Garden Myth: Exposing Tomato Fruits to Sun Helps Maturation

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Even tomatoes completely hidden by foliage ripen. Photo: http://www.denverpost.com

At the end of the summer, my father always stripped the upper leaves off his tomato plants so the fruits would mature more quickly. After all, he reasoned, exposing fruits to the sun makes them ripen, so getting rid of the leaves shading his tomatoes ought to ensure an earlier harvest and less risk of them being destroyed by frost.

And he wasn’t alone in this belief: it was common practice 60 years ago.

I thought this was one garden myth that had mostly died out, as I wasn’t seeing it much anymore, but, judging from the questions about the technique I’ve been receiving lately, it seems to be on its way back in. Maybe this article can help nip that in the bud.

What Makes Tomatoes Ripen

Tomatoes ripen when they are ready to mature, period. You can’t do much about it. Some varieties mature faster than others: it’s built into their genes. More sun (on the leaves) also gives faster maturation; tomato plants in partial shade produce less and their fruits are slower to mature. The weather is another factor, of course. Tomatoes do ripen most quickly at warm but not hot temperatures, but what can you do about that? And yes, keeping them evenly watered helps too. Drought-stressed tomatoes are a bit slower to mature. Adding extra fertilizer is likewise a waste of time. Unless the plant is suffering from a mineral deficiency, it won’t speed up ripening per se.

So, besides providing the best possible conditions for your tomatoes, there’s not much you can do to speed up maturation.

Unless leaf pruning can help?

A Simple Test

Tomatoes ripen just as readily in the darkness of a paper bag as in the sun. Photo: anoregoncottage.com

It’s easy enough to prove that exposure to sunlight doesn’t help tomatoes ripen. Just harvest two tomatoes that still green, but near maturity. Place one in a brown paper bag, perhaps putting it in the pantry to be sure it’s really in the dark, and leave the other exposed, setting it on a sunny windowsill. You’ll see that both mature at the same time and yet the one kept in the paper bag received absolutely no sunlight.

So, it’s pretty clear no sun actually has to touch the fruit for it to mature.

Sunscald and Insipid Taste

The worst part of this myth is that not only stripping tomato plants of their leaves doesn’t help the fruit mature, it can be downright harmful.

Sunscald on a ripening tomato. Photo: MAPAQ

Fruits that were completely shaded by leaves, then suddenly exposed to full sun, may actually suffer sunscald (the plant equivalent of sunburn). They’ll still be edible, but won’t be as presentable. And you have to cut away the damaged part, so they give you less fruit to eat.

Also, foliage, because it captures the sun’s energy and converts it into sugar, gives tomatoes their sweet taste: if you strip off the plant’s leaves, the tomatoes that are forming won’t be quite as tasty! And the plants won’t be as prolific. The more leaves a tomato plant has, the more fruits it can produce.

Of course, you can remove yellow, brown or diseased leaves (that’s another situation entirely), but leave green leaves intact if you want the tastiest, most perfect tomatoes in town!

Article adapted from one published on August 21, 2015.

5 thoughts on “Garden Myth: Exposing Tomato Fruits to Sun Helps Maturation

  1. Margaret

    Thanks so much!

    My mother took so many leaves from tomato plants that my neighbor said that my plants were “bleeding”. Her tomatoes never had that sweet earthy taste we crave. I always thought that she knew what she was doing because she grew up on a farm. Guess farmers’ daughters sometimes make mistakes!

  2. Susan Gilmour

    How about laying the plant on the ground in the late of the year to capture the heat of the ground to help them ripen, myth or not?

    • That would probably work to a certain degree, but at that point in the season, you’re not going to gain that much. I’d be concerned that you’d end up breaking stems rather than just bending them and thus doing damage. Assuming that you have a few cool days ahead, but know a long stretch of hotter weather is going to follow, you’d probably get better results just by covering your plants with an old sheet at night.

  3. The last green tomatoes that are left as the foliage succumbs to frost ripen faster in the kitchen because of the warmth. I put them on the windowsill because it was warm.

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