It’s the end of the growing season, and you’ve tossed your spent container tomato plants in the compost. Can you reuse the soil next year? Here’s a soil recycling checklist to go through before repotting plants in old soil or using last year’s soil leftovers in the spring.
Pitfalls of Recycling Soil
Reusing soil is the perfect way for a frugal gardener to save money, but there are some risks involved in potting up new plants with old soil. Here are a few things to keep in mind:
- Diseases may be lurking. Soil may contain diseases like viruses or fungi that can infect newly planted plants. Don’t reuse soil from a pot with a plant that died of or showed signs of disease.
- Food may be scarce. Recycled soil may be deficient in nutrients. Old soil will be depleted of nutrients. You’ll need to cut the soil with fertilizer or compost for the best results.
Soil Recycling Checklist
Here are a few things to keep in mind for your soil recycling checklist:
- Check for diseases or pests. Was the previous plant showing signs of disease such as yellowed leaves, stunted growth, or general poor health? If the last plant that grew in that soil was diseased. Toss out the soil rather than recycle it or try to sterilize it.
- Eliminate weeds. Are there weeds actively growing in the pot or container? Are there weed seeds hidden inside? Pull the weeds, sterilize the soil, or use it for something other than potting soil.
- Fertilize. Old nutrient-depleted soils need to be revived with a fertilizer like compost. Mix some in to boost fertility before recycling the potting soil.
- Do some testing. Get the soil tested to check for pH or nutrient imbalances that can affect nutrient uptake and plant health.
You can also use old soil for things other than potting up or planting new plants. Use soil to patch up holes in your lawn or add bulk to very large containers. You can also mix old soil into your compost.
How to Sterilize Soil
Let it sit in the sun to kill insects, weed seeds, and pathogens. Alternately, you can also use your oven to zap all the nasty things hiding in old soil.
Steph Coelho is a freelance writer gardening in zone 5b. She is a certified Square Foot Gardener and has taught various garden-related workshops. When she’s not digging in the dirt or writing, she’s cooking up fresh produce, running, or listening to her favorite podcasts.