What is DIY potting soil

Before talking about our favorite DIY potting soil recipes, let’s define what potting soil actually is. The most important thing to understand when it comes to potting soil, is that it doesn’t actually contain real soil. Potting soil – also called potting mix – is a soilless blend of ingredients used to grow plants. Whether you’re starting seeds, rooting cuttings, potting houseplants, or growing in containers and hanging baskets, potting soil is the ideal growing medium for “potted” plants. All good-quality potting mixes have a few common characteristics:

• They drain much better than the average garden soil.
• They are generally lighter weight than garden soil.
• They are easy to handle and consistent.

Unlike most commercial potting soils, you can put together endless combinations of DIY potting soil blends, each with a different texture, nutritional content, density, and water-holding capacity, all fine-tuned to the needs of your plants. Carefully selecting the ingredients you use and combining them in the correct ratios is essential to tailor each DIY potting soil you make to the specific needs of each different plant you’re growing.

For instance:

• Lighter, finer-textured mixes are best for used when starting seeds and rooting cuttings.
• Mixes containing a high percentage of coarse sand or pine bark are best for potted trees and shrubs or acid-loving plants.
• DIY potting soil with a sandy or gravely texture is ideal for cactus and succulent growing.
• When growing a mixture of annuals, perennials, vegetables, and tropicals, the best fit is a general, all-purpose potting mix – one that’s suitable for growing lots of different kinds of plants.

As we said, there are dozens of specialized potting soil mixes you can make.

Main ingredients for DIY potting soil

Most commercial and homemade potting soils consist of a blend of the following ingredients:

Sphagnum peat moss:

The primary ingredient in most potting soils is sphagnum peat moss. This is very stable material, as peat takes a long time to breakdown and is widely available and very inexpensive. It bulks up potting mixes without adding a lot of weight, and once wet, it holds water quite well.

Sphagnum peat moss is well-draining and also well-aerated, but it’s very low in nutrients and it has a slightly acidic pH, typically ranging between 3.5 and 4.5. Limestone is usually added to peat-based potting mixes to help balance their pH. We normally use high-quality, organic bales of peat moss for our potting soil, blended with crushed limestone at a rate of 1/3 cup lime for every 6 gallons of peat moss.

Cocoa coir fiber:

Cocoa coir is a by-product of the coconut industry, and looks and performs a lot like sphagnum peat moss in both commercial and DIY potting soil blends. It has a bit more nutrients than peat moss and lasts much longer, but it’s more expensive to purchase. One of the main characteristics of coir fiber is that it’s pH is close to neutral.

Cocoa coir is often sold in compressed bricks, and is considered by many to be more sustainable than sphagnum peat moss, as it’s mostly a waste product, while sphagnum peat moss requires several years to replenish, making it quite unsustainable to harvest.

Perlite:

Perlite is a mined volcanic rock. When heated it expands, making perlite particles look like small, white balls of Styrofoam. Perlite is an extremely lightweight, sterile addition to commercial and homemade potting mixes.

It holds three to four times its weight in water, increases pore space, and greatly improves drainage while maintaining the soil very light. With a inert pH, perlite is very easy to source at nurseries and garden centers.

Vermiculite:

Vermiculite is another mined mineral that is conditioned by heating until it expands into light particles. Similarly to perlite, vermiculite it’s used to increase the porosity of commercial and DIY potting soil mixes. Additionally, vermiculite also adds calcium and magnesium to the soil, and increases the mix’s water-holding capacity.

Though asbestos contamination used to be a concern with vermiculite, mines are now heavily regulated and frequently tested. Organic bagged vermiculite is for us a must-have in any good DIY potting soil.

Sand:

Coarse sand is used to improve drainage and add weight to potting mixes. Mixes formulated for cacti and other succulents tend to have a high percentage of coarse sand in their composition to ensure ample drainage.

Limestone:

Add pulverized calcite limestone or – even better – dolomitic limestone to peat-based potting soils to counterbalance their pH. We recommend about 1/3 cup for every 6 gallons of peat moss. Limestone minerals are commonly mined from natural deposits and are readily available and very inexpensive.

