might be lacking nutrients like phosphorus, nitrogen, or potassium, or it might have levels that are too high.
If you’ve ever tried to buy soil at the store, it can also be a complicated experience. There’s gardening soil, potting soil, seed starting soil, raised bed soil, and more.
Then you begin to talk about the components of these soils such as peat moss, perlite, and vermiculite and things get even worse.
There are so many different types of soil!
Do you have to be a scientist or a master gardener to grow plants in your garden? Nope. You don’t. But, guides like these can help you understand gardening and the soil needed to grow your precious plants a little better so you can improve year to year.
Are you ready to learn about the different types of soil? I know I am! Let’s get into it.
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What Are the Different Soil Types?
Those of you who live in rural areas or places with a backyard have soil to grow a garden. Depending on where you live, your soil will be a different type. There are five major types of soil that we will talk about here:
Sandy soil tends to be acidic and low in nutrients. This type of soil is light and drains easily, and it’s usually found in arid or semi-arid areas. Sandy soil will remind you of a day at the beach. If you pick it up and squeeze it, it will easily run through your fingers.
Sandy soil is made up of broken up pieces of rocks that have been reduced to granules.
The best plants for sandy soil
- Black-eyed Susan
- Russian Sage
Now that doesn’t mean you could watch out to the beach, plant some squash, and watch it thrive. Sandy soil is low in nutrients that plants need, so you need to incorporate organic material so your plants can grow.
How to improve sandy soil
- Add 2-4 inches of organic material. Organic material includes manure, compost, grass clippings, mulches, and more.
- Grow green manure or cover crops. To improve soil and reduce weeds, some gardeners grow what’s called green manure or a cover crop. These plants are grown in the off-season or as part of a crop rotation plan, and they are tilled back into the soil rather than being harvested.
With sandy soil, you will need to routinely add new organic material. It’s not a one-and-done situation. You will likely need to add more mulch/organic material every year or maybe even several times a year.
Clay soil is very dense and doesn’t drain well at all. It can be difficult to cultivate because it’s heavy and doesn’t turn over easily. One benefit of clay soil is it tends to be high in nutrients, but things struggle to grow in it because they have to fight to push through the dense material of clay soil.
If you pick up clay soil and squeeze it into a ball it will retain its shape. You will also recognize it in your garden because it will be hard to dig in.
The best plants for clay soil
- Grasses like Indian Grass, Fountain Grass, and Canadian Wild Rye
How to improve clay soil
Personally, I’d rather have sandy soil than clay soil. It’s hard to manage clay soil and it’s a lot of work to plant your plants. It’s just not ideal for a flower or vegetable garden. If this is the type of soil you have, don’t fear… it can be improved. Here’s how:
- Add organic material. Organic materials like compost, pine bark, and gypsum can make clay soil less dense and improve drainage.
- Don’t add sandy soil to clay soil. Some people may recommend adding sandy soil to offset the problems with clay soil, but this won’t help. The Illinois Extension explains why this is a bad plan, “When sand mixes with clay, it creates a soil structure akin to concrete. To create a real change in a clayey soil structure, you would need to add a 1:1 ratio of sand to clay. Considering the actual volume of clay soil underfoot, that equates to a lot of sand.”
- Grow cover crops or green manure.
- Avoid walking on wet clay soil. When it rains outside, don’t walk around your garden. This will only compact the clay soil and make it harder to manage.
- Aerate the soil. Using a gardening fork you can manually add air pockets to the soil which can help it to aerate and become less compact.
- Try a no-till garden. Tilling clay soil can worsen the problems. You may want to try a no-till method with a garden that has a lot of clay in the soil.
Silty soil is good for a garden. It’s not as nutrient-rich as clay soil, but it does hold moisture and has a higher nutrient content than sandy soil. Silty soil is somewhere between clay and sandy soil, with particles that are bigger than clay particles but smaller than sandy ones.
