Botanically speaking, many of the plants we refer to as vegetables are fruits. Classifications for vegetables are made by the part of the plant that is eaten. These include leafy vegetables, sprouts, stemmed vegetables, bulbs, roots and tubers. Some of the vegetables that fall under these classifications are asparagus, beets, broccoli, cabbage, carrots, chives, leeks, lettuce, onions, spinach and rhubarb, which is mistakenly referred to as a fruit.
Asparagus (Asparagus officinalis)
Red berries growing from the female asparagus plants contain the seeds. Each berry contains one to eight round black seeds. Asparagus seeds can be planted at a depth of ¾ to 1 inch and two inches apart when soil temperatures reach 60° Fahrenheit. Prior to planting, the seeds should be treated with a fungicide. Thoroughly dried seeds can be stored in an envelope for a maximum of five years.
Cabbage (Brassica oleracea)
Cabbage is a biennial; therefore, it does not produce seeds until the second year of its life cycle. Cabbage sends up a seed stalk that can reach heights of three to six feet. After pollination of the flowers, pods will appear on the stalk. Each pod contains 10 to 30 tiny round reddish brown to black seeds, averaging in size from 0.08 to 0.12 inches. Harvesting of the pods is from the bottom of the stalk up. Seeds stored in airtight jars in the refrigerator or freezer will keep for five years.
Carrots (Daucus carota)
Carrots are also biennials that do not produce seeds the first year of their growth. If left in the ground over the winter, the plant will re-sprout in the spring and produce flowers or umbrels that are two to four feet tall. Tiny tan or black seeds will appear on the primary and secondary umbrels. It takes almost 3,000 carrot seeds to fill a teaspoon, so sowing is a challenge. Seeds should be planted ½ inch deep and spaced every 3 to 4 inches. Carrot seeds can be sprinkled in rows and then thinned out after they have started to grow. This slow germinator prefers soil temperatures of at least 60° Fahrenheit. Interplant carrot seeds with fast growing radishes to indicate row location.
Lettuce (Lactuca sativa)
Exposure to warm temperatures will cause lettuce to go to seed. Seed stalks emerge more easily from leaf lettuce than from head lettuce, where the tight head formation can trap the stalks. The flower heads evolve into puffballs that look similar to those of a dandelion. Seeds attached to the puffballs are 0.16 to 0.20 inches in diameter and cream to black in color. Plant lettuce seeds at a depth of ½ inch with a spacing of two to three inches apart. Seed germination can occur at soil temperatures as low as 35° Fahrenheit. Lettuce seeds stored at low humidity in an airtight jar can be kept for four to five years.
Onions (Allium cepa)
The wrinkled, black seeds of the onion have a dull, greasy appearance and are a mere 0.12 to 0.14 inches in length. Sown at depths of ½ to 1 inches, these biennials prefer soil temperatures of 60° Fahrenheit to germinate. Much like carrots, onions will re-sprout in the spring and send up umbrels that contain the seeds. Onion seeds must be stored at low temperatures with low humidity in order to maintain viability.