University of Vermont Extension
Department of Plant and Soil Science
HARVESTING SUMMER VEGETABLES
Dr. Leonard Perry, Extension Professor
University of Vermont
Knowing when to harvest vegetables is just as important as knowing how
to grow them. Some have a long time over which you can harvest, others
must be harvested at just the proper stage of ripening. Harvest at the
wrong time, and your vegetables may not ripen properly if too young, or
be tough and bitter if too old. You can’t really go by the calendar, or
days to maturity, as this can vary from year to year with such
conditions as rain, temperature, and nutrition. The best way to tell
when to harvest is traits of each vegetable. Here are some specific clues.
Lima beans are best harvested when the pods are full, but before they
start turning yellow. They are more tender when immature, more meaty
when mature. The same applies to snap beans. When the seeds inside are
half size or larger, the pods will be more fibrous and starchy.
There are three traits which indicate a cantaloupe is ready for
harvest—the stem slips easily from the vine, the “netting” on the
surface turns light tan, and the blossom end (opposite the stem) is soft
(push gently with your thumb) and smells sweet.
Feel the tips of sweet corn ears. When they feel full through the husk
they are ready for harvest. You’ll see dry silks. Open the top of the
ear, peeling back the husks, and kernels should be filled out. Press a
kernel with your fingernail, and it should have a milky sap. Use as soon
as possible after harvest for the maximum sweetness.
Length of cucumber when mature will vary with variety, but generally
they are one and one-half to two and a half inches across, and five to
eight inches long. They are best harvested slightly immature when spines
are soft and before the seeds become half sized.
Eggplant maturity and size varies with variety too. In general, harvest
when nearly full size and bright and shiny. When they turn a dull color,
and seeds turn brown, they are overripe.
If you didn’t harvest onions for eating while still small, harvest when
one to one and a half inches across for boiling and pickling. Harvest
them even larger, when tops fall over and the base of leaves (“necks”)
shrivel, for storing and general cooking.
Harvest hot peppers as you need them, the young and green ones being
hotter in many cases than the mature and colored ones. Late in the
season you can pull the whole plant, and dry in a warm, well-ventilated
space. On the other hand, harvest sweet peppers when the fruits are full
and firm. You can leave them on the plant if you want them to turn red.
For new potatoes, harvest only a couple weeks after they bloom. For a
main crop, harvest tubers when the tops have died down later in the
season. Harvest when the soil is dry if possible, and carefully to avoid
bruising. Cure potatoes for about two weeks in a cool (45 to 60 degrees
F), dark, and well-ventilated area. For sweet potatoes, harvest in fall
before frosts and freezes. Handle them carefully to avoid bruising, but
unlike regular potatoes cure for about one week dry and warm (80 to 85
Summer squash should be harvested when young, tender, and a fingernail
easily nicks the surface. Winter squash should be harvested when mature
fruit is hard and can’t be scratched with a fingernail. Harvest winter
squash before the first hard frost, with a sharp knife, and leaving and
inch or so of stem attached. Without a stem, fruit will begin decay from
the scar. Dry winter squash for 10 days to two weeks in a dry, warm area
(75 to 85 degrees F). Harvest and treat pumpkins similar to winter squash.
Proper time to harvest tomatoes varies with variety, but in general is
when the fruit is uniformly red (or colored in the case of yellow or
other varieties) and the end is still firm and not soft. Ripe fruit
should sink when placed in water. If late in the season and frosts are
predicted, you can harvest green tomatoes. They will ripen fine in dark,
and in fact light can delay ripening. Keep them warm (55 to 70 degrees
F) until ripe, and you should be able to store this way for three to
For all your vegetables, regular inspection every few days is the key to
the best and longest harvest season. There are several cool season crops
such as lettuce, carrots, and cabbage that can be planted out in late
summer for fall harvest. More tips on growing these and other vegetable
crops in the North, as well as their storage, can be found in articles
from Cornell Cooperative Extension (www.gardening.cornell.edu).
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