Avid container gardeners are acutely aware of two facts: potting soil becomes depleted over time, and continually replacing it gets expensive. Old potting soil lacks nutrients, is not properly aerated and can cause drainage problems for plants, ultimately forming a brick of dirt that harms plants rather than helps them. Fortunately, rejuvenating old potting soil is easy and inexpensive and gives you an excuse to go outside and play in the dirt.
Place the potting soil on a large tarp, and use a garden rake to break up any clumps. Remove any rocks, root pieces or other debris that is present in the soil.
Scoop the soil into a large bucket with holes in the bottom. Fill the bucket with water, and allow it to drain out the bottom. Do this twice, and then spread the soil back out onto the tarp and allow it to dry.
Sift store-brought compost through a 1/2-inch screen, and mix it with the soil you are rejuvenating. Add as much compost as you have depleted potting soil so that you have a 50/50 mix of old potting soil and new compost when you are finished. For an alternative that makes a bit less soil, mix perlite and screened compost into the depleted soil, adding 1/4 pound of each for each pound of depleted potting soil. You can transfer the soil into a large bucket or wheelbarrow if you find it easier to mix the soil in a container rather than on the tarp.
Mix in a light dusting of lime and gypsum and 1 tablespoon of slow-release fertilizer for every gallon of soil you have.
Moisten the soil mix lightly, and shovel it into a large plastic storage bin. Allow it to cure in the bin for two weeks before using.
Things You Will Need
- Large tarp
- Garden rake
- Large bucket with holes in the bottom
- 1/2-inch screen
- Store-bought compost
- Perlite (optional)
- Wheelbarrow (optional)
- Lime (optional)
- Slow-release fertilizer
- Large plastic storage tub
- Seal any used potting soil that has hosted insects, diseases or fungal infections in a plastic bag and discard it. Diseases and insects can sustain themselves in potting soil for a long time, and it is best to simply start with new soil rather than try to fix soil with these problems.
- Avoid using homemade compost unless you are a very experienced composter and gardener. Homemade compost often harbors diseases and weed seeds.
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