Because of its open growth habit, weeds are asparagus's worst enemy. Since plants are easily damaged by hoeing, hand weeding is best. To control weeds, mulch plants to a depth of eight to 10 centimetres. Compost or rotted manure makes an excellent mulch and provides additional minerals; asparagus is a heavy feeder. If your mulch is less nutritious, fertilize plants three times a year — spring (before harvest), midsummer and early fall — with a slow-release organic fertilizer that's richer in nitrogen than in phosphorus and potassium. Asparagus, although drought-tolerant, is more productive when kept slightly moist; provide some irrigation in hot, dry weather.
For extra-early spears, rake off the mulch at snowmelt so the ground warms up more rapidly. Once the sprouts are up, keep the harvest weed-free by pushing the mulch back into place, adding more as needed to maintain an eight to 10-centimetre layer.
Through the winter, insulate plants from the damaging freeze/thaw cycle with a 15-centimetre layer of light, airy mulch, such as straw, or cover plants or rows with landscape fabric. Where there's abundant snow cover, no extra protection is needed.
Harvestable shoots begin appearing in mid-spring and continue until early summer. The first year of harvest, take only a few spears so the plant can build up strength. In subsequent years, harvest all spears more than 1.5 centimetres in diameter, leaving the others to grow. In most cases, you'll have a four to eight week harvest period. Cut the plants down to the ground in late fall or early spring for more accessible spears and tidier plants.
Harvest asparagus by cutting or snapping it off. To cut, hold the spear with one hand and cut it about two centimetres below the ground with a sharp knife; you'll probably have to cut off the fibrous base before serving. To snap, simply bend the spear until it breaks. It will snap off naturally, just where the edible part begins.
Asparagus is best eaten fresh but can be stored for a few weeks in the refrigerator. Plunge the base of newly harvested spears into three to five centimetres of cold water, drain and store upright, wrapped in plastic, in the coldest part of your fridge. You can also store them unwrapped, upright in a few centimetres of water in the fridge. Blanch and freeze any surplus.
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