Some people describe silty soil as feeling soapy or slippery when wet or like baby powder when it’s wet. Like clay soil (although not as severely) silty soil can have poor drainage and can become hard and compact when wet. It’s also prone to creating a crust on top which can make it hard for plants to break through.
The best plants for silty soil
- Birch trees
How to improve silty soil
- Add organic material
- Don’t walk on silty soil when wet or till unnecessarily. Avoiding overworking the soil can help keep it from becoming too compact.
- Grow cover crops.
- Don’t overwater the soil.
- Aerate or turn over the soil.
Chalky soil, also known as basic soil, is very alkaline (we’ll talk about the difference between alkaline and acidic before). This soil is made up of broken-down rocks that are soft such as lime or calcium carbonate. Chalky soil drains well and has a higher nutrient content than sandy soil, but plants have a difficult time absorbing the nutrients because of the high alkaline content. This type of soil is not ideal for vegetable gardens and requires quite a bit of cultivation to make it useable. It is also often full of stones.
If you place some of this soil in a jar and add vinegar to it, it will become frothy.
The best plants for chalky soil
- Californian poppies
- African lily
How to improve chalky soil
- Introduce a lot of organic material
- Water often. Chalky soil drains well which means it doesn’t hold water well for plants that need ready access to water.
- Plant cover crops
Loam soil is often considered the best type of soil for gardening. It’s a good mix of sand, silt, and clay making it high in nutrients and able to retain moisture. Compared to clay-only soil it’s also easy to cultivate. Sometimes loam soil is confused with topsoil, but topsoil refers to where the soil is located whereas loam soil is the type of soil it is.
The best plants for loam soil:
- …let’s be real… most of the things you want to grow will like this soil
How to maintain your loam soil
Loam soil is the ideal, so it’s more a matter of keeping it the way it is. Here’s how:
- Continue using organic materials. Soil can become depleted from use, so adding organic material to your loam soil is still important.
- Grow cover crops
How to Identify Different Types of Soil
There are several ways of identifying what type of soil you have. For instance, if you have soil that has a lot of clay in it, you may notice that when it rains the garden pools up and doesn’t absorb the water well. Sandy soil may readily soak in a lot of moisture before puddles start to form.
You can also pick up the soil and squeeze it in your hand. Soil that’s clay-heavy will easily form into a ball, even if it’s not very wet. Sandy soil will fall apart and flow through your finger if you try to form it into a ball.
There’s another method called the jar test which requires a bit more effort but can give you a better indication of what type of soil you have. Most people won’t have 100% of any single type. You probably have a mix of different types with one that’s more dominant. The jar test can help you determine how much you have of each one.
To do this test you will need:
- Get soil from your garden. You can take several samplings from different locations in your garden if you have a large garden. Make sure you dig at least 6 inches deep to get a good sampling.
- Remove organic materials and rocks from your soil sample(s). You can sift it through a kitchen strainer to help break up the soil and make the process go more smoothly.
- Fill your jar with soil from your garden. Fill the jar about 1/3 to 1/2 full.
- Add water to the jar. The jar should be about 70%-90% full of water. Leave some extra space so you can shake it up.
- Add a drop of dish detergent or a tablespoon of powdered detergent. This helps separate particles from your soil.
- Shake vigorously. You really want to mix it up.
- Set the jar down and allow the soil particles to settle.
- Sandy parts will settle first, and you can measure the height of the sandy soil after a few minutes.
- Next, the silt part will settle. This takes about two hours. Once this has formed, you can mark that on your jar.
- Last, the clay will float to the top. This often takes several days to form. Above the sand, silt, and clay will be water, and any organic material left in the soil will float to the top.
- It will require a little bit of math at this point. Don’t panic. The math is not too difficult… I know because math is not my strength and this is doable. Here’s how to do the math:
- Measure the total height of the soil (the top of the soil in the jar. Do not include the water in your measurement)
- Measure the height of each individual layer. Find the height of the sand, silt, and clay.
