MINTER: Sun and drainage keys to growing asparagus
Asparagus is one of our oldest perennial vegetables. The generic word is derived from the Greek ‘asparagos’ meaning ‘to tear’, which relates to the prickly nature of some stalks.
Asparagus, as one of today’s highly prized gourmet vegetables, is relatively expensive because it takes at least three years from seed until it comes into production; it requires considerable commercial growing area; and it has a limited production season. If you really enjoy this unique vegetable, why not grow your own? Asparagus is hardy from Zones 1-4, meaning it will tolerate temperatures as cold as -40 C. To keep the cost down, commercial growers usually start asparagus from seed but most home gardeners start it from two year old roots. However, by planting four year old roots (you can find these jumbo sized plants in some nurseries), you will save at least one year in harvesting time. Once planted, asparagus roots are productive for at least fifteen years. ‘Mary Washington’ has traditionally been the favourite variety but newer hybrid all-male varieties like ‘Jersey Knight’ produce larger crops of big, attractive green spears with purple bracts and tight purple tips.
To grow asparagus you need a really sunny location with well-drained, slightly alkaline soil. It is very important to make certain the asparagus roots go straight down and because of this, the traditional method of planting involves trenches. Furrows or trenches should be dug about 12 inches wide and 12 to 18 inches deep, depending upon the length of the roots. Rows should be 4 feet apart. The bottom of the trench should be filled with 2 to 3 inches of composted cow, poultry or mushroom manure. Create a mound of soil in the centre of the trench, leaving the crest about 4 inches below the level of the garden soil.
At this point, the asparagus roots can be planted. To speed up the rooting process, I always dip them in a mixture of warm water, root starter fertilizer and mud. This muddy concoction sticks to the roots and immediately begins to stimulate root development.
Lay the roots on top of the mound of soil in the trench, spreading the roots evenly on both sides of this small berm. Place the plants about 18 inches apart and backfill the trench, leaving the crowns or tips of the asparagus just barely covered with soil. Root growth will begin almost immediately.
Weeds can be a problem in new asparagus beds because well established roots will intermingle with the asparagus roots. Keep your asparagus beds weed free by hand cultivation but remember: practice shallow cultivation for fear of injuring the roots.
During the summer, asparagus needs deep watering to keep the roots active and growing. Soaker hoses are the best means of watering these beds. During dry spells, water thoroughly at least once a week. As the asparagus plumes begin to develop, feed the plants with a high nitrogen fertilizer. I prefer to use a slow release food, like 14-14-14, for more long lasting results. It is important to keep the tops growing to develop both food and strength in the roots.
If you are an organic buff, parsley planted with asparagus gives added vigour to both. Tomatoes planted near asparagus will keep away the asparagus beetle because of a substance in the tomato plant called solanine.
The second year after planting, you can begin harvesting a few spears for a period of four to six weeks. When the spears are six to eight inches high, cut them at a 45 degree angle about 1½ inches below the soil line but be careful for fear of damaging the crowns. At the start of the harvesting season, you will probably harvest every three days but as the soil becomes warmer, a daily harvesting can take place. If any spears get away on you, let them develop into foliage. Once the spears become very thin, it’s a sign the roots are near exhaustion and it is time to stop cutting.
Let the plumes grow all summer. In colder parts of British Columbia, leave them standing to trap snow for better winter protection. In the Lower Mainland, the plumes should be cut off in September when the seeds turn red and the roots covered with 4 inches of coarse manure.
It may seem like a fair amount of work the first year but once established, with a little care, you will enjoy your own fresh asparagus for the next fifteen years.
Brian Minter is owner of Minter Gardens in Chilliwack.