Timely harvest of vegetables sown or planted outside early in the growing season, and ones that generally mature rapidly or during cooler temperatures results in the best flavor and longest harvest period. Many of these also make good fall crops, started later in the season.
Snap asparagus spears off at ground level when they are six to ten inches tall. Harvest over a period of six to eight weeks, as long as they are pencil thin.
If you planted beets in spring, July may be too late to harvest. Begin harvest when beets reach one inch in diameter, with the main harvest when beets are two to three inches across. Young beet greens are great harvested and cooked too. Harvest fall beets before a moderate freeze (24 to 28 degrees F), or mulch heavily for continued harvest through fall.
Cool crops are ones that you started outdoors during the cool of spring, and that like cool temperatures to grow well. They also can be planted in late summer for a fall crop. Harvest broccoli before flowers start to open, while the individual flower parts (florets) are still tight and dark green. Harvest cabbage when heads are solid. If you wait too long, heads may split. To help prevent this, and to delay harvest, a trick is to pull up on the head until you hear the upper roots snap. When cauliflower heads (curds) are two inches across, tie outer leaves above the head with rubber bands to keep them white. You can then harvest in a couple weeks when heads are larger.
Begin harvest of carrots when they are one to two inches thick. Refer to packet or catalog information for your specific varieties. Harvesting also can be used to thin carrots so some can grow larger. Harvest spring-sown carrots before the heat of July, and late-season carrots before the ground freezes in late fall.
You can harvest leaf lettuce as soon as leaves get to the size you want. Harvest only outer leaves, letting more grow from the inside. Regular picking of leaves extends the harvest season, as does sowing successive crops two to three weeks apart. Spinach can be harvested similarly, or you can harvest the whole plant. Once days get longer than 14 hours, or in heat, spinach will grow tall and bloom—called “bolting”. For this reason, it is often grown in the fall, as well as it being able to tolerate temperatures in the teens to low 20s.
For green onions, harvest when they get to the size you desire. For dry onions, harvest them when they are between one-quarter and one inch across for table use (eating).
When garden pea pods are light green and full, but before they yellow, is the best time to harvest. On the other hand, harvest snow peas when the seeds start to show in pods but before they fill out.
Harvest radishes when they are one-half to one inch across. Finish harvest before the heat of July, or for fall crops before the ground freezes in late fall.
Only harvest stalks of rhubarb, not leaves, as the leaves contain oxalic acid which can be toxic. Pick when stalks are one-half to one inch in diameter.
As soon as turnips reach one inch across you can begin their harvest. They, too, are a good fall crop and will withstand several light freezes, as can kale. Frost, in fact, improves the flavor of both. If left too long, or grown poorly, turnip stems may become woody. Harvest kale when leaves are the size of your hand.
Dr. Leonard Perry, Horticulture Professor Emeritus
University of Vermont
Distribution of this release is made possible by University of Vermont and Green Works—the Vermont Nursery and Landscape Association.