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Tuning into plant flowers to manage fruit and vegetable productivity

Over the past few years, I’ve started noticing how much I can control certain plants’ productivity by managing their flowers and seeds. With arugula, for instance, if I keep cutting off the flowers and greens back to the ground, I can extend the season for weeks. Farmer Stephanie Rein of Truro says tuning into cues like this is the key to managing all food crops.

"You know the goal of most plants, pretty much all of them, is to reproduce. That’s their main goal. So when I look at a plant, I want to think about what part I want: to have, to consume, to sell. And then you manage its lifecycle to the outcome that you want."

On the surface, this sounds pretty basic. And it can be. For instance, with most greens, as with my arugula, the goal is to prevent the plant from flowering.

"Think about a kale plant, or basil. You want the big leaves," explains Stephanie.

She added, "And it sends up like a stalky flower with like little white blossoms on it. And you want to lop that off throughout the summer because you want all the energy to go to the leaves. And if the flower comes to fruition and makes seed, it stops really making leaves."

Basically, the plant has achieved its goal — reproduction — and since it’s just an annual, meaning it only lives one season, once it does this, it’s no longer going to produce the food we want to eat. With greens, this is called bolting and is easy to see and manage. But with other crops — particularly those where the part we want to eat is underground — it’s easy to forget that a similar process is taking place.

"So garlic is, obviously a root crop and it's underground and you want all the energy to go into the bulb."

This is why many gardeners cut off garlic scapes — the twisty little green stalks with white flowers at the tip that emerge in early summer.

"And if it opens up its flower, the energy is going to its seed. Potatoes are the same thing. Great crop. I grow a ton of them and they have a lovely little flower. And if you actually let it go all the way through its cycle, you'll end up with little tiny potatoes like a bouquet of tiny potato balls."

This is one I’d never thought about before. I don’t cut the flowers off my potatoes, and that’s probably why I’ve never had a particularly impressive crop. But it makes sense — anytime you want the root of a crop, you want to either cut off the flowers or harvest the roots before the plant can go to seed, so that the part you want — the carrot or the turnip or the potato — stays big and tasty. But before you start believing cutting off flower is the rule — remember that this is actually the opposite of what you want to do with plants where the part you want to eat is a fruit.

"Whereas say a tomato or a squash, the fruit comes out of the flower. So you need those flowers."

Obviously, if you cut off a few squash flowers to stuff and fry you’re not going to kill the plant, but in general, with any plant where you’re trying to harvest fruit, more flowers means more food. With one small exception.

"When you're growing any of the squashes, be it a pumpkin, we grew giant pumpkins for a while, and we learned this," she said.

"You always cut off the first two fruits. So when that tiny little cucumber, say, first emerges. And I used to be so excited. Look, I finally have cucumbers at the beginning of the season. There's something that if you cut off the first two, it will be a more prolific plant. And it goes back to sort of the discussion we're having that very first, fruit, be it a cucumber, an acorn squash, a pumpkin, a lot of the energy is going into producing that. And so by cutting off the first two, you're sending the energy back into the plant. And in the end, you'll have a much larger yield from a cucumber. That's the same with, watermelons, all of the cucurbit family."

Some gardeners also say you should pinch off the flowers on an eggplant or tomato if the plant starts blooming when it’s still in a pot or really small — because you want it to get established and send energy to the roots first. And Stephanie says that with most plants, it’s also important not to let ripe fruit sit too long.

"Blueberries too, you know, the more you pick those, and raspberries — same thing. A raspberry, you can have them for, you know, months. But you've got to keep picking if you leave them and the fruit, you know, dries on the vine, then it's done its job and its party's over."

I’ve noticed this with my mulberry tree. The more I pick, the more it makes. Which sounds like kind of a paradox, but is actually how the wonder and bounty of the plant world works.

An avid locavore, Elspeth lives in Wellfleet and writes a blog about food. Elspeth is constantly exploring the Cape, Islands, and South Coast and all our farmer's markets to find out what's good, what's growing and what to do with it. Her Local Food Report airs Thursdays at 8:30 on Morning Edition and 5:45pm on All Things Considered, as well as Saturday mornings at 9:30.