Help! I Have Fungus Gnats

I’ve been using your organic potting soil for both outdoor and indoor planting for the past 8 months.  Over the past 3 months, my house has been inundated by fungus gnats.  I have tried everything written in the literature to get rid of them.  Yesterday, I ran out of your potting soil and began researching potting soil on the web.  While still recommended, I read that many consumers of your product complain of gnats.  What should I do?  What can you do?  Please help. Question from Marilyn or Colorado

Answer: Every top manufacturer of potting soils get fungus gnat complaints. Fungus gnat infestation and management is a cultural matter and not soil dependent. This is because fungus gnats are everywhere soil, algae, fungus and plant material can be found. Once plants are brought indoors, gnat populations explode because most gardeners don’t understand how to stop them or how they enter the home.

Fungus-Gnat-Free Manufacturing

Black Gold bagged growing media is manufactured at production facilities under conditions unfavorable to the growth and reproduction of fungus gnats, fungi, and algae. Why? Our mix and manufacturing facility conditions include:

  1. The use of high-quality Sphagnum peat moss, which is too dry to be conducive for fungus gnat reproduction and algal/fungal growth
  2. Mix components with low pH levels and nitrogen availability, which prohibit gnat/algal/fungal growth
  3. Mix compost from piles too hot and dry for fungus gnat reproduction and algal/fungal growth
  4. Thick, well-sealed bags to maintain mix integrity

Fungus gnats can enter any opened or damaged bag of potting soil or amendment, so keep opened bags well sealed and dry after opening and never buy any bagged soils with open ends or tears! Once you have these gnats, they are pretty easy to manage, if you know what to do.

Managing Fungus Gnats

All potting soils must contain organic matter, be porous, and hold water well for effective root growth; any soil that’s moist and high in organic matter will attract fungus gnats. But, don’t despair! Follow the simple cultural guidelines in this video, and you can easily stop fungus gnats from breeding in your plant pots.

Happy gardening!

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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