As it is now December and it’s been a month since I have even seen the grass or anything green in my yard, I wouldn’t normally be thinking about how to kill garden pests. However, I have got the Kratky hydroponics lettuce growing at full speed.
I started the first batch of lettuce well before the end of outdoor gardening season so that I’d have lettuce even after the snow started falling. Becky, the gardening guru, warned me against doing that. She suggested waiting until the outdoor plants were good and dead to avoid having any pests on the plants inside.
But, you know, lettuce. I needed it. And besides, I was starting with brand new rock wool, mesh pots, and seeds. Those things wouldn’t have any bugs or their eggs.
Unfortunately, Becky was right. Again. The first batch of hydroponic lettuce was looking fabulous. I noticed a couple of aphids, but nothing totally alarming. And then two or three days later, total invasion. Stupid bugs.
I harvested all the lettuce and carefully washed the aphids off. Then I put all the hydroponics jugs, rock wool, and mesh pots outside to freeze for a few days with temperatures in the teens. That should kill all the little buggers, right?
I started the lettuce again and had some gorgeous heads forming up. And the aphids appeared again.
Clearly, I was not going to win this battle by freezing them out. I would have to resort to a pesticide. I knew I’d seen recipes for DIY pesticides in the past. I’d even posted a recipe earlier this year for homemade dormant oil spray which will also kill aphids. But that dormant oil spray also contains vegetable oil. You have to be careful applying it outside to make sure you don’t overdo it such that the oil burns the leaves on a sunny day. I wasn’t sure how that would work with grow lights and didn’t want to take the chance if I didn’t have to.
Combine in a spray bottle and spray on affected plants, especially on the underside of the leaves where aphids really like to hang out.
Some sources insist that a mild soap like Dr. Bronner’s is best; others indicate that something like Dawn will be just fine. I went with Dr. Bronner’s because I had it. I’d use Dawn if I didn’t and am pretty sure it would work just as well without harming the lettuce.
I sprayed the lettuce well, including the undersides of the leaves and found that it worked really well.
Now, “everyone” suggests re-applying the spray every few days to keep the aphid population down. But you know what the risk is, right? That some little buggers will have a natural resistance, and then they will multiply into a super-resistant strain of aphids.
The solution, then, is to have a few different insecticidal solutions. Kind of a drag to have to do this, but better than risking playing a leading role in your own personal Invasion of the Super Aphids movie.
Combine all
ingredients in a spray bottle. Apply
liberally to plant leaves and stems, and especially to the underside of the
leaves to kill aphids.
Combine cinnamon and water in a spray bottle. Spray plants, especially the undersides of the leaves, to control aphids and other insects.
All of these aphid killers may be made in larger batches for outdoor use as well.
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