Growing Perennial Vegetables
As a group, vegetables are treated as annuals, plants whose life spans average one year. These plants have been harnassed by man and pushed to the limit for maximum production, burning out at the end of their season to be removed for new plants. In San Diego we have placed these vegetables into groups: spring /summer ( to be removed in autumn) and autumn /winter (removed late winter or early spring). Some members of the carrot family (i.e. parsley and cumin) are biennials producing leaves the first year, their seed the second.
The third group is the perennial growers. These include artichokes, asparagus, and strawberries. Berries ( cane and bush) and rhubarb fall into this category as well; however, rhubarb growing in Southern California raises difficulties due to our lack of winter chill and berries require their own article as there are so many. Perennial vegetables require permanent beds and feeding even after food production has ended. If cared for correctly they can last 3 or more years becoming more fruitful as time passes.
As a member of the thistle family, artichokes require little care. They do need room. An established, healthy artichoke will average 5' tall and with time the same width. They are started in three ways : seeds, seedling (or pup) and bareroot chunk. Bareroot ( i.e. all soil is removed from root) is the best, the roots are strong and mature, the draw back is that they can only be pulled and purchased in the winter when the plant is dormant. The side shoots of the artichoke, or pups, are dug up to control the spread of the plant; if sufficient root is attached the small plant can be transplanted and this can be done most times of the year. Since artichokes are thistles, and therefore a weed, the soil preparation is simple. After the hole is dug, size of hole dependent on size of plant or bareroot, a good compost, whether a home product or purchased, is mixed 50/50 with the native soil. When the artichoke is planted water thoroughly.
The myth of asparagus planting involves digging a 1' deep trench, carefully laying the spider like roots across a mound of heavily enriched soil and then covering it. As it grows more and more enriched soil is added (never covering the growing tip) till at last the trench is full. ( At which point the customary sacrifice is held, followed by the standard feast). Sadly I didn't have the time to follow the ritual. This plant is not harvested for 3 to 5 years after planting. So as I was in possession of a raised bed with a tree stump I wanted to decompose, I dug holes around it and planted nutrient hungry asparagus. Each year, in the spring, I dump a 1 cubic foot bag of pure, composted chicken manure on the stump. With each watering the surrounding plants are fed. They love it and the manure is done by the time the asparagus dies back in the winter.
A permanent strawberry bed is a beautiful mass. Dark, leathery leaves with white or pink star like flowers peeking out makes a lovely groundcover. Sweet juicy fruit of a deep red color are an added bonus. It can be a challenge, as snails and pillbugs like to take up residence under the leaves. With the new organic pesticides it is easier to control them. If they do cause a death of plants, the plants can be replaced by runners.Runners are offshoots, long snakes with a new plant on its end, from the mother plant. These new plants can be rooted either in the soil or a pot for removal to another site. After they have rooted ( if after a gentle pull on the runner stem, the plant remains firmly in the soil, it is rooted) cut the stem.
With all these plants feeding is imperative. They should be fed once a month with a complete fertilizer ( having nitrogen, phosphorus and potassium) till they go dormant in the fall.