When to comes to filling pots and raised garden beds, there are a large variety of choices at the local garden center. Many of us gardeners have type form of container gardens, and if you’ve been in the market for potting soil lately, then you know that it certainly is NOT cheap. Making your own DIY garden soil at home is good idea because it saves money and allows you to know exactly what’s in your own healthy soil.
To add insult to injury, many of the bags of pre-made soil are also only 1-2 cubic feet, may contain weed seeds or large wood chips. The small bag size won’t fill a garden bed or too many large pots, so here’s a quick recipe for homemade potting soil for you DIY gardeners out there!
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Elements in good potting soil
Certainly not all potting soils are alike. You can see at your local store some blends are made for indoor plants, garden beds, and even succulents and cacti. But no matter what type of soil you need, there are some elements that each of these soils have in common.
- Proper drainage: No soil should claim to water log your plants. Good drainage is important for all kinds of garden plants. If soil doesn’t drain and holds on to too much water, your plants run the risk of developing root rot and other complications that will eventually kill the entire plant.
- Organic matter: The soil outside in your yard or in-ground garden is literally alive with bacteria, and this is crucial for the needs of your plants. Having plenty of organic matter in your homemade potting soil is important for this reason.
- Fertilizer: Many brands claim to already include fertilizer to make gardening easier for you, and while this does seem like a good idea, you may want to be cautious about what commercial mixes consider “good quality fertilizer.” These are usually a synthetic mix of nitrogen and ammonium sulfate, which in the long run can have harmful effects on your garden and the larger environment. (Epic Gardening has a wonderful article on this topic.)
Homemade Potting Mix Recipe
I’ve been mixing up my own potting soil recipe before each growing season for use in my vegetable garden for the past five years or so, and DIY potting soil isn’t nearly as intimidating as it sounds. In fact, there are plenty of ways to do it.
I first began using the potting soil recipe from Mel Bartholemew’s book The New Square Foot Gardening. His recipe is very simple, and this helped me to get my footing. Now that I know a little more about available ingredients, I’ve branched out a bit.
- If you’re interested in only using sustainable, local, and/or organic materials for your DIY potting soil recipe, then see my tips at the bottom of the post.
Before the recipe for your own potting soil, let’s learn what are in typical bags of soil mixes from stores like Lowe’s and Home Depot (or your local garden store).
For many of the potting mixes found at the store, even the popular green bag offering “miracles,” they include a mix of traditional potting mix ingredients: perlite, sphagnum moss, compost, fertilizer, and sometimes sand. But the unknown elements listed, such as “wetting agents” and “forest products” make me wary, and some cheaper varieties may even have larger chunk of pine bark.
While I won’t say that all of these bagged mixes aren’t good soil, when you make your own mix, you can choose the best ingredients that will allow you to make a large quantity and also be specific to your gardening needs. If you need to grab a bag of potting soil from the store in a pinch, check my recommendations at the bottom of this post for good potting mix.
Materials You’ll Need for DIY Garden Soil
Mixing up your own potting soil mixture is simple and easy, I’ll skip the mystery ingredients and stick to the basics. Here are the primary components of my potting soil recipe.
Sphagnum Peat Moss /Coconut Coir– Peat moss comes from peat bogs (primarily found in Canada) where moss and other materials decompose. This decomposed moss is then harvested and packaged for use by gardeners all over the US and Canada.
I have recently read articles about the environmental impact of peat moss harvesting being called into question. Because of this, some gardeners have been making the switch from peat moss to coconut coir. Coconut coir is a product produced from the coarse fibers on the outside of coconut shells. The coir comes in dense blocks that once moistened will expand. Both peat and coco coir are soil amendments that retain moisture, so they’re excellent for use in gardens and potting mixes.
Perlite/Vermiculite: The names sound a little intimidating, but if you’ve ever purchased pre-made potting mix then you’ve probably seen the white perlite chunks in the mix. Perlite is volcanic glass heated to an extremely high temperature. Once heated, it expands and pops into smaller pieces upon cooling.
The small pieces are incredibly lightweight and help to retain moisture and nutrients for plants to use. Vermiculite forms from a group of minerals that, like perlite, are heated to high temperatures. The high heat creates long strands that are then broken up into various granular degrees (coarse, fine). And like perlite, it works well for water retention, so it’s commonly used by gardeners.
