The caper plant, Capparis spinosa, is a sprawling, perennial Mediterranean shrub valued primarily for its edible, unopened flower buds. With its rounded, fleshy leaves and attractive, short-lived white flowers, the caper bush offers both ornamental beauty and a distinctive culinary yield. Successful cultivation requires mimicking the plant’s native conditions, focusing on heat, sun, and specific soil and water management.
Establishing the Plant: Climate, Site Selection, and Propagation
The caper bush thrives in regions defined by long, hot summers, typically corresponding to USDA Hardiness Zones 8 through 11. It tolerates high temperatures, easily withstanding conditions above 104 degrees Fahrenheit (40 degrees Celsius). Providing a minimum of six to eight hours of direct sunlight daily is necessary for optimal growth and bud production.
The choice of planting site must prioritize drainage over fertility, as the plant prefers lean, poor soil conditions. Ideal soil should be sandy, rocky, or gravelly to ensure rapid water shedding. A neutral to slightly alkaline pH is preferred, and growers should avoid areas with heavy, moisture-retentive clay soils.
Propagation can be achieved through seed or stem cuttings, though both methods present challenges. Starting from seed often results in erratic germination rates due to the seed’s tough outer coat. To improve success, seeds require scarification and a period of cold stratification, involving refrigeration for several weeks to mimic winter conditions. Cuttings, usually semi-hardwood pieces taken in late winter or early spring, are often the more reliable path for home growers.
Routine Care: Watering, Feeding, and Pruning
Once established, the Capparis spinosa plant is highly drought-tolerant, possessing an extensive root system. Overwatering is the single most common cause of failure, as the plant detests soggy roots. Deep, infrequent watering is the correct approach, allowing the soil to dry out completely between applications. Water stress is beneficial for this plant, as it encourages the formation of flower buds rather than excessive vegetative growth.
The caper bush requires minimal supplemental nutrition and thrives in infertile soil. Over-fertilizing, particularly with high-nitrogen formulas, will promote lush leaf growth at the expense of flower buds. If feeding is necessary, a light application of a low-nitrogen, balanced fertilizer, such as a 5-10-10 formulation, can be used sparingly in the spring. Container-grown specimens may benefit from a light application every four to six weeks during the growing season.
Pruning is necessary because the plant produces flower buds exclusively on new growth. Hard pruning should be carried out in late winter or very early spring, just before the new growing season begins. This involves removing any dead or weak branches and cutting back about one-third of the older, woodier stems to stimulate fresh, bud-producing shoots. The plant’s sprawling habit can also be shaped during this time to maintain a manageable size and form.
Harvesting and Preparation of Caper Buds
The primary harvest consists of the capers themselves, which are the tightly closed, dark green flower buds. Harvesting is a labor-intensive process that must be done by hand, often daily during the peak growing season to ensure the buds remain unopened. Buds should be picked when they are firm and small, ideally less than 7 millimeters in diameter, as these yield the finest flavor and texture.
If the flower buds are not picked, they will bloom into white and pinkish-white flowers that last only a single day. Once pollinated, these flowers develop into oblong, olive-sized fruits known as caperberries. Caperberries are also edible and can be pickled, but they do not possess the same sharp, concentrated flavor as the buds.
Caper buds are bitter and astringent when picked fresh, requiring a curing process before they become palatable. After harvesting, the buds are typically allowed to wilt slightly to reduce moisture content, followed by a long cure in either dry coarse salt or a vinegar-based brine. Salt-curing draws out moisture and bitterness while preserving the caper’s natural flavor, requiring at least two to three weeks. Brining uses a salt-water solution to mellow the bitterness and produce the characteristic tangy flavor.
Managing Dormancy and Cold Protection
As a deciduous perennial, the caper plant sheds its leaves and enters a period of dormancy during the cooler months. This winter rest is normal and necessary. Growth slows significantly during this phase, and watering should be reduced to a minimum until spring.
While the caper plant tolerates heat well, it is vulnerable to freezing temperatures, particularly when young. In climates where frost is a possibility, growers must provide adequate cold protection to safeguard the root crown. For in-ground plants, a heavy layer of organic mulch applied around the base of the shrub helps insulate the roots. Container-grown capers should be moved indoors to a cool, dark, and dry location, such as an unheated garage or greenhouse, for the duration of winter.