Is it Safe To Reuse Soil for Seed Starting?

“Is it safe to re-use Black Gold for starting seeds, etc.? Do I need to sterilize it the following year before planting? I had several flats of seeds with low germination or die-off last Spring and would like to use the soil again. Thanks.” Question from Piper of Petersham, Massachusetts

Answer: It is always safer to start with fresh Black Gold Seedling Mix. This will ensure the mix is ready for growing and pest and disease free. Always choose a bag that’s closed at the ends and has no holes, to make sure the mix inside is fresh. the

Old mix can, however, be sterilized for reuse. It will not be as fresh, but the sterilization process will ensure it is pest and disease free. In fact, I sometimes sterilize fresh seedling mix when I am starting prized seeds. To sterilize mix, I place it in a large, oven-safe pan, add some water to moisten the mix, and then cover it with aluminum foil. Then I bake it at 180-200 degrees Fahrenheit for at least 30 minutes. The soil’s internal temperature should be at least 180 degrees F for sterilization. Allow the mix to cool before use.

Happy seed starting!

Jessie Keith

Black Gold Horticulturist


Plants are the lens Jessie views the world through because they’re all-sustaining. (“They feed, clothe, house and heal us. They produce the air we breathe and even make us smell pretty.”) She’s a garden writer and photographer with degrees in both horticulture and plant biology from Purdue and Michigan State Universities. Her degrees were bolstered by internships at Longwood Gardens and the American Horticultural Society. She has since worked for many horticultural institutions and companies and now manages communications for Sun Gro Horticulture, the parent company of Black Gold. Her joy is sharing all things green and lovely with her two daughters.

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