How to Grow Capers UK

When to Plant Capers in the UK

When to plant capers in the UK: in Southern England, sow early March to late April. Find your area in the table below.

Region	Sow
Southern England	early March to late April
Midlands	early March to late April
Northern England	early March to late April
Scotland	early March to late April

Southern England - detail & sources

RHS grows caper under glass in the UK, potting on and starting seed in spring; plants can move outdoors for summer only, given a sheltered, south- or west-facing spot -- H1C hardiness (5-10°C minimum) rules out year-round outdoor growing anywhere in the UK.

Midlands - detail & sources

Same under-glass regime as elsewhere in the UK -- RHS's H1C rating means this crop is never grown outdoors year-round regardless of region.

Northern England - detail & sources

Same under-glass regime as elsewhere in the UK -- RHS's H1C rating means this crop is never grown outdoors year-round regardless of region.

Scotland - detail & sources

Same under-glass regime as elsewhere in the UK -- RHS's H1C rating means this crop is never grown outdoors year-round regardless of region.

Quick Facts

Factor	Value
Drainage	Loam and sand, very sharp drainage (RHS/Wisconsin Horticulture); tolerates drought well once established.
Lifecycle	Tender, sprawling shrub. RHS rates it H1C (5-10°C minimum) -- grown outdoors in summer in the UK but needing shelter or a container life the rest of the year. Wisconsin Horticulture gives a USDA zone 8 minimum, noting plants lose all their leaves in winter where only marginally hardy.
Edible parts	flower_buds, fruit

At a Glance

Growth Stages

Stage	BBCH	Notes
Propagation and potting	0	RHS: sow seed soaked in warm water for 2-3 days beforehand, at 18-21°C -- germination is slow and erratic. Wisconsin Horticulture: fresh seed germinates best; stored seed needs scarification and/or cold stratification and can take up to three months, or propagate by softwood/hardwood cuttings.
Establishment	3	RHS: grow under glass in peat-free, loam-based compost with added grit; water moderately in the growing season with a monthly high-potash feed, sparingly in winter. Wisconsin Horticulture: needs very sharp drainage and limited water, similar to olive-growing conditions -- once established plants are notably drought-tolerant.
Flowering	6	RHS: in summer, plants produce white, four-petalled flowers with a tuft of white-to-pink stamens above round, grey-green leaves to 4cm across on a sprawling shrub to 1m tall.
Bud harvest	8	Wisconsin Horticulture: harvest unopened flower buds by hand while still dark olive-green and about the size of a corn kernel; the intense caper flavour only develops after picking, as mustard oil (glucocapparin) is released from the bud.

Harvest & Storage

When to pick: Wisconsin Horticulture: pick unopened flower buds by hand while dark olive-green and about the size of a corn kernel, mid-May to mid-August, ideally in early morning while buds are still tight.

Storage

Sun-dry the buds, then brine, salt, or pickle (Wisconsin Horticulture). Caperberries are also pickled.

Pests

Mealybugs

low

Pseudococcidae

RHS: may be susceptible to mealybugs under glass. Wisconsin Horticulture does not mention any significant pest problems, consistent with wider reporting that capers are largely pest-free.

Caper, Seed to Harvest

The showy flower

RHS describes four white petals surrounding a tuft of white-to-pink stamens -- the flower itself is one of caper's most ornamental features, even before the buds are picked.

A single caperberry

The long-stalked, olive-shaped fruit -- caperberries -- are pickled whole, seeds and all, unlike the flower buds which are picked before they open.

Grey-green foliage

RHS describes round, grey-green leaves up to 4cm across on a sprawling shrub -- a texture and colour typical of drought-adapted Mediterranean plants.

A wall-dwelling habit

Caper is famous for rooting in the smallest crack in old stone or brick walls -- both RHS and Wisconsin Horticulture note its need for very sharp drainage, which crevice growing supplies naturally.

A ground-hugging mat

Wisconsin Horticulture describes semi-prostrate branches spreading 6-10ft wide from a plant only about 3ft tall -- caper spreads far more than it grows upright.

