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Capers: A New Crop For California?

Small Farm Center, University of California, Davis, CA 95616

Revised July 1989

By Demetrios C. Kontaxis, Ph.D.

University of California

Pest Management I Public Information Programs Advisor

Contra Costa County

Caper, Capparis spinosa, is a member of the order Capperales, family Caperaceae which contains about 200 species. It is a native of the Mediterranean area, as well as of the tropics. The name caper derives from the Arabic word Kabar. The plant is a deciduous dicot (with two seed leaves and shedding all its leaves each year), and grows about two feet tall and spreading. The vines can be 2-3 meters (or 7 to 10 feet long), and have a very deep root system. The plant is very drought resistant, needs little cultural care, requires good drainage, and is practically free of diseases and insect pests.

The flowers are bisexual with numerous stamens. They are attractive and resemble a rose flower, with white petals and purple shades about 4-6 cm (2 to 2.5 inches) in diameter. The lifespan of the flower is short, about 24-36 hours-but each plant produces hundreds each season. The fruit is green, elongated, 3-5 cm (2-3 inches long), 1-1.5 cm (1/2 - 3/4 inch) in diameter, and contains 200-300 seeds. The leaves are oval in shape, leathery and shiny green. The plant is propagated sexually (by seed) or asexually (by cuttings or roots). The preferred method is the latter simply because of the variability found in seed propagated plants.

The cuttings are rooted in the greenhouse for at least one year and then planted in the field, spaced 5 X 5 meters (about 16 by 16 feet) apart. Field planting takes place during February-March. During the first two summers after planting 2-3 irrigations are required but plants older than 2 years do not need irrigation. Spring fertilization with Ammonium sulfate (21-0-0) or 16-16-l6 at a rate of 1/2 pound per plant per year is advisable. Watering is required after each application.

There is no detailed information on varieties. One group of caper is spineless, C. spinosa, whereas, another bears spines. Both appear to produce equally well.

Mature caper plants are pruned to ground level during November-December. In the spring, tender new shoots develop, which are used as a vegetable and, according to some people, are better than asparagus spears. Buds are picked from mid-May to mid-August. A 2-year old plant will produce some, a 3-year old plant produces just over 2 lbs/year, and a plant older than 4 years may produce over 20 lbs. of buds per year. The unopened buds are picked by hand, sorted into five different qualities and brined in a similar way as cucumbers (Figure 4). The smaller the bud the higher the quality and price. A glass vial of about 200 grams of good quality caper sells for almost $5.00. The fruit is also brined but is considered inferior quality, and is not as important commercially.

Capers are grown commercially in Morocco, Spain and Italy. In Greece, Cyprus, and Turkey the plant is well adapted but it is not cultivated commercially. The United States imports more than $5 million worth of processed capers annually from these countries.

The principal use of capers is as a condiment - in salads or sauces, or with steaks, fish, poultry, or lamb. It is also used to make cosmetics that improve dry skin, and in making certain medicines. Some Capparis species are poisonous. Depending on their use, capers can be considered a vegetable (shoots) or an herb (processed buds).

Besides these food uses, capers can be used as an ornamental - the flowers are numerous and very attractive and the foliage is shiny, deep green. Finally, the plant may be used to control soil erosion, especially on slopes where irrigation is difficult and soil erosion is more pronounced.

Germinating and Transplanting Seedlings

  1. Fill a jar (quart size) with warm water (110-115 F.).
  2. Drop seed into water to soak for at least 12 hours. Let water cool to room temperature. No need to keep water temperature at 110-115 F. for the duration of this treatment.
  3. Discard water, wrap seed in a moist towel, place in a plastic bag and keep in the refrigerator for 65 to 70 days.
  4. Then take seed out of the refrigerator and treat it again as in step #2. No refrigeration necessary this time.
  5. Plant about 1/4 to 1/2 inch deep in a soil mix of 50-25-25 parts planting mix (or U.C. soil), perlite and sand, respectively. Use 6 inch clay pots or deep flats.
  6. Water well and keep in a warm area (70-85 F.), in part to full sun.
  7. Do not let top of soil crust over. Keep soil moist.
  8. Germination should start within 3-4 weeks and may continue for 2-3 months. Not all seeds germinate at the same time.
  9. Let seedlings grow to 3-5 inches tall before transplanting. If seedlings are too crowded in the clay pot or flat do not pull them. Instead, use a scissor and cut off the small, less vigorous, undesirable ones. This way the root system of the remaining seedlings is not disturbed.
  10. Transplant the seedlings to individual one gallon containers, in the same planting mix as above. When transplanting, disturb the root system as little as possible - try to keep some original soil around each transplanted seedling. Good drainage soil is essential to prevent root rot.
  11. Pack the soil tight around the transplanted seedling and water well immediately.
  12. Cover each container with a plastic bag and keep in a shaded spot (if it is spring, summer) or a warm area (70-85 F.) if it is winter. Keep the plastic bag in place for one week.
  13. Then (after 1 week) cut off the top of the bag so that the seedling will be gradually exposed to the natural environment. In another 10 days enlarge the plastic bag opening.
  14. One week later remove the plastic bags and keep in a shaded area.
  15. Keep in the one gallon containers and plant in early spring, after the last frost, when soil is workable.
  16. Plant in elevated rows. The rows should be 8 to 10 feet apart and the plants in each row should be 8 to 10 feet apart.
  17. Water well. Make certain drainage is adequate flooding should be avoided.
  18. Water frequently and fertilize with either 21-0-0 or 16-16-16; two-to-three times during the spring-summer months. Irrigation is essential for the first 2 years of development.
  19. Do not prune the young plant for the first two years.
  20. Prune to the ground (soil surface) 3 year or older plants during November-December.

Note: Caper seed is difficult to germinate. The above methods have resulted in 40-75% germination. Seedlings are very temperamental when transplanted. Some may wilt and die. To reduce this loss, transplant with soil attached to the root system, water and cover with a plastic bag immediately after transplanting. Use mature (dark brown-black) seed, one to two years old. Seeds can be obtained through Park Seed Company, Cokesbury Road, Greenwood, South Carolina, 29647-0001. (803)223-7333. For more information on seeds and seedling sources, contact the author at Contra Costa County Cooperative Extension: (415) 646-6540.

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