Extending the Harvest

Tomato_DBG_20090915_LAH_0507As fall finally arrives, it’s time to think about early frosts and the end of the growing season. At our house, we are happily celebrating the end of the summer squash glut, and I have no plans to prolong that harvest. Our pole beans are looking a bit peaked, and production has stalled. We enjoyed a bountiful crop, so again, I’m happy to let them succumb to frost.

On the other hand, our tomatoes have just started ripening. (They wilted severely while we were evacuated for the Black Forest fire, and I think it set them back at least a month.) The huge plants are loaded with promising yellow, orange, and pale red fruit, and I’m unwilling to give up so close to our goal.

The chard is also flourishing. This year’s warm and humid summer was just what they prefer. Chard is somewhat frost-hardy, but won’t survive the winter without some help.

We typically experience a few frosty nights followed by another few weeks of warm weather. How can I protect my tomatoes so they can finish ripening on the vine? And is there a way to keep chard coming for weeks after the weather consistently freezes?

When covering plants against frost, the key is to remember that the heat is in the ground. Nighttime air temperatures may plummet, but my garden beds won’t freeze until November. I want covers that will trap that ground heat.

Draping a blanket or old bedspread over my tomato plants is easy and effective. Make sure the bottom of the fabric reaches the soil, and spread it out to form a tent. Just wrapping the stems and leaves won’t help very much. Plastic sheeting can also be used, but try to keep the plastic from touching the leaves—hard to do without some sort of frame. These photos illustrate one idea.

PVC frame covered LAHIt takes something heavy to hold the plastic in place on a windy day. Water-filled milk jugs are one option. Large bricks or pieces of wood also work well.

Make sure to remove opaque covers once the day warms, as the plants need sunlight. Clear plastic is fine if the weather is cloudy, but on a sunny day it will focus the sun’s rays and fry the plants you are trying to save.

Once temperatures are consistently below 60 (either for exposed plants, or in a plastic “greenhouse”) it’s time to acknowledge the end of the tomato growing season. Cool temperatures result in flavorless, watery fruit. You can either pick them to ripen on your counter (light is not required for this), or hang the entire plants in a protected spot, picking the tomatoes as they turn red.

What about chard, lettuce, spinach, and other frost-hardy greens? Nothing needs to be done until the hard freezes arrive. Then, a cover (a portable cold frame, or plastic panels laid over a raised bed) will keep you in fresh leaves. It’s unlikely that the plants will grow new leaves, but you can keep picking the current foliage until it’s either mushy or eaten.

Spinach is particularly cold hardy. Given some protection, fall crops will overwinter, then resume growth in the spring. Be sure to eat these plants before they start to bolt. Cold winter temperatures tell the plant to hurry up and bloom as soon as the weather warms.

CSU Professor David Whiting has his own way of protecting smaller plants from frost. As you can see, he uses concrete reinforcing wire for support, then staples clear plastic over it. One year he even added Christmas lights! The heat they gave off increased the coldframe temperatures by 4 degrees.

CoverSlit David Whiting CSUCovOpen David Whiting CSU

Cole Crops
Other frost-tolerant plants include cabbage and its relatives (cauliflower, kohlrabi, broccoli, etc.). Brussels sprouts and kale taste much sweeter after a frost. If you think you don’t like them, it may be that you’ve never had frost-kissed sprouts. Pick cauliflower and broccoli when a hard freeze is predicted, and store them in your refrigerator.

We can’t hold off winter forever, but a few handy tricks can keep those fresh veggies coming for a bit longer. At least I won’t have to eat zucchini again until next summer!

One thought on “Extending the Harvest

  1. When I wrote this post a week ago, everything was still green. Since then we’ve had one hard freeze, and snow is predicted for tomorrow night. I guess I should have posted this a bit earlier!

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