I sterilize my used potting soil by covering the pot containing the soil with a black plastic bag and leaving it out in the sun all summer. The temperature of the soil will reach about 150 deg. F on a sunny day. Here in south Florida the growing season is in the fall, winter, and spring, but in other places you could use the soil that you solarized one summer during the next growing season.
I sterilize my used potting soil by covering the pot containing the soil with a black plastic bag and leaving it out in the sun all summer. The temperature of the soil will reach about 150 deg. F on a sunny day. Here in south Florida the growing season is in the fall, winter, and spring, but in other places you could use the soil that you solarized one summer during the next growing season.