Asparagus is a member of the lily (Liliaceae) family and a distant relative of the leek and onion. The edible parts of this plant are the tender shoots that are harvested before they produce leafy branches. There are various types of ornamental asparagus, such as smilax asparagus (A. asparagoides), sprenger asparagus (A. densiflorus 'sprengeri'), sickle-thorn asparagus (A. falcatus) and fern asparagus (A. setaceus), grown for their interesting ‘leafy’ foliage. What appear to be green, photosynthetic leaves are actually cladodes (leaf-like stems) or cladophylls (leaf-like branches) that appear as flattened, modified branchlets that develop in the axils (part of a leaf that is deep and can hold water)of the scale-like leaves. Asparagus stems are rich in the amino acids asparagine, tyrosone and arginine, plus succinic acid and a methylsulfonium derivative of methionine. This combination of ingredients (particularly the latter compound) accounts for the distinctive odor of urine shortly after consuming a mass of the stems. According to R.H. White (Science 189: 810, 1975), the malodorous agents in the urine are two sulfur-bearing mercaptans, S-methylthioacrylate and S-methyl 3-(methylthio) thiopropionate. Foul smelling, sulfur-bearing mercaptans are also responsible for the defence mechanism in skunks and the odor of garlic.
Asparagus comes from the eastern Mediterranean area. Archeologists found traces of wild varieties in Africa. Asparagus may also have been cultivated in Egypt. In ancient Greece asparagus was believed to have sacred and aphrodisiac powers.

GENERAL: Asparagus is a high yielding plant that is relatively easy to grow. It produces multiple spears that require regular picking to encourage growth.
One planting of asparagus can last up to 15 years. The plants don't mind drying out a little but it is best to have a good supply of water. Harvesting starts in September (Southern Hemisphere).
GREEN AND WHITE ASPARAGUS: Green asparagus grows freely in flat beds, and exposed to the sunlight, develops the chlorophyll that turns it green. White asparagus is grown covered in mounds of sandy soil so that it never sees the light of day until the moment it is cut. Lacking chlorophyll, white asparagus has a milder taste than the heartier green version.
NUTRITIONAL VALUES: Asparagus is a excellent source of folic acid (vitamin B9) and contains potassium, copper, iron and phosphor. It is rich in insoluble dietary fiber and vitamins A, B1, B2, B6 and C. Asparagus also contains asparagine, an acid agent responsible for its particular flavor and diuretic property. People with kidney inflammation should avoid eating asparagus.
SOIL: Asparagus plants are heavy feeders and like rich soil such as well-prepared deep, well-drained sandy loam. Heavy (clay) soils need to be improved with compost and gypsum. Asparagus is a deep rooted plant and needs the deep soil to grow well. It is important to remove weeds regularly, especially during the growing season as they compete with moisture and nutrients. Full sun is best. In winter the dry and yellow fern leaves should be removed. A light feed of compost in late winter will encourage good growth in spring.
PLANTING: Best to plant in late winter or early spring. Place a small amount of cow pat into a 12 cm deep hole. Backfill gently. Green asparagus is cut from level ground beds when the spears are 15 - 20 cm long. When planting white (blanched) asparagus, make a mound over the rows to a depth of 25 - 30 cm in late winter and as the tips of the spears break through the soil surface, push a sharp knife through the ground to cut the spear about 15 cm below. The mounds can be leveled when the fern growth is cut off in the winter.
HARVESTING: The plant should be at least one year old before harvesting can begin. In the second year asparagus can be harvested for a 2 - 3 week period. The cutting season will increase with every year of age.
Cutting season should end in December (this depends on growing conditions). As the plant draws energy from reserves stored on the root system from the previous season, it needs to restore energy for the next season. Over harvesting will stress the pant and reduce next season's yield. Under very favorable conditions, daily cuttings may be required, but every second day is usually sufficient. The shoots should be cut when they reach a height of approximately 5 cm (6 in.). They should be cut just below ground level. Special care should be taken not to damage new shoots still underground. The growth takes place near the tip of the shoot. Injuring this tip, even while it is below the soil surface, will usually stop the growth of the shoot. Cutting is best done with a sharp knife that is pushed into the ground so that it severs the spear about 2 ½ cm (1 in.) below ground. Freshly picked spears will keep for several days in the crisper tray of a fridge.