Understanding Harvest Time

It dipped down to 28°F here in Minnesota the other night, so the day before I scrambled to harvest the last of the Sun Gold tomatoes that we’ve enjoyed all summer. I’m telling you, now that I’ve discovered this tasty, hybrid cherry tomato I will definitely plant one every year. And one is all you need because the indeterminate vine grew to nearly 6 feet tall this summer and produced sweet little orange tomatoes from June through, well, two days ago. And if the frost hadn’t hit, it would have just kept right on going.

Sun Gold hybrid cherry tomatoes

As someone who is still learning how to grow many types of vegetables, I know how tricky it can be to figure out the best time to harvest in the fall.  I’ve learned that you can’t rely on the stated days to maturity because that number can be affected by things like temperature, precipitation and the health and fertility of your soil. Instead, I’m learning which vegetables can tolerate frosts and freezes, as well as how to read the clues plants offer us at harvest time.

Generally, tender vegetables like tomatoes, cucumbers, eggplants, snap beans, summer squash and peppers need to be harvested before a frost, which can occur at temps between 32°F and 36°F. But other vegetables like lettuce, spinach chives, carrots and parsnips can tolerate a light frost. Cabbage, broccoli, cauliflower and Brussels sprouts can tolerate quite a bit of frost, but they should be harvested before a hard freeze—24°F or below. I always associate winter squash and pumpkins with very cold temperatures, so I didn’t realize until recently that those actually need to be harvested before frost arrives because frost can damage their rinds and shorten their storage potential.

I’ve learned that Brussels sprouts actually taste better if you let them experience frost, and this is supposedly true of kale, too, though my own totally unscientific testing suggests otherwise. (It seemed the same.) Broccoli should be harvested while florets are still tight. Carrots can take a frost, and I met a farmer the other night who swears carrots taste better after a light frost. Anybody else think that? And I learned by accident, because I missed it in the garden, that Swiss chard weathers a frost just fine. (Which is kind of too bad because I’m honestly a bit tired of eating chard at this point.)

But getting back to tomatoes, I picked mine green and put them in a big bag to ripen. But had I left them on the vine through the frost, I’ve noticed that some experts say it’s just fine to can frosted tomatoes while others say it is unwise because the frost affects the fruits’ pH level, lowering the acidity needed to make them safe for canning. Who’s right here? I would love to hear your thoughts.