VARIETIES

Spineless and spiny types exist. The spineless types are preferred. Named varieties are difficult to find in U.S. seed catalogs. Often the only option is a generic cardoon with no variety mentioned. 'Tenderheart' and 'Gigante' can be found in some current catalogs. One may also search European catalogs. Varieties recently available included Bianco Ameliore, Italian Dwarf, Large Smooth, and White Improved. Any of the above can be considered suitable for trial in the Pacific Northwest.

Caution: Cardoon is considered a nuisance weed in some areas of Northern California. Cardoon produces hundreds of seeds that float on the winds and reach locations that are very difficult to reach by ground-based weed-abatement teams. These hard-to-reach places become sources of seed for infestations of crop and rangeland. Cardoon is very hardy and prolific in areas with mild winter climates.

CLIMATIC REQUIREMENTS

Cardoon does best in a frost-free coastal area with cool foggy summers. It is closely related to the globe artichoke but is more vigorous and tolerant of climatic variations. Leaves can reach 3-5 feet in length with crowns 4-6 inches in diameter under ideal conditions. Cardoon will be inedible when grown under hot conditions due to the strong bitter compounds that form.

SOIL

Cardoon is a perennial plant that will grow on a wide range of soils, but it produces best on a deep, fertile, well-drained soil. The plant is deep rooted and should be planted on soils that afford adequate area for root development. Steady, uniform growth throughout its entire growth period is important for good quality product.

SEEDING AND TRANSPLANTING

Cardoon seed numbers approximately 700 per ounce, with approximately 4-5 lb seed needed per acre. Production is best when transplants are grown and set out in spring, but direct seeding may also be used. For transplants, sow seed in the greenhouse in early or mid-March for transplanting in mid-May for October or November harvest. Cardoon is sensitive to frost.

Direct seed in the field in early to mid May and thin to a final stand. Seed or transplant into an 8 to 10-inch deep trench and cover seed with about 1 inch of soil. As plants grow additional soil is added until the trench is filled.

Like artichokes, cardoon may also be propagated from stem pieces or suckers that develop off the main stem.

Space plants 18-24 inches apart in rows 36-48 inches apart.

FERTILIZER

Fertilizer applications should be made according to current soil test information. The following are general recommendations:

Twenty-30 tons/acre of manure, if available, worked in before planting.

Nitrogen: 60-100 (N) lb/acre - Apply all at one time in early spring before buds begin to form.
Phosphorus: 100-200 (P205) lb/acre - Broadcast and worked in before planting.
Potash: 100-200 (K20) lb/acre - Broadcast and worked in before planting.
Sulfur: 15-25 (S) lb/acre - Broadcast and worked in before planting.

IRRIGATION

Cardoon requires a uniform supply of moisture. Leaves and stalks become pithy when subjected to water stress, making them unmarketable. About 10-12 inches of water, uniformly distributed throughout its growing period may be necessary.

Soil type does not affect the amount of total water needed, but does dictate frequency of water application. Lighter soils need more frequent water applications, but less water applied per application.

HARVESTING, HANDLING, AND STORAGE

As the leaves near maturity, they are tied together near the top and the plants are then wrapped in burlap, paper, or other material to blanch the leaf stalks or petioles. Generally 4-5 weeks may be needed for blanching.

Harvest commences about 120 to 150 days after planting. The blanched plant parts are harvested by cutting just below the crown and trimming excess loose leaves off, leaving only the trimmed, blanched heart some 18-24 inches in length and 2-3 inches in diameter.

Cardoon hearts are seldom stored; but for temporary holding a temperature of 32 F is recommended, with a relative humidity of 95 to 100 % to prevent wilting or drying. Cardoon of good quality without decay or freezing injury will keep in good condition for 2 to 3 weeks at 32 F.

PACKAGING

Consult buyers as to their packaging requirements.