Composted wood chips lighten up potting mixes by increasing the pore sizes, and allowing air and water to travel 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 or alfalfa meal is necessary when using composted wood chips as an ingredient in DIY potting soil recipes. Use composted wood chips in potting mixes designed for potted perennials and shrubs. To make your own, get a load of wood chips from an arborist and let them compost for a year, turning the pile every few weeks.
Compost:
Containing billions of beneficial microbes, and with superior water-holding capacity and nutrient content, compost is an excellent addition to DIY potting soil. Because it plays such a huge role in promoting healthy plant growth, I use it in all of my general homemade potting soil recipes. But, I don’t include it in recipes for seed-starting as it’s too heavy for young seedlings. I use leaf compost from a local landscape supply yard, but bagged compost from Dr. Earth Compost or Coast of Maine are other favorites.
Good quality, DIY potting soil should be light and fluffy, with a well-blended mixture of ingredients. When it’s dried out, it does not shrink significantly or pull away from the sides of the container.
How to make your own homemade potting soil
Mixing your own potting soil blend is easy, and it means you have complete control of one of the most critical steps in the growing process. For container gardeners, a high-quality potting soil is a must. Making your own potting soil allows you to better cater to the needs of your plants. The results are more stable and consistent, and you save a ton of money.
The following DIY potting soil recipes use a combination of the ingredients I listed above. Mix large volumes of homemade potting soil in a cement mixer or a spinning compost tumbler. To make smaller quantities, blend the ingredients in a wheelbarrow, mortar mixing tub, or a large bucket. Be sure to mix everything thoroughly to ensure a consistent result.
6 DIY potting soil recipes
General potting soil recipe for flowers, tropicals, 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 container fertilizer blend found below OR 1 & 1/2 cups of any granular, complete, organic fertilizer.
DIY container fertilizer blend:
Mix together
2 cups rock phosphate
2 cups greensand
½ cup bone meal
¼ cup kelp meal
Potting soil recipe for potted 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 found above)
1/4 cup organic cottonseed meal, if growing acid-loving trees and shrubs
Potting soil recipe for succulents and cactus
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)
Potting soil recipe for seed starting
2 gallons sphagnum peat moss or coir fiber
2 gallons vermiculite
1 gallon coarse sand
3 TBSP lime (if using peat moss)
Homemade potting soil for transplanting 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 found above)
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)
When making DIY potting soil, use the batch as quickly as possible. But if storage is necessary, place the mix in sealed plastic bags in a cool, dry place.
