Pests, and where I'll tell you straight I'm still guessing
Last lesson was stretching the fall harvest into November. Today's a different kind of honest.
I need to tell you up front: pests are my weak spot. Everything else in this course, I can hand you numbers, measurements, a thing I built and tested. Pests, I've mostly just lost battles and moved on. So take this lesson as "here's what I've tried" and not "here's the answer." If that's not what you signed up for, fair enough, but I'd rather say that than hand you advice I don't actually trust.
Why covers help more than they hurt
The good news first. Row covers and cold frames do a lot of pest work without you trying. A physical barrier between a cabbage moth and your kale is still a barrier, whether you put it there for frost or not. I've noticed my covered brassicas in fall get way less flea beetle damage than the ones I left open in a spring bed. That's not a controlled experiment, it's just what I've seen. But it's consistent enough that I believe it.
The catch is you have to close the loop. If you're venting during the day (and you should be, we covered that) you're opening a window for whatever's been waiting outside. Aphids especially. They'll ride in on a warm afternoon and set up shop somewhere you won't notice until the leaves start curling.
What actually gets in anyway
Slugs are the big one under cover, honestly. You've made a moist, mild, wind-free environment, and slugs love that environment more than they love the open garden. If you're running a cold frame over lettuce or spinach in fall, check under the leaves in the morning. I use a shallow dish of cheap beer sunk into the soil, it works about as well as anything I've tried, which is to say partially.
Aphids show up on anything under cover for a long stretch, particularly if you're not venting consistently. I've had luck knocking them off with a strong spray of water, and I've had that same fix do nothing the next week. I don't have a clean answer here. I mostly just check the undersides of leaves every time I'm out there, and I pull the worst-hit plants before they spread it to the row.
Mice and voles will absolutely use a cold frame as a warm winter apartment if you let the covers stay closed and undisturbed for weeks. I lost a row of carrots to voles two winters back before I figured out what was happening. Now I do a physical check every week or two even when nothing looks wrong, just lift a corner and look.
The kid factor, because it's real
Lincoln was three when he pulled up half a row of carrot seedlings, convinced he was helping. I came out to check the bed and found this little pile of carrot tops laid out neatly on the path, like he'd done a job well done. I replanted what I could save and let the rest go. That's its own kind of pest, honestly, and there's no cover fabric for it. You either garden with little kids around or you don't garden for about a decade. So I've made peace with a certain percentage of loss that isn't bugs or slugs at all, it's just family.
What I do, in order
- Check under the leaves every time you're out there. Not a separate task, just part of opening or closing the cover.
- Don't let covers sit sealed for more than a week or two without a look underneath. Rodents especially will move in quiet.
- Pull anything badly infested rather than treating it and hoping. I'm not confident enough in home remedies to recommend fighting for a plant that's already lost. Cut losses, protect the row.
- Grow what you'll actually eat, so a partial loss doesn't wreck your season. This is the one real opinion I'll stand behind here: there's no point extending the season on a crop nobody wants, and that goes double when pests take half of it. Put your effort into the spinach and lettuce and carrots your family actually eats. Losing a third of something you value is a shrug. Losing a third of something you grew because it seemed impressive is just annoying.
I don't spray much of anything, mostly because I haven't found a product I trust enough to recommend with a straight face. If you're set on going that route, read the label carefully and follow it exactly, especially anything with a pre-harvest interval. That's not me being cautious for the sake of it, that's just how those products work.
Before next time
Go check under the leaves of whatever's under cover right now, even if nothing looks wrong. That's the whole habit, and it's the best one I've got.