One of the first vegetables harvested in spring, asparagus season is tantalizingly short. All too soon, those sweet, melt-in-your-mouth spears have vanished. Yet unlike other vegetables, they miraculously reappear next spring.
Realizing that it's a true perennial is the key to growing asparagus (Asparagus officinalis): commercial growers usually count on 15 to 20 years of harvest; many home gardeners keep theirs going for 40 years or more. That means you have to be especially picky about where you plant it — usually not in the middle of the vegetable patch. Its deep root system will be a major obstacle when you till the soil in spring. If you're only growing a few plants — two or three asparagus plants are probably sufficient for a family — it's best to grow them at the edge of the vegetable patch, or even in a perennial border. The long, branching, green stems and delicate, cut-leaf foliage form a tall (to 150 centimetres), attractive plant that adds height and volume to the back of the border.
If you want to grow dozens of plants, prepare a special bed just for them — or let them share one with that other perennial vegetable, rhubarb. The bed can be any size or shape you want as long as there's ample room.
Asparagus prefers soil that's been dug down at least 40 centimetres and turned over. Remove any rocks or debris; do a soil test and correct the pH if necessary-soil should be close to neutral (pH 6.5 to 7.5); then work in plenty of compost or well-decomposed manure. Good drainage is crucial: create raised beds if your garden is in a low spot or the soil is clay. Plant in full sun or light shade. Asparagus will shade out other plants, so plant it to the north of its neighbours.
You can grow asparagus from seed or plant young plants, called crowns. Seed is comparatively inexpensive and has a high germination rate — usually well over 100 plants per package. The downside is you'll have to wait for the third spring to harvest. Soak the hard seeds in warm water for 48 hours, then sow four centimetres deep in early spring, indoors or out. Germination is slow and sporadic (anywhere from 10 to 24 days), but usually every seed will sprout. By fall, the seedlings will be large enough to move to their permanent spot. Let them grow a full year in their new home, then start with a light harvesting in year three. Normal harvests begin in year four.
Even though they are more expensive, most gardeners plant crowns, available in garden centres and by mail order, usually in spring. Price is offset by quality — only a few are required and harvesting can begin the following year. Dig individual planting holes or, if planting an asparagus bed, a trench. Plant with the tip of the crown set about 15 centimetres below the ground, then cover with three to five centimetres of soil, gradually filling in the hole or trench as the shoots become taller. Space plants about 30 to 45 centimetres apart, with the same distance between rows.
Although asparagus is generally problem-free, here's what to do if trouble strikes: Crown rot can occur if you're growing asparagus in poorly drained or excessively acidic soil, and the plants rot away at the base. The best long-term solutions are to raise the beds, then correct the pH level every few years. Dispatch aphids or striped or spotted asparagus beetles with a few sprays of insecticidal soap, repeating every three days as needed.