- Divide the individual heights by the total height of the soil to find the percentage. For instance, if the total height is 100mm, and the sand layer is 50mm, your soil would be 50% sand. Of course, that’s very simple math and your actual measurements won’t be as clean cut.
Here it is a bit easier to read:
When you’re done getting your percentages, go to the USDA soil texture calculator to determine what type of soil you have. You will input the percentage of sand and clay you have, and it will show you on a pyramid what type of soil you have. Note: You don’t need perfectly split percentages of soil to have loamy soil.
In case you were wondering, that pyramid that shows you what kind of soil type you have will look something like this:
It looks really complicated, but it’s a simple graph that will let you know what type of soil texture you have, or which of the different types of soil you have in your garden. As you can see, your soil can be 50% sandy and 10% clay and still fall within the “loam” category.
Here are a couple of videos that talk about how to do the soil jar test if you’re a visual learner.
What Nutrients Do You Need in Your Soil to Grow Plants?
We talk about your soil needing organic material and nutrients, but what nutrients do your plants really need to grow?
There are six main nutrients your plants derive from soil that they need to thrive. Those are:
Here’s what each nutrient does for your plants:
- Nitrogen may be the most important nutrient found in soil. It helps give plants their healthy green color and energy to grow and produce fruit.
- Phosphorus helps plants grow roots, seeds, fruits, and flowers. Phosphorus also contributes to a plant’s ability to fight disease.
- Potassium is considered the second most important nutrient. This nutrient helps with photosynthesis and other physiological processes of plants.
- Magnesium. Without magnesium, the plants would not be able to use chlorophyll to collect energy from the sun.
- Sulfur helps plants form amino acids, protein, and oils and is also an important nutrient in the photosynthesis process.
- Calcium is essential for supporting the cell walls, maintaining pH levels, and improving water infiltration. It can also make the plant more disease resistant.
What Happens to Plants With Nutrient Deficient Soil?
Common signs of plant malnutrition in plants are:
- Yellowing leaves
- Light green plants (not dark and lush)
- Spindly plants
- Poor development
- Purple or bronze underside of leaves or leaves are speckled
- Leaves look scorched
What is Acidic or Alkaline Soil?
Another term you may have come across when it comes to soil health is acidic or alkaline soil.
All soil ranges from acidic to alkaline. This range is measured in numbers from 1 to 14 and is referred to as the pH. Soil that is lower than 7 is considered acidic and anything above is considered alkaline.
Some plants prefer more acidic soil while others prefer soil that is more alkaline. Most plants grow best in a neutral range of about 6.2 to 7.0.
What is a Soil Test Kit?
The best way to find out if your soil is alkaline, acidic, or lacking in nutrients is to test your soil. You can get a sample and have someone else test your soil, or you can do it yourself with a home soil test kit.
We have a whole blog post explaining how to use a soil test kit if you want to do it yourself.
A soil test kit like the one pictured above will tell you how acidic or alkaline your soil is, and it will let you know if your soil has a healthy amount of nutrients.
Our results when we did it showed us that our soil was a good pH level, perhaps a tad high in phosphorus, and low in potassium and nitrogen. Nitrogen was especially low.
How to Increase Nutrients in Different Types of Soil
You can improve your soil in a number of ways. The main things you can use to make your soil have a higher nutrient content are:
- Chemical fertilizers
- Cover crops or green manure
- Compost. One thing you can do to improve your soil is to start a compost pile. Organic matter like leaves, garden clippings, wood chips, cardboard, and discarded kitchen fruits and veggies can help put important nutrients back into your soil. Once these materials are broken down and turned into soil, they can be placed in your garden.
- Manure. Manure can be another fantastic way to add nutrients to your soil. It does take some research to know what works best for your garden. For example, chicken manure is high in nitrogen so you should compost it a long time before adding it to your garden because the high nitrogen can burn or kill your plants.
- Vermicompost. Vermicompost means using earthworms to create natural fertilizer in your garden. You can add worms right to your soil or to a compost bin to create fertilized soil that can later be added to your garden.
