Dirt. Like it or not, it’s everywhere, often in places you least want to see it. But what is it really? And is there a difference between the dirt that you try to keep from tracking into the house and the soil that makes our plants and trees grow?
Have you ever wondered what the value of potting soil is over other types of dirt and planting media? To find out, let’s take a moment to define what soil really is.
Technically speaking, soil is the term we use to define the rich, dynamic, living substance that serves as the medium in which plants and other living organisms build their ecosystems. Plants need soil to anchor their roots, to provide them with needed water, oxygen and nutrients, and to protect them from deviations in temperature.
While the needs of different types of plants can vary drastically, the fact remains that no matter what you are trying to grow, you probably won’t be successful using just any old dirt. Careful selection and cultivation of the soil is quite possibly the most important aspect of any type of gardening you do, whether it’s an outdoor vegetable garden, or a shelf of indoor potted plants.
Let’s talk about the different types of potting soil that are available for home gardeners and answer some of the most common questions that we hear.
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What Makes Potting Soil Different from Other Types of Soil?
A quick visit to your local garden center may leave your head spinning with all the different options available. But really, all bagged soils can be categorized into one of two groups: garden soil (sometimes labeled as topsoil or compost) and potting soil. So, what’s the difference?
Garden soil is a blend of different bulky organic materials, and its purpose is to amend (improve) existing outdoor soil to create an ideal environment for outdoor flower or vegetable gardening. These materials tend to be sourced from mushroom or animal compost or milling operations.
Potting soil is quite different from garden soil. In fact, it often technically contains no actual soil. Instead, a mixture of peat moss and ground pine bark is mixed with either vermiculite or perlite with limestone added for alkalinity. Plant food is included in the mixture as well for a specific nutrient balance, depending on what is being planted.
Do I Have to Use Potting Soil to Plant My Flowers and Plants?
A bag of potting soil is pricier than the same size bag of compost or topsoil. So why not just fill your pots with garden soil? Seems like the logical choice, right?
As tempting as this might be, do yourself a favor and spring for the potting soil. For one thing, your pots will be much lighter and easier to move around since potting mix is less dense than other bagged soils. In fact, this is exactly why potted plants love this type of soil, because they need loose, well-draining planting medium to survive.
Is Potting Mix Better Than Potting Soil?
You may notice that some bags are labeled potting “soil” while others say potting “mix”. Is one better than the other?
Potting soil can be a somewhat tricky term, and careful reading of labels should be a priority with this one. While the terms can be used interchangeably, some potting mixes with this label may actually contain garden soil as part or possibly all of the medium. This may not be a problem if your pots are located outdoors in a yard or patio, but it’s not ideal for indoor gardening.
Potting mix is purely soilless, with no actual organic soil matter included. This is the most lightweight mixture and should really be your only option for indoor planting since it provides optimal drainage and nutrition for potted plants. You also avoid potentially bringing in undesirable elements from outside, such as bacteria, fungus or insects.
What Are the Key Nutrients that Are Added to Potting Soil?
The three main nutrients needed by all plants everywhere are nitrogen, potassium and phosphorus, although other trace minerals are also important such as carbon, sulfur, calcium and magnesium.
Nitrogen is needed in abundance for plants to produce chlorophyll, which is what makes plants green, and also helps them to produce their own food through photosynthesis.
Potassium, sometimes called potash, helps build the stalks of plants. This one is usually not so abundant in potting mix but can be added in liquid form as needed.
Last, phosphorus helps plants build their roots and seeds.
Different soil mixtures boast different combinations of these nutrients, so it’s important to know what you want before you go shopping. The wrong mix may produce abundant greenery with no flowers, for instance, or super tall stalks with spindly outward growth.
Are Some Potting Soils Better Than Others?
Again, it’s important to read labels and to know what the specific needs of your plants are. Some seemingly fancy mixes may claim to have better nutrients or better drainage than other products, but that doesn’t always mean it’s going to be right for you.
For example, if you know you have a plant that hates having wet roots, then the mix that offers the best drainage is what is going to be best for you. Keep in mind that plant food does need to be added to all mixes eventually anyway since the elements will break down in time and need to be replenished.
Should I Use Potting Soil for My Artificial Plants and Flowers?
If you have artificial plants in your indoor space, you may wonder if using potting soil to fill your containers might make these plants look more lifelike. While this may be true, do keep in mind that potting mix is both expensive and messy and may not even be the best option for securing your fake plants into their pots.
Instead, place your plant into its container and fill in any gaps around it with newspaper or plastic grocery bags or whatever you can find to crumple up. Then make a round cover to fit just inside the top of your pot using cardboard or a plastic plant pot saucer.
When the whole space is filled up and covered, you only need to add a layer of potting soil to the top inch or so of your pot. This method uses much less soil and leaves less mess when you decide to change pots later on.
Should I Use Potting Soil to Plant Indoor Trees?
If you don’t have ample space for a yard, you can still enjoy having trees in your living space. But it’s important to make sure to provide the right conditions so that your tree can grow and thrive.
Just as with any potted plant, trees growing in pots need to be planted in loose, well-draining potting soil so a strong root system can be established. Just remember that like all potted plants, trees growing in pots dry out more quickly than plants in the ground, so you need to check your trees regularly and water them when the soil feels dry about 2 inches below the surface.
We hope this article has helped answer some of your questions regarding potting soil and its uses. If you have any tips on how to use potting soil to grow healthy and thriving plants (or to make artificial plants look realistic) we want to know about them! Share your comments with us below.