The other day, my friend Dave Dewitt who’s a farmer in Truro mentioned something about growing fruits and vegetables that I hadn’t really considered. We were talking about cucumbers — I’ve had a really productive season and I was trying to figure out why — and he mentioned that how frequently you pick from your plants can impact how many fruits they make.
"So all plants have one purpose and that’s to reproduce the species. So a plant will keep producing flowers until it starts to really set seeds in its fruit," explained Dave.
Intuitively, this makes sense. Of course, there’s a step between a cucumber flower and a cucumber seed, which is the fruit we want to eat. With greens, I routinely cut the flowers off my kale and basil and arugula so that they’ll keep growing new leaves, but with something like a cucumber, I’d never thought of trying to manage this cycle, because you can’t just pinch or cut off the flowers — or you won’t get anything. The key, Dave says, is to keep catching the plant after its set fruit but before the seeds are mature. It’s a balancing act.
"So if you let a fruit get large it’s going to go, start to mature seeds and it will trigger hormones and enzymes in the plant that will then stop flower production and slow down flower production and put the energy toward growing the seed so it can reproduce."
Reproduction in any species is all about timing and hormones, and plants are no different. The hormones that trigger something like a cucumber to stop flowering are kind of like the plant version of the hormonal trigger that happens when a hen goes broody — she stops thinking about laying new eggs and starts sitting on the nest, to try to hatch the ones she’s already laid. The difference is, humans have a key role to play in the plant version of this process. We can allow it to speed up or we can slow it down by harvesting.
"So if we constantly harvest before the seed really gets set, then that’ll continue flowering because the plant just wants to reproduce so it's going to keep throwing out more flowers so the same with a lot of your plants are the same way."
I asked Dave to give other examples. I’m thinking about the whole garden, like what you look for in a tomato or a green bean, or a squash, or a cucumber like oh, I’m going to catch this before it triggers that like, oh, we’ve done our job.
"Well, the squash family is important. If you let the zucchinis and the summer squashes and things get too much, then they’ll really slow down its production," he said.
And you’ll have a giant zucchini!
Dave agreed. You'd have "baseball bat-size zucchini," he said.
He went on to say, "family is probably one of the more important ones. Eggplant to some degree can do that, if it really gets set and starts to produce seed, which is a later part of its season, then it will slow down its production for the fall. Tomatoes you have to let ripen, so it is what it is."
Dave says regular harvests are also important with string beans and edamame and that beyond these hormonal triggers, there are a whole host of other reasons to harvest regularly. With many crops, regular picking also reduces the spread of disease — for instance I’ve noticed that if I don’t pick fruits like mulberries and strawberries and blueberries at least every other day, molds and fruit flies start to show up on the overripe fruit, and then these spread disease.
Talking with Dave was a good reminder that while so often we think of yield as predetermined by factors outside of us like the weather, or the soil, or the genetics of the plants we’re growing — this isn’t the whole story. Gardening is an interaction between species, a relationship that’s evolved over millennia to include us, and often, we’re shaping the process more than we think.
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