Which to use? Perlite drains more effectively than vermiculite, so if you live in an area that gets plenty of rain, especially in the summer, this would be the choice for you. I live in the southeast, which can have dry spells throughout the summer, so I choose vermiculite.
Compost is pretty self explanatory, and it can come from homemade compost or from bags purchased at the store. I like to have a variety of composted materials, so I typically use some of my own compost and a bag or two of Black Kow compost. (Learn how to start composting!)
You could also use worm castings as an organic fertilizer added to your garden soil mix. Decomposed organic matter, compost gives plants a rich nutrient source. What many gardeners compost will primarily contain broken down veggies, lawn clippings, and paper. What can be purchased at the store may include composted manure, and since we don’t have cows or chickens, I’ll purchase a bit to throw in my potting soil recipe.
Decomposed organic matter, compost gives your plants a rich nutrient source. What many gardeners compost will primarily contain broken down veggies, lawn clippings, and paper. What can be purchased at the store may include composted manure, and since we don’t have cows or chickens, I’ll purchase a bit to throw in my potting soil recipe.
Coarse sand: If I have some sand on hand, then I will add this component to my own potting mix. This element does help aerate the mix, and if you don’t have coarse sand, fine sand can easily be substituted.
How to Mix Your Own Potting Soil
First determine how large of a batch of potting soil you will need. Are you going to use this for a few container plants, or will you be filling garden beds? Once you’ve assessed how much you’ll need, you can proceed with gathering materials and putting together your perfect soil!
I typically use the ratio of equal parts peat moss, vermiculite, and compost for DIY garden soil. There are lots of variations out there that use these same three ingredients but in different ratios. I can also tell you there is grace in how much of each ingredient to use. You certainly won’t kill your plants if you use more peat moss than compost, etc.
For best results if you’re creating a small batch of potting soil, use a large rubber tub (with a lid) or a gallon bucket if you only need a pot’s worth. Place all of your ingredients in the bin and mix well. If your peat or coir fiber is dry and dusty, use a spray or two of water to keep the dust to a minimum. Your potting soil will then be ready for use whenever you need it if you keep the lid on tight.
For filling an entire raised bed, I simply place all of my ingredients in the raised bed itself, or mix the components on a large tarp. Then using a garden hoe or bow rake, I’ll mix the potting soil recipe right in the bed, or lift the corners of the tarp and mix. (Want to make your own Raised Bed? Check out my full post with instructions!)
If you make a large batch of potting soil, using the above method, you can use a plastic tub with an airtight lid to store any extra. Then you’ll easily have soil on hand for using throughout the season. Consider making a batch in early spring to use as you replenish containers and pots for the spring and summer. This will save you trips to the garden center and lots of money as well!
Whether in a container or in a raised bed, this potting mix should last for years. I may add in more compost each spring to give it a nutrient boost, and/or I toward the end of the fall to keep the soil rich. If your soil is going into a raised bed, consider having the soil tested the following year, so you’ll know exactly how to amend it to keep your plant growth consistent and your garden thriving.
Homemade potting soil ideas
If you’re looking to create your own potting soil at home, and you want your materials to all be locally sourced (i.e. not from Canadian peat bogs or from volcanic rock… no volcanoes near you), then here are some ideas:
- Use a mix of local top soil and compost. Check out a local landscape supply store to purchase these items in bulk.
- Find a local manufacturer of potting soil and ask them what’s in their soil. (We have a local company, Daddy Pete’s, that produces a great product.)
- Consider adding a bit of sand to your soil mix for better drainage. Use topsoil from your own yard and mix in rich compost and a bit of sand.
Fertilizers for your diy garden soil
If you’d like to add a non-synthetic fertilizer to your potting soil to make it more like a bagged mix (but of better quality of course!), then consider these quality options:
- Espoma Plant Food: I love this brand of fertilizer and you can choose the food that’s appropriate for the types of plants you’re growing. For example, there’s a specific fertilizer for flowers, tomatoes, and trees and bushes.
- Down to Earth Fertilizer: While I haven’t used this brand myself, I’ve heard from other gardeners how much they enjoy it.
Have you tried mixing your own potting soil? Are there any additions you think give great results in your garden and containers? I’d love to know what you’ve tried and what has worked for you. Have a great week and happy gardening!
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