Capers come from the caper bush, a hardy perennial shrub known scientifically as Capparis spinosa. The small, round capers you find jarred at the grocery store are the plant’s unopened flower buds, picked by hand before they have a chance to bloom. Native to the Mediterranean, parts of Asia, and the Arabian Peninsula, the caper bush thrives in hot, dry climates where most other plants would struggle to survive.
The Caper Bush Up Close
The caper bush belongs to the family Capparaceae and is sometimes called Flinders rose. It’s a low, sprawling shrub that typically grows about three feet tall and up to six feet wide in its native habitat. The plant produces rounded, fleshy leaves and large white to pinkish-white flowers with dramatic sprays of purple stamens. It drops its leaves in winter and completes its entire active growing season during the driest months of the year, from roughly May through October in the eastern Mediterranean.
What makes the caper bush remarkable is its root system. To survive months of scorching heat with little or no rainfall, its roots can extend downward as deep as 20 meters (about 65 feet) to reach underground water. This deep taproot allows the plant to maintain steady growth and even produce nectar-rich flowers at the peak of Mediterranean summer, when surface soil is bone dry. Researchers studying the plant on Milos Island in Greece found caper roots growing through the walls of ancient catacombs, reaching toward deep soil moisture. The roots also spread horizontally to capture whatever rainfall does occur.
If you’ve traveled through southern Italy or Greece, you may have noticed caper bushes growing wild in stone walls, rock crevices, and cracks in pavement. The plant can reportedly survive several months with no water at all.
Buds vs. Berries: Two Different Products
The caper bush gives us two distinct edible products, and they’re often confused. Capers are the tiny, unopened flower buds harvested before the plant blooms. If those buds are left on the bush, they open into flowers and eventually develop into a larger, olive-sized fruit called a caper berry. Both are eaten pickled or salt-cured, but they have different textures and culinary uses. Capers are dense and intensely flavored. Caper berries are milder, with a softer, almost pickle-like quality and small seeds inside.
Capers are graded and sold by size, with smaller buds considered more desirable (and more expensive). The trade names, from smallest to largest, are: non-pareil (up to 7 mm), surfines (7 to 8 mm), capucines (8 to 9 mm), capotes (9 to 11 mm), fines (11 to 13 mm), and grusas (14 mm and above). Non-pareils have the tightest texture and most concentrated flavor.
How Raw Buds Become Edible Capers
Fresh caper buds straight off the bush are bitter and essentially inedible. They need to be cured before they develop the tangy, briny flavor people associate with capers. The traditional method is dry-salting: freshly harvested buds are mixed with coarse sea salt at about 30 to 40 percent of their weight and turned regularly for 8 to 10 days. During this period, liquid is drawn out of the buds to form a natural brine, and fermentation begins.
After that first stage, the brine is drained off and the buds are packed with a fresh round of salt (20 to 25 percent by weight) for another 20 to 30 days. This extended curing is what produces the complex, slightly pungent flavor that makes capers distinctive. The finished product is typically packaged with additional salt for preservation. Before using salt-packed capers, you soak them briefly in water to reduce the saltiness. Brine-packed capers, the kind most common in American grocery stores, skip this extra step since they’re already stored in a vinegar or salt solution ready to use.
Where the Flavor Comes From
The sharp, almost mustard-like bite of capers comes from sulfur-containing compounds called isothiocyanates. These form when naturally occurring compounds in the plant (glucosinolates) break down during the curing process through enzyme activity. The dominant one is methyl isothiocyanate, the same general family of chemicals that gives mustard, horseradish, and wasabi their kick. The caper bush’s signature glucosinolate, called glucocapparin, is the primary source of this flavor.
Beyond that pungency, capers are unusually rich in a plant compound called quercetin, a type of flavonoid found in many fruits and vegetables. Capers are considered the richest known natural dietary source of quercetin. They also contain a range of other phenolic compounds, including rutin, kaempferol, and chlorogenic acid, which contribute to their antioxidant profile.
Classic Culinary Uses
Capers are a cornerstone ingredient across Mediterranean cooking and well beyond. In Italian cuisine, they’re essential to spaghetti puttanesca (a tomato sauce with olives and anchovies), caponatina (a Sicilian eggplant relish), and chicken piccata, where they’re paired with lemon and butter. Vitello tonnato, a cold veal dish with tuna sauce, features capers as a finishing touch. In France, sole à la Grenobloise combines the buds with browned butter, lemon, and parsley. German königsberger klopse uses them in a creamy sauce over meatballs.
On the other side of the Atlantic, capers are a defining element of the classic bagel with lox and cream cheese. Their briny pop works as a counterpoint to rich, fatty, or mild-flavored foods, which is why they show up so often alongside smoked fish, butter sauces, and soft cheeses. They also pair well with tomatoes, olives, and fresh herbs in salads and grain dishes. A simple rice salad tossed with tuna, tomato, and capers is a common summer dish across Italy.
Growing Capers Outside the Mediterranean
If you live in a warm, dry climate, growing a caper bush is surprisingly feasible. The plant needs full sun, excellent drainage, and very little water once established. It does poorly in humid conditions or heavy, waterlogged soil. USDA hardiness zones 8 through 10 are generally suitable, though the plant’s tolerance for cold is limited. It can handle brief dips below freezing but won’t survive prolonged frost.
The challenge for home growers is patience. Caper bushes are slow to establish and may not produce a meaningful harvest for two to three years. Harvesting is done entirely by hand, picking the small buds every few days before they begin to open. This labor-intensive process is a major reason capers carry a premium price relative to their tiny size. Commercial production remains concentrated in Mediterranean countries, particularly Italy (the islands of Pantelleria and Salina are famous for their capers), Spain, Morocco, and Turkey.