A handful of caperberries

Larger, riper fruits left to develop past the bud stage become caperberries, pickled and sold with their stalks still attached.

Flower structure up close

Held in the hand, the flower's structure is easy to see: four broad white petals beneath a dense cluster of long stamens.

A closer look at the stamens

The purple-tinted filaments and prominent stamens are part of what makes caper flowers stand out, even though it's the unopened bud, not the flower, that becomes the culinary caper.

Bud to fruit, side by side

Buds, an open flower, and ripening fruit shown together -- Wisconsin Horticulture notes the intense caper flavour only develops after the bud is picked, as mustard oil is released.

What university and government growers’ guides add about caper bush

The caper bush is a plant of hot, dry Mediterranean rock, and both sources below say it is cold that limits it, not heat.

• It prefers dry heat and intense sun, and thrives in poor, dry, rocky or sandy soils. (Purdue, Missouri Botanical Garden)
• It is cold tender. Purdue compares its hardiness to the olive tree (about −8°C, 18°F), and Missouri Botanical Garden says plants will not survive winter when temperatures dip below 18°F. (Purdue, Missouri Botanical Garden)
• It grows well in nutrient-poor, sharply drained, gravelly soils, is salt tolerant, and easily survives summer temperatures above 40°C (105°F). (Purdue)
• Purdue says plants are productive where about 350 mm of rain a year falls, mostly in winter and spring; Missouri Botanical Garden says established plants need little watering. (Purdue, Missouri Botanical Garden)
• Capers are the flower buds, picked while still tight before they open, washed in salt water to remove grit, dried, and then salted or pickled in vinegar. (Missouri Botanical Garden, Purdue)

Sources for this section

• Purdue University Center for New Crops and Plant Products: Caper, Capparis spinosa (Crop Fact Sheet)
• Missouri Botanical Garden: Capparis spinosa (Plant Finder)

Section researched and checked on 24 October 2026 by the SoilCommander Editorial Team. How we check facts: editorial policy.

References

1. Royal Horticultural Society - Capparis spinosa (common caper, caper)

   Hardiness H1C (5-10°C minimum). Soil: loam and sand, well-drained, acid/alkaline/neutral pH tolerant. Sun/aspect: full sun, south/west-facing. Exposure: sheltered. Size: 0.5-1m height and spread, 2-5 years to maturity. Under glass: peat-free loam-based compost with added grit; water moderately in growing season with monthly high-potash feed, sparingly in winter. Propagation: seed soaked in warm water 2-3 days before sowing at 18-21°C, germination slow and erratic. Pests: may be susceptible to mealybugs. Diseases: generally disease-free. Growth habit: tender, sprawling shrub to 1m, round grey-green leaves to 4cm; white four-petalled flowers with white-to-pink stamens in summer; unopened buds pickled/salted as capers, long-stalked olive-shaped berries eaten as caperberries.

2. University of Wisconsin-Madison Division of Extension (Wisconsin Horticulture) - Capers, Capparis spinosa

   Light: high light intensity required. Soil: dry, sandy or gravelly, very sharp drainage, limited water, similar to olive-growing regions. Size: ~3ft tall, semi-prostrate branches spreading 6-10ft wide. Hardiness: zone 8 minimum; technically evergreen but loses leaves in winter where marginally hardy; Midwest plants must come indoors before frost. Native range: wild throughout the Mediterranean and other areas, native status unclear. Propagation: seed or softwood/hardwood cuttings; fresh seed germinates best, stored seed needs scarification/cold stratification with sporadic results, often taking up to 3 months. Harvest: unopened buds picked by hand when dark olive-green, about the size of a corn kernel; intense flavour develops after picking as mustard oil (glucocapparin) releases; buds sun-dried then brined/salted/pickled; larger fruits (caperberries) also pickled; dried leaves used as a rennet substitute in cheesemaking. Not commonly cultivated in the US; suited to container growing as a novelty plant in warm climates.

2 independent sources are cited for this crop. Where they disagree - soil pH is the clearest case - every figure is preserved rather than averaged into false precision.