Fertilizers:

Adding fertilizers to peat-based potting soils is another essential step as these mixes don’t naturally contain enough nutrients to support prolonged plant growth and health. A good DIY potting soil recipe should always include a natural fertilizer, derived from a combination of mined minerals, animal by-products, plant materials, or manures, rather than synthetic or chemical products.

We use a combination of several natural fertilizer sources for our potting mixes. Sometimes adding commercially-made, complete organic granular fertilizer, and other times blending our own fertilizer from cottonseed meal, bone meal, and other ingredients.

Composted wood chips:

Composted wood chips lighten up potting mixes by increasing the pore sizes, and allowing air and water to travel more freely in the mix. They’re slow to breakdown but may rob nitrogen from the soil as they do, so the addition of a small amount of blood meal is important when using composted wood chips as an ingredient in DIY potting soil recipes. We use composted wood chips in potting mixes designed for potted perennials and shrubs. To make your own, get a few buckets of wood chips from a garden center and let them compost for a year outside, turning the pile every few weeks.

Compost:

Containing billions of beneficial microbes, and with superior water-holding capacity and nutrient content than soil, compost is an excellent addition to DIY potting soil mix. Because it plays such an essential role in promoting healthy plant growth, we use it in all of our potting soil recipes. We only avoid using it for seed-starting, as it’s often too heavy for young seedlings to handle.

Good quality, DIY potting soil should be light and fluffy, with a well-blended mixture of ingredients. When dried out, it shouldn’t shrink significantly or pull away from the sides of the container.

How to make DIY potting soil

Mixing your own potting soil blend is pretty easy, and it gives you complete control of one of the most critical steps in the growing process. For any gardener that uses containers instead of directly planting in the soil, a high-quality potting soil mix is a must. Blending your own DIY potting soil allows you to better serve the needs of your different plants. The results will be much more stable and consistent, and you will save a ton of money too!

The following DIY potting soil recipes use a combination of the ingredients we mentioned above. For large volumes of DIY potting soil, use a cement mixer or a spinning compost tumbler. To make smaller quantities, blend the ingredients in a wheelbarrow, mortar mixing tub, or simply a large bucket. Be sure to mix everything thoroughly to ensure consistent results.

Simple DIY potting soil recipes

General DIY potting soil recipe for flowers, leafy plants, and vegetables

6 gallons sphagnum peat moss or coir fiber
4.5 gallons perlite
6 gallons compost
1/4 cup lime (if using peat moss)
1 & 1/2 cup of the DIY fertilizer blend OR 1 & 1/2 cups of any granular, complete, organic fertilizer.

DIY potting soil recipe for trees and shrubs

3 gallons compost
2.5 gallons coarse sand
3 gallons sphagnum peat moss or coir fiber
2.5 gallons composted pine bark
3 gallons perlite
2 TBSP of lime (if using peat moss)
1 cup granular, organic fertilizer (or 1 cup of the DIY container fertilizer blend mentioned above)
1/4 cup organic cottonseed meal, if growing acid-loving trees and shrubs

DIY potting soil recipe for succulents and cacti

3 gallons sphagnum peat moss or coir fiber
1 gallon perlite
1 gallon vermiculite
2 gallons coarse sand
2 TBSP lime (if using peat moss)

DIY potting soil recipe for seed germination

2 gallons sphagnum peat moss or coir fiber
2 gallons vermiculite
1 gallon coarse sand
3 TBSP lime (if using peat moss)

DIY potting soil recipe for seedlings

2 gallons sphagnum peat moss or coir fiber
2 gallons vermiculite
1 gallon finely screened compost
3 TBSP lime (if using peat moss)
2 TBSP granular, organic fertilizer (or 2 TBSP of the DIY container fertilizer blend described above)

DIY potting soil recipe for houseplants

2 gallons sphagnum peat moss or coir fiber
1.5 gallons perlite
2 cups coarse sand
3 TBSP lime (if using peat moss)
2 TBSP granular, organic fertilizer (or 2 TBSP of the DIY container fertilizer blend found above)

Final Thoughts

If you have plants in pots or containers, creating your own DIY potting soil is an essential step to ensure consistent growth, health, and success with your gardening.

When making DIY potting soil, try to use the batch as quickly as possible. But if storage is necessary, place the mix in sealed plastic bags in a cool, dry place.

Even if you are using truly smart plant care systems like KORU, a great soil ensures your plants will thrive and grow.