By John Chwistek, U. C. Master Gardener

Asparagus

Asparagus and artichokes grow best when temperatures are between 55ºF and 75ºF. Mature plants will tolerate some frost.

They can both be grown from seed, however they are more efficiently grown from plants or roots. You can plant asparagus and artichoke crowns from October through January. Artichokes can also be planted in February and asparagus seedlings may be planted in February and September.

To plant asparagus, first dig trenches eight to ten inches deep and one foot wide, spacing trenches four to six feet apart. Break up the soil in the bottom of the trench to a depth of ten inches, and mix in compost, well-aged manure and a complete organic fertilizer. Carefully spread each root back into a circle and lay it in the trench, crown up.

Space the crowns one foot apart, and cover the roots with one inch of soil. As the plants grow, gradually fill in the trench with soil. Do not cover the top of the plant. Keep adding soil, no more than two to three inches at a time, during the growing season until the trench is filled.

Keeping the beds weeded and deeply irrigated during the growing season. The all-male varieties 'UC 152,' 'Jersey Giant' and 'Jersey Knight' produce more and larger spears because they don't have to put energy into seed production. These varieties may produce an occasional female plant.

Do not harvest asparagus during the first year. Let the plants develop a large root system. During the second year, harvest the spears for only one week, and take no more than two or three spears per plant.

From the third year on, harvest spears that are no more than 3/8 inch in diameter and six to eight inches tall. Let the thinner spears grow into ferns. Cut the spears at or just below the soil. Stop harvesting when most of the emerging spears are small and the tips become loose and open. When harvest ends, fertilize the bed with a complete fertilizer. When the tops turn brown, cut them down.

Plant artichoke root shanks vertically, with new buds or shoots just above the soil level. Mature plants are large, so space four to six feet apart. When growth starts, water the entire root system once a week and fertilize once a month during the growing season.

Harvest the chokes when the buds are firm and tight and have a nice green color. The top bud is the first to mature, followed over the next few days by lateral buds. To encourage a second growth, cut off the main stalk an inch above the ground after harvesting the last bud of the first crop. New shoots will appear, and a smaller and more tender crop will follow. Remove yellowing leaves and cut old stalks to ground level.

Artichokes are susceptible to aphids. Use strong jets of water to displace the insects, and bait for snails and slugs. If you don't harvest the buds, they will open to form five- to six-inch-wide periwinkle-blue flowers that resemble proteas. Floral designers treasure these dramatic blooms, so besides being delicious, artichokes make striking ornamental plants as well.