- Mulch. Adding hay or straw to your garden to make a deep mulch can help retain moisture and add nutrients to the soil.
- Fertilizer. If you’re planning on starting a totally organic garden you may not be interested in using chemical fertilizers. There are a LOT of different thoughts about it and people are all over the map. However, if you’ve tested your soil and you’ve discovered that it’s low in phosphorus, potassium, or nitrogen, many people choose to add bagged fertilizer to help. You can also purchase organic fertilizer which is a good alternative to synthetic fertilizer.
- Cover crop or green manure. Cover crops or “green manure” are plants that are grown in the soil specifically meant to enhance the soil. Other reasons people grow cover crops are to slow erosion, to reduce weeds, pests, and disease, and to increase water filtration. Some cover crops like legumes increase nitrogen in the soil.
- Gardeners might grow a cover crop during an offseason or they may allow a garden space to grow cover crops for a full year like farmers who utilize crop rotation.
- Once these cover crops are finished growing (and before they turn to seed) they can be tilled back into the soil to help revitalize the soil.
- Some cover crops are left as they are and don’t need to be tilled into the soil.
- Examples of cover crops are:
- Rye grass
- Winter rye
- Red clover
How to Improve the pH Balance in Different Types of Soil
Before you decide to change the pH balance of your soil, first figure out what you want to grow. The plants you’re interested in might want more acidic soil, or they may do better in more alkaline soil.
An example of some plants that like acidic soil are:
- Sweet potatoes
An example of plants that like alkaline soil are:
- Lily of the Valley
- Pole beans
If the results of the test show that your pH levels are too alkaline or too acidic to grow the plants you’re interested in growing, there are some things you can do.
For soil that is too alkaline, there are a few things you can do. It’s best to make these adjustments in the fall, but you can add things to your soil at other times of the year too.
- Sulfur. You can add sulfur to your soil to lower pH levels, but the results will not be immediate. Try adding it in the fall after your last harvest and waiting until the spring to test your soil again. Sulfur lasts longer than some other options so you may want to try this one first.
- Iron sulfate. This is a fast working solution but doesn’t last as long as sulfur. It can also be damaging to plants if overused.
- Sphagnum peat moss. You can add this peat moss to your soil and till it in. The bonus of this option is it will also add organic material to your garden. You can also use it as a mulch around your plants if you’re able to work it a couple of inches into the soil.
If your soil is too acidic, you can try:
- Limestone. This is by far the most common way to raise the pH level of your soil. Don’t use too much limestone as it can harm your plants. It’s best to add this in the fall and till in or work into the soil up to 8 inches. How much limestone you use will be determined by how acidic your soil is.
- Wood ash. Wood ash can temporarily raise the pH level of your soil. This is fast-acting but will need to be repeated. Don’t use wood ashes from wood that has been chemically treated.
Different Types of Storebought Soil
Anyone who has had to buy soil at a local box store to grow seeds, pot a plant, or start a garden knows what it’s like to walk through the gardening section and see the plethora of soil types. Organic soil. Topsoil. Potting soil. Seed starting mix. If you’re new to gardening and even if you’re not this collection of soil types can lead to a lot of confusion. I mean what in the world is top soil, right? And what type of soil is best for what type of project??
I know this confusion all too well. I am trying my hand at winter sowing this year… which basically means growing seeds in milk jugs outside. I did some research beforehand and a lot of places suggested using potting soil to start the seeds. However, locally two separate places said we should start with seed starting soil and one place suggested seed starting soil and then transfer to potting soil once they’ve sprouted.
I thought… I can’t be the only one struggling with this. So without further ado, here are the different types of soil that you can buy at the store and their primary function (and what they’re NOT for).
Perhaps the most generic of all soils is topsoil. What’s topsoil, right? Isn’t everything we grow plants in top soil? Well let me stop your right there. If you see this at Lowes or Home Depot, do not pick it up for your garden. This would be more useful in say in filling holes or leveling the ground before putting in your chicken coop. It ain’t for growing anything.
