Successful transplantation of beets from the grocery store often is a matter of timing. Beets are a cool-weather vegetable, so they will grow best during the spring and fall months. Purchase beets individually or in bunches, and select small caliber ones that are approximately 1/4 to 1 inch in diameter for replanting. The greens still should be attached. Clip the leaves off, leaving about 2 inches of greenery. Clip the tiny taproot off, then plant in the ground or in a pot. Soils should come to the top of the beet yet not touch the foliage. This method may work only if beet roots are planted at the beginning of their normal optimal growth period.
No matter how big the beet is, parts of it may be transplanted in water for fresh greens. These parts are not used normally in cooking and will allow for a number of subsequent harvests of the greens. Cut the tops off the beet, leaving about 1/2 inch of the beet's root. Place the cut side down in a dish of water and place in a sunny location in the house. The leaves will continue to grow, and you can harvest these greens and use them much as you might use chard.
Beets purchased at the grocery store may be planted in fall and transplanted in the ground to overwinter. After planting the beets, cover the roots with mulch, but leave the greens exposed. When winter hits and temperatures drop in the colder regions, bury plants under about a foot of mulch. You can harvest the beets as needed over the winter or allow them to grow in spring to set seed. Otherwise, beets purchased in fall or winter can be stored in a cool place and planted the following spring.
Because beets are biennials, they concentrate their energy on vegetative growth the first year and seed growth the second year. When beets are purchased at the grocery store, they are in their first year of growth. Purchase beets in fall and store or plant them. However, the beets that survive may put their energy into seed growth rather than root growth. If so, allow seeds to develop until they're dry, then rub the seeds of the stalk. Beet roots should not be harvested after seed production begins, and greens are likely to taste bitter. Store seeds in a cool dry place. Beet seeds may last up to 5 years.