When to Harvest
Harvesting the Roots: Beets can be harvested at any time in their growth cycle. Greens are best when four to six inches tall. Beet roots are generally most tender after growing for 40 to 50 days. The best size is between 1-1/4 to 2 inches in diameter. As beets get larger, they tend to become more fibrous. When harvested, leave at least one inch of foliage on the root to avoid bleeding during cooking.
We mentioned earlier in the planting section that if you plan well, you could have tiny beet greens quite early in the season if you use those plants that were thinned or removed to give the main crop room to grow. These thinnings are particularly good additions to soups or stir-fries.
Beets taste best when picked soon after maturity. Most gardeners leave them in the ground too long before picking. The flavor of beets fluctuates when the plant is in the heat of summer. Beets taste best when picked in late spring and again in late fall.
Beets can withstand frost and mild freezing but should be harvested before a hard freeze occurs.
If you are harvesting for the roots they don't have to grow to any particular size to be ready to eat. However, they are best small: picked when 1 1/2 to 2 inches in size though some varieties can grow twice that size with little loss of flavor or texture. The texture of the larger beets can become fibrous or woody unless plants are supplied with adequate water during hot weather. You don't have to pick all your beets exactly as they reach harvest size, but the sooner the better. You can pick them for up to 4 to 6 weeks before they become too woody. For the sweetest taste and most tender texture plant a fall crop and plan to harvest the roots after the weather turns cool.
Harvesting the Greens: As the beetroots mature, you can harvest some of the leaves to be used as greens. You must be careful to avoid overdoing a good thing. Excessive removal of the leaves for greens will inhibit enlarging of the root. Harvest greens lightly until beet is ready for harvest at 1-3" in diameter. Young, tender tops are the best quality, but tips of leaves can be used until they get large and strong flavored. Young plants can be cooked with the root and top together, or use the root alone when it is golf ball size or larger.
Beet Greens: Beet greens can be wrapped in plastic and stored for several days in the refrigerator.
Storing Beet roots: Dig the root when the soil is dry so less soil will cling to the roots. They may be washed but should be allowed to dry before being stored. Cut off the tops two inches above the root, and refrigerate beets in plastic bags. They will keep for one to two weeks.
Best Long Term Storage Method: Beets can be stored in damp sand in a cool (32°F to 40°F), humid (95 percent) place such as a root cellar for two to five months. To store roots, first remove beet tops, leaving about a half-inch of stem and don't cut root end to prevent bleeding. If the leaves are not removed, water will travel to them from the roots, and the beets will shrivel. You can store beets through most of the winter by snipping off the greens and laying them in layers of damp sand, sawdust, or peat moss in a plastic container with a tight lid like a garbage can. The tight lid is important to keep the moisture in the sand. Keep the beets and layering in a cool place such as an unheated attic or in an insulated but unheated garage. They will last for two to three months in this condition.
Frozen beets are only fair in quality but will keep for about 8 months. Canned beets will keep for more than 12 months. Beets can be pickled as well.