Not all soil is created equal and while it can be confusing, it is important to know what your plants prefer. We’ll go over the differences between potting soil and compost and what they are ideal for.
Should you use potting soil or compost: Potting soil is made up of peat moss, coconut coir, vermiculite, and perlite to create a light and airy soil that drains really well. It is best used for growing seedlings and container gardens. Compost is a mixture of brown and green organic matter and may include grass clippings, vegetable scraps, and even worms. It is best for adding to an existing garden for a balance of nutrients.
Difference between potting soil and compost soil
Potting soil is actually not often made of soil at all. Instead, it is a mixture of organic materials that are made to provide the best medium for growing seeds.
Potting soil can be made of different substances but is usually a combination of coconut coir, pine chips, and pet moss. It will also have perlite, vermiculite, or sand mixed in.
Potting soil is made to be light and airy so that water can drain well. It is also full of nutrients so if you are using potting soil for seedlings, you won’t have to add any extra fertilizer.
Compost is also an organic mixture but is made from many different objects. Balanced compost will be a mix of brown items, such as decaying leaves, and green items, such as vegetable scraps.
While you can make compost in your backyard, which many gardeners do thanks to a large black bin that speeds up the decomposition process, potting soil is specially made and needs to be store-bought.
Furthermore, while potting soil is used as a starting mix with plants, compost should be routinely added to your garden as a way of steadily introducing nutrients to the area.
Types of potting soil
All-purpose potting soil
The most common type of potting soil is created for a wide variety of plants. It will include typical organic ingredients, such as coconut coir, peat moss, and perlite.
If you are growing orchids, you will need a special potting mix as they don’t grow in soil. Instead, the potting mix will have bark chips and charcoal to ensure there is proper drainage.
Seed starting mix
Those that are starting their seedlings inside will want a nutrient-dense potting mix. It is completely sterile, so there is no need to worry about bacteria and will include a mixture of peat moss, vermiculite, and perlite.
Types of compost
This is your most basic compost and one that is often found in backyard gardens. You can start with any sort of container but those made from black plastic are the best as they warm the compost better, making it easier to break down.
With plant-based compost, you can add a variety of organic materials, such as vegetable and fruit peels, grass clippings, and leaves. You can even add coffee grounds and newspaper clippings.
As worms eat their way through organic matter, they leave behind casings, which is just a better word for worm poop. Worm castings can then be added to your garden as they are highly nutritious.
You can use any sort of worms but the most popular are red wigglers, which you need to purchase beforehand. Then, feed normal compost materials to these worms, such as kitchen scraps and grass clippings.
Also known simply as manure, you can collect droppings from cows or horses. Herbivores produce manure that is safe to use in your garden while non-herbivore animals can carry bacteria in their manure.
If you don’t have a compost bin in your backyard, you may be able to find compost in your local city. This is often made from yard waste pickup and may also include bio waste, although it is processed in a safe manner.
Potting soil pros
Specific needs of plants
You can find potting soil for a wide variety of plants, including succulents, orchids, and African violets. These potting soil mixes will work specifically for these varieties, so you don’t have to worry if they will survive.
There is even potting soil that is made for seedlings, so you know you can start your plants off solidly. They will then be healthy enough for transplanting so you don’t have to waste your time and money.
Moisture retention and drainage
Thanks to the components of potting soil, you won’t have to worry about pooling water. Instead, the light ingredients, not to mention substances such as perlite, will ensure the water drains away from the delicate roots of your plants.
Very few plants like their roots to get wet as this can lead to rot and soggy roots that quickly dry. Having potting soil mixed in with normal topsoil can also increase the drainage aspect.
Potting soil cons
As you aren’t able to make your own potting soil, at least not easily, you will need to purchase bags of it. This can add up quite quickly.
Potting soil, especially for specific plant needs, is only sold by the bag so you can’t even get it in bulk at a cheaper rate. If you have a lot of plants that require potting soil, be prepared to spend a lot of money.
Needs extra nutrients
Potting soil is great when you’re first starting out with your plants. But pretty soon you will need to amend the soil with extra fertilizer.
For seedlings, this will need to be a liquid fertilizer as the roots are too delicate to be dug around. Unfortunately, not only is adding fertilizer time-consuming but it can also be costly.
Compost soil pros
While your compost won’t technically be free, it is can be made from items you would otherwise throw away, so it can seem like it is actually free. These items can include vegetable scraps, coffee grinds, and old plants from your garden.
Add in grass clippings and leaves, and you suddenly have a place to put all the natural clutter from your garden. You can even add newspaper clippings as the ink is made from vegetables.
Compost can take a little work at first to find the right ratio between green and brown items but once you get it down, you can be assured that your compost will have all the nutrients your garden needs. You won’t have to worry about adding more nitrogen, phosphorus, or potassium unless you are planting something that has very specific needs.
Compost soil cons
Balanced compost that you are diligent about turning will be ready in just a few weeks. But for most people, it can take a few months.
Compost needs to be turned every few days and you need to monitor its moisture level. You also need to constantly add layers of brown and green items.
In the course of everyday life, most people forget about their compost. This is fine, as it will still break down, but you might not have compost ready when you most need it.
It can be tempting to add weeds to your compost when you are cleaning up your garden. You might assume that it will be warm enough in the bin to kill off any seeds and stop them from spreading.
However, compost shouldn’t get too hot, or else it will kill off all the naturally good microorganisms inside. If you accidentally put weeds in your compost, you may find tons of weeds popping up all over your garden, leading to a massive headache.
When to use potting soil?
Potting soil is primarily used for new plants and seedlings. It has excellent drainage so if you are using a container for planting, it will ensure the plants don’t become soggy.
You can purchase special potting soil for plant seedlings which is an excellent way to ensure they start out strong. You should also use potting soil for more exotic plants, such as orchids.
When to use compost soil?
Compost soil is best if you have an existing outdoor garden. You can add compost to the topsoil in your garden so it will be full of nutrients.
Then, you can side-dress your garden in the spring and fall by adding more compost. Compost will slowly release nutrients into the soil, giving your plants all that they need to grow and thrive.
How to know which soil you should use?
Basically, if your garden is home to basic plants and vegetables, then compost soil is what you need. It is all-purpose and will have a balanced mix of nutrients.
However, if you have plants with very specific needs, then you should use potting soil. You can find potting soil for tropical plants such as succulents that will be designed to allow water to drain better.
Plants need some form of soil to grow and it can be overwhelming to know which to use. Compost is made of organic matter that has broken down and is great for all-purpose gardens. Potting soil is made from a combination of coconut coir, peat moss, and perlite, and is better for seedlings and tropical plants.