How to Make DIY Potting Soil
Having potting soil on hand is essential for any plant owner or gardener. It is nice to keep potting mix around the house because you never know when you’re going to need it. That’s why I like to make DIY potting soil. We use potting soil in and around our house to start seeds, grow countertop gardens, transplant houseplants, root cuttings, and more.
I often need potting soil because one of my cats has knocked over a house plant and broken the pot! We will show you how to make DIY potting soil so you can save money and always have what you need on hand for your garden and house plants.
Why Make Potting Soil?
If you’re like most of us here at Makers Make Stuff, you probably have plants or like to grow some of your food. We like to do things ourselves because it’s fun and rewarding. But from time to time, making things yourself can be healthier, and even cheaper.
Affordability is one of the biggest reasons we encourage you to make DIY potting soil. You can cut your gardening/plant budget significantly when you make your potting soil.
Most Commercial Potting Soils Contain Strong Fertilizers:
Another significant benefit of making potting soil yourself is customizing (or cutting out) the fertilizer in your soil. Most commercial potting soils contain strong fertilizers. These products are marketed to the novice houseplant owner. These potting soils are too strong to start seedlings, transplant cuttings, and they can even kill some common houseplants!
By avoiding commercial potting soils, you can avoid strong fertilizers that won’t help your plants and can even hurt them. Most plants require a customized feeding schedule anyway.
So, to save some money and the health of your plants, let’s make potting soil!
DIY Potting Soil Recipe:
Contrary to popular belief, potting soil doesn’t contain any soil from outside. While potting soil or potting mix does contain natural elements as a medium to grow plants, you can’t dig it up from outside. What you have in your backyard under your grass is “topsoil,” that’s full of weed seeds and other things that can help or hurt your plants. The soil outside your home is too dense to use for indoor/outdoor potted plants or as a seed starting mix.
Before we get to the ingredients to make your potting soil, let’s talk about a few physical characteristics your potting soil needs to be the best growth medium for your plants.
Potting soil needs to:
- Drain well
- Retain moisture
- Stay fluffy and lightweight
- Breakdown slowly
- Be easy to handle (doesn’t clump or stick together in big hard chunks)
Some plants require more or less of these individual characteristics. For example, a cactus plant needs a really well-draining soil that doesn’t retain as much moisture. At the same time, a palm plant that likes to be moist might want some extra water retention capability in its soil.
Once you have the basic ratio of these elements, you can tweak them a little, depending on what type of plants you grow.
Ingredients for Potting Soil:
Coconut core is the by-product of the processing of coconuts for coconut products. This product adds bulk and weight to your mix. The coconut fibers add nutrients to your potting mix and retains water well. Coconut core breaks down slowly and keeps your potting mix light. You’ll find coconut core soil in compressed bricks, and they increase in size when moistened and broken apart by hand. Coconut core is more sustainable and doesn’t break down as quickly as peat moss, which many commercial potting mixes use.
Perlite is the small white balls you find in commercial potting mixes. Made from volcanic rock, aerates your potting mix adding drainage and air space in your potting mix. Perlite also holds four times its weight in water adding water retention to your potting mix.
Vermiculite looks like large grains of sand. It’s a mined mineral that adds calcium and magnesium to your potting mix, which are essential nutrients for plants. Vermiculite increases drainage and moisture retention of your soil.
Sand (Optional of extra drainage):
Sand increases the drainage of your soil. While you want your soil to hold some moisture for your roots, you don’t want your roots sitting in water (this can cause root rot). Sand can help water drain quickly through your soil, keeping your plants’ roots safe.
You’ll notice that I’m not giving you amounts yet.
Depending on how much or how little potting soil you’ll need, I will provide you with a ratio rather than exact quantities. While I work in gallons or buckets to make potting soil for my plants (indoor and outdoor), you might be working in cups if you have fewer plants than I do.
The ratio to Make DIY Potting Soil:
- 3 parts Coconut Core
- 1 part vermiculite
- 1 part perlite
- 1/2 to 1 part sand (If you are working with succulents or cacti, increase the sand to two parts.)
If you wanted to make a just over a gallon of potting mix, your recipe would look like this:
- 6 cups of coconut core
- 2 cup of vermiculite
- 2 cup of perlite
- 1/2-1 cup of sand.
A part can be anything you use to scoop or measure your ingredients. A shovel full, a cup, a bucket, anything really.
Combine all of these and mix well with your hands.
Be sure to pre-moisten your potting mix before planting. You don’t want to start with a dry potting mix.
For larger applications, you can mix your potting mix into a large garbage barrel or a wheelbarrow and use a strong shove to mix it.
Where’s the Compost?
Compost is full of beneficial bacteria and nutrients and is excellent for the health of your plants. We leave it out of our potting mix recipe because it can be too intense for young seedlings or small plants. If you are working in your garden or with mature potted plants, you can mix 1-2 parts of your homemade compost into your potting mix for some added nutrition and water retention in your soil.
Ways to Use DIY Potting Mix:
- Layer some into your hole before planting your seedlings in your garden.
- Use as your primary soil for outdoor container gardens or raised beds.
- Grow herbs or vegetables on your kitchen counter using DIY potting soil.
- Use as your primary potting mix for house plants. Don’t forget to add extra sand for cacti and succulents.
- Start seeds indoors for your summer garden.
- Use DIY potting mix to repot your indoor plants when your cat knocks them off the windowsill.
We prefer to leave the fertilizer out of our potting mixes because many plants require different nutrients. Most plants need nitrogen, phosphorus, and potassium in different ratios. Flowering plants, for example, need more potassium to encourage flowering, while foliage type plants require more nitrogen. Some plants are heavy feeders and need to be fertilized more often during the growing season that other types of plants.
It’s easier to hold off on adding fertilizer to your potting mix and instead create a customized fertilizing schedule for your plants based on their individual nutrient needs.
The Bottom Line:
You can make a DIY potting mix to save yourself money and avoid strong fertilizers when it comes time to care for your indoor plants or start your garden.