Garden soil is as you guessed it… for your garden. Your basic garden soil will be pre-mixed with organic material and nutrients for your plants, and can help improve the soil quality in your home garden.
You should not use garden soil in potted plants or as a seed starter. Garden soil retains too much water and becomes too compact for your in-pot plants or seeds.
Potting Soil or Potting Mix
Not all potting soil or potting mix is made the same, but the intended purpose is for plants that are already established inside pots.
A potting mix will be able to retain water, but also allows air space for roots to grow. When you purchase potting mix you shouldn’t run the risk of having soil that contains pets, weeds, or disease.
Potting mix is sometimes called “soilless” because they are not made up of the soil you have in your garden. Most potting mixes have a variety of organic and inorganic material such as:
- Peat moss. Peat moss is harvested from peat bogs and is an organic material that doesn’t fully decompose.
- Pine bark which of course comes from pine trees is often found in potting mixes and also in mulches.
- Perlite are those tiny white balls you find in commercial potting soil. They look sort of fake, but they’re actually minerals that helps soil aerate better and drain efficiently.
- Vermiculite is another mineral often found in potting soil and it looks like little gray or brown flakes. It’s often included in these soilless mixes because it doesn’t rot or mold and it can help retain moisture and nutrients. It’s also helpful for aerating the mix.
- Coir is an organic material that can easily be confused for peat moss, but comes from a source that’s easier to renew: coconuts. Some people prefer this over peat moss because it’s pH balance is within a good range for most plant types. Some gardeners are concerned that peat moss will eventually be used up and isn’t a sustainable source.
When you purchase potting mix you’ll likely notice there is a wide variety of types. Potting soil may or may not be “soilless” but all “potting mixes” are made of the types of materials listed above and are completely soilless.
Some of the potting soil types you might see are:
- Micracle Gro Potting Mix which have the typical potting mix material plus fertilizer.
- Orchid potting mix good for orchids because it drains well.
- Cactus potting soil is also good for drainage and probably contained fertilizer
- Outdoor potting mix formulated for both indoor and outdoor use, and may contain fertilizer or pellets that control moisture.
- Organic potting soil/mix. Made from organic materials probably has manures, composts, or earthworm castings in addition to things like perlite or peat moss.
- African violet mix provides more aeration and drainage.
Seed Starting Soil/Mix
Typically with seed starting mix you’re talking about something that’s soilless. A good seed starting mix is light and fluffy and easy for seeds to break through and develop early roots. A seed starting soilless mix will also help protect new seeds from fungus, disease, weeds, mold or pests.
It’s similar to potting mix, but it’s lighter and finer in texture and won’t have fertilizer like some potting or gardening soil would.
Once a plant reaches the seedling stage, or when they’ve developed one to two sets of their true leaves, it’s a good time transplant them into the garden or into a pot with potting soil.
Raised Bed Soil
You can think of raised bed soil as a mix that lands somewhere between garden soil and potting soil. It’s not as light as potting soil, but it’s not as heavy as garden soil. Raised bed soil has some of the drainage properties that you’ll find in potting soil, but it will also have real soil like gardening soil.
Of the types of soil, this is the one I had the most trouble finding information on. I believe that some people make their own type of raised bed soil by mixing compost, garden soil, and potting soil (or potting soil ingredients) together.
Do You Have Any More Questions About the Different Types of Soil?
What did I miss? What information was helpful, and what do you have more questions about? I learned so much about the different types of soil as I wrote this post, and I know for many of the points there could be a lot more said. I hope this gave a good overview of the many facets of the dirt we grow our plants in, and may help troubleshoot some of the issues you’ve experienced in your garden.
I hope you have a wonderful gardening season and that you enjoyed reading all about the different types of soil.
Until next time, take some time to grow, build, or make something. That’s it from us at the Making Life.