Globe Artichoke

Introduction

Globe Artichoke (family AsteraceaeCynara cardunculus var. scolymus) is the large harvested flower bud of a thistle of Mediterranean origin. The edible portions include both the fleshy bases of the bracts that surround the bud as well as the tender core (heart) that supports the immature florets in the center of the bud. If buds are not harvested and are allowed to flower, the blue/lavender blossoms make excellent bee forage or additions to floral bouquets.  Artichoke is closely related to cardoon (C. cardunculus var.) which is grown primarily for its fleshy stems and often eaten braised or fried. In mild climates where temperatures do not remain below 50 degrees F for prolonged periods, globe artichoke is a perennial crop that is propagated vegetatively. Breeding efforts have produced cultivars that reliably flower in the first year after a vernilization period of exposure to cool temperatures (below 50°F) for 8 to 10 days in the spring. These varieties can be grown successfully in New England.

Varieties

Globe ARTICHOKE VARIETIES
Imperial Star
Emerald

Soil Fertility

Apply lime according to test to maintain soil pH between 6.5 and 7.0.

PLANT NUTRIENT RECOMMENDATION ACCORDING TO SOIL TEST RESULTS FOR Globe ARTICHOKE
Globe ARTICHOKE   PHOSPHORUS (P) LBS P2O5 PER ACRE POTASSIUM (K) LBS K2O PER ACRE
SOIL TEST RESULTS NITROGEN (N)* LBS PER ACRE VERY LOW LOW OPTIMUM ABOVE OPTIMUM VERY LOW LOW OPTIMUM ABOVE OPTIMUM
Broadcast and Incorporate in fall 100 75 50 0-25 0 150 100 50 0

Sidedress 3-4 weeks later 

0-50

0

0

0

0

0

0
TOTAL RECOMMENDED 120 75 50 0-25 0 150 100 50  0

 

Planting

Artichokes should be seeded 8 to12 weeks before setting transplants outdoors with at least 4 leaves in 4" pots. Space plants 2 to 3' apart in rows 4 to 5' apart. Germination may be improved by soaking seeds for 48 hrs and germinating at 70 to 80°FPlants require a chilling period ( vernalization) to induce flowering. The amount of chilling required varies with variety. Imperial Star needs approximately 250 hours (ten days) below 50°F. The easiest way to accomplish this is to time transplanting so that young transplants receive this exposure outdoors, covering plants if frost is expected. For late transplanting dates, plants may need to be atrificially vernalized.

Field Culture

If somewhat complicated to start, this crop is mostly trouble free in the field with few pests, and offers New England customers a fresh Mediterranean treat. In the field, globe artichoke requires a bit of space; 2 to 3' apart in rows, 4-6' apart. Research in New Jersey showed that using black plastic mulch reduced yields, possibly because higher root zone temperatures can reverse the effects of vernalization. Straw or reflective silver mulch are good alternatives to keep soil temperatures cooler. Plants should begin budding in late July. Pinching off some of the smaller buds can encourage the larger ones to size up. At the end of the season the healthiest artichoke plants with several side shoots can be split and planted into unheated high tunnels under row cover for an early June harvest the following year. Supplemental irrigation may be required in field and tunnel crops as stressed plants are more susceptible to the "black tip" disorder. Plants should receive one inch of water per week to avoid this.

Harvest and Storage

Yields vary, but 2 to 3 primary buds per plant are average, with 8 to 10 secondary smaller buds per plant possible. Artichokes are marketed in 22 lb cartons. Marketable buds are graded in the following classes: 18's are larger than 4.5" in diameter; 24's are 4-4.5"; 36's are 3.5-4" and 48's are 3-3.5".  Average diameters in New England tend to fall between 3-4".  These smaller buds are popular in France as they are tender and roast well, developing sweetness. Buds are harvested with 2 to 3 inches of stem attached when they have reached their maximum size, but before the lower bracts begin to spread apart or toughen. Overmature buds can become bitter and tough. After harvest, buds should be cooled quickly and stored at temperatures close to 32° F, but should not be allowed to freeze.