Happy Valentine’s Day!   My amaryllis are doing their jobs and blooming their hearts out for the occasion.   So are my African violets.

We are going to talk today about a not so beautiful thing, though.

You’ve selected the perfect potting soil, brought it home and now you are ready to plant.  Maybe.

Have you ever been sitting in your recliner, reveling in the nice, healthy plants that surround you and all of a sudden there is this little black speck zipping around your nose, your ears, your eyes?  I know you know what I mean because anyone who has ever had houseplants has had a fungus gnat buzz their face.

I have found that more and more often, shortly after I’ve brought a new bag of potting mix home and transplanted some of my plants, I’ll end up with an infestation of those pesky little buggers.  Fungus gnat larvae get into the soil and feast on algae, fungi, and organic matter in the potting mix.  The adult gnats do not eat on the plant or bite humans or animals.  They exist solely to lay more eggs so that more fungus gnats can buzz around your nose. 

The eggs require moisture to hatch so one of the ways to control them is to allow the potting mix to dry completely before using it.  But, then we talked yesterday about what happens when peat moss dries out completely.  So, it ends up being which will be the lesser of two evils for you – dry peat moss or fungus gnats?  (Here’s a hint – simply drying out isn’t guaranteed to kill all the fungus gnat larvae).

So, what’s a gardener to do?  You can sterilize your potting mix.  If you make your own, you need to do this anyway, and while it’s a little messy, it doesn’t take much effort to do it with store-bought mixes.  Sterilizing can be done outside in a full sun area.  You spread your mixture evenly over a tarp or other porous material, let it set in the sun for four weeks, turn it over and let it set another four weeks before use. 

Now, I don’t know about you, but I don’t plan most of my transplanting eight weeks in advance.  Furthermore, I don’t do it only in the summer when the sun is actually hot enough to kill any bacteria or larvae.  So, I use my oven for small batches.  I spread the potting soil on an old cookie sheet or cake pan and bake it at 200 degrees for 30 minutes; stir it; then return it to the oven for another 30 minutes.  Let cool and plant. 

This will give you a nice, earthy aroma in your house.  So, if “nice, earthy” equates to “stinky” for you, you’ll want to do it on a day when you can open the windows and run your exhaust fan.  Personally, I love the smell in Spring when the soil is coming back to life after a long, dormant Winter and the baking potting soil reminds me of that. 

I don't recommend that you use your oven to sterilize potting soil that contains fertilizer or moisture control crystals.

If you’ve already planted your containers when the fungus gnats emerge, they are harder to control.  You can try letting your container get a little bit on the dry side, consistently.  You can try spreading a thin layer of pure sand over the top surface of the potting mix in your container so that at least the surface dries more quickly.  You can try houseplant insecticides.  And you can swat at fungus gnats buzzing your face.