Artichokes: tasty thistles adapt to the Northeast
A few years ago Dr. David Hill of the Connecticut Agricultural Experiment Station looked at a map of the Northeast and realized that between Boston and a sizable distance south of New York City lived the greatest concentration of artichoke consumers in the country. Maybe that's because those Americans whose roots go back to the Mediterranean, where the artichoke originated, settled more heavily in this region than elsewhere in the United States. He also recognized the irony of the situation: while most lovers of the tasty thistle live in the Northeast, virtually every grower of consequence lives in the Southwest. The result is high delivery costs and prices you can almost choke on at times. Between Thanksgiving and New Year's Day artichokes can run well above a dollar apiece.
So Dr. Hill set out to develop a system for growing them commercially in the far-from-temperate Northeast. After but a few years of trials his findings suggest that truck farms on the outskirts of New York, Hartford, and Boston may soon be adding artichokes to the lettuce, spinach, butternut squash, and other vegetables that they currently grow for the fresh-produce market. Naturally what the commercial grower can do in a wide open field, the gardener can generally duplicate in the confines of his backyard.
Several mail-order seed companies have also come to recognize the home-garden possibilities of artichokes and now include them in their catalogs. Dick Meiners of Pine Tree Garden Seeds in New Gloucester, Maine, ran what he termed artichoke's ``far-north trials.'' Since they produce a worthwhile harvest in his area, he says there can't be too many places where the artichoke cannot be cultivated successfully.
Artichokes are perennial members of the thistle family whose large flower heads are eaten in the tight bud stage. In their native habitat they experience cool winter rains and warm but not overly hot summers.
The plants grow from seed in one year and may produce some flowers the first year. Heavy flowering, however, occurs the following and in subsequent years. Mature plants can survive cold nights down to 26 degrees F. as long as the temperature climbs above freezing during the day.
Finding a temperature range as benign as the artichoke's native environment is an impossibility in much of the United States. But experimenting growers have found that if adequately protected over winter, the plants will recover and send up new growth the following spring. Even if the crown is killed back they will regrow from the roots to yield a useful harvest the following year. Dr. Hill also discovered a method of getting the artichokes to rush from seed to a significant harvest in just one year.
Overwintering the plants is not easy. ``Tricky,'' is Dr. Hill's expresssion. Dick Meiners piles straw and leaves as a loose mulch after the frost has killed the tops, but Dr. Hill's approach is somewhat different. He cuts back the plants in the fall to two or three inches above the crown and covers them with a waterproof plastic ``pillow'' filled with vermiculite or some other insulation. Over this he inverts a two-gallon pot which he surrounds with leaves or straw. Three stakes hold the pot firmly in place. Professor Hill's aim is to get new flower stalks not just from the roots but from the surviving top vegetation as well.
Another option is to dig up the roots and store them in a cold cellar (between 32 to 40 degrees F.). In the spring, when the roots start sprouting, these new shoots can be separated and set out as individual plants.
With both these overwintering approaches survival rate is a little more than one-third, but because the surviving roots send up so many new plants this loss is not as drastic as it might appear.
Most promising, though, is Dr. Hill's method of getting the artichokes from seed to full harvest in a single season. He does this by giving the seeds a cold treatment (vernalizing is the scientific term), starting them indoors well before planting time, and spraying them once during the growing season with gibberellic acid, a plant-growth hormone. The overall effect is to cram two years' growth and maturity into a single growing season.
This is Dr. Hill's approach:
Soak the seeds in water for two days to help soften the coat.
Mix the seed with damp peat moss in an open plastic bag and refrigerate for between three and four weeks. Check once a week and keep the peat moss damp but not wet. During this period most of the seeds will germinate.
Plant out the sprouted seeds (most should have rootlets between 1/8 and 1/2 inch long) so that the top is level with the surface of the soil in a one-quart or larger greenhouse pot. Use one of the seed starting mixes on the market or a soil that is rich in humus.
From mid-February to mid-April in the North (earlier in the South) place the seedlings in a sunny window. Ideally the temperature should rise to around 70 degrees F. during the day, dropping to around 50 degrees at night.
Move the seedlings to a cold frame to harden off when night temperatures no longer drop more than a degree or two below freezing (mid-April in Connecticut). Keep the cold frame well ventilated during the day unless the air temperature drops to the freezing mark.
After a month of hardening off, the plants are set out three feet apart in rows four feet apart. Dig generous holes enriched with two shovelfuls of compost or aged manure. Or apply a balanced garden fertilizer at rates recommended on the packet.
At the 10-leaf stage Dr. Hill sprays the plants with gibberellic acid. This speeds up growth and generally gets the plant to behave as if it were a lot older than it really is.
Instructions on the bottle will indicate how to get a 100-parts-per-million concentration in your spray. A weaker solution has little effect; a stronger one can burn the leaf tips. Spray the whole plant until the excess begins to drip from the plant.
Mulch with three or so inches of straw or shredded leaves once the summer sun arrives to moderate soil temperatures, and see that the plants get about 11/2 inches of water a week.