Caper Bush (Capparis spinosa) Perennial

Grow the Mediterranean's most sought-after delicacy! This hardy, sun-loving perennial yields prized savory buds for gourmet curing. Once established, these drought-tolerant bushes provide decades of elegant blooms and flavorful harvests. Hardiness zones 9-11.

• 40 seeds minimum
• Start indoors for best results. Seeds require cold stratification for successful germination. Sow stratified seeds 1/4" deep in a mix of 50% potting soil, 25% perlite, and 25% sand. Store in warm spot (70–85°F) with moist soil. Germination may take 3 weeks to 3 months. 
• See Annie’s Caper Bush Growing Guide for detailed instructions.
• Mature plants reach 2 to 3 feet in high, spreading 3 to 10 feet wide.

Caper Bush Growing Guide

1. Germination: Overcoming the Challenge
Caper seeds are tough to germinate due to their hard, dormant coats.

• Initial Soak: Submerge seeds in warm water (110–115°F) for 12–24 hours.
• Cold Stratification: Wrap soaked seeds in a damp paper towel, seal in a bag, and refrigerate (40°F) for 65–70 days.
• Second Soak: After refrigeration, soak seeds again in warm water for 24 hours.
• Scarification (Optional): Lightly sand the seed coat to aid water absorption.
• Sowing: Plant seeds 1/4–1/2 inch deep in a mix of 50% potting soil, 25% perlite, and 25% sand.
• Care: Keep soil moist and warm (70–85°F). Germination may take 3 weeks to 3 months.

2. Early Care & Transplanting

• Thinning: Snip weaker seedlings with scissors to avoid disturbing sensitive roots.
• Hardening Off: When seedlings reach 3–5 inches, move them to 1-gallon pots. Gradually acclimate them to outdoor conditions over 2–3 weeks using the plastic bag method.
• Final Site: Choose a sunny location (6–8+ hours of sunlight) with excellent drainage, such as rocky walls or raised beds.

3. Soil, Fertilizer & Maintenance

• Soil Chemistry: Use alkaline soil (pH 7.5–8.5). Amend acidic soil with garden lime or crushed oyster shells.
• Fertilization: Apply a low-nitrogen, high-potassium/phosphorus fertilizer (e.g., 5-10-10 or 16-16-16) 2–3 times during spring and summer.
• Pruning: Flowers grow on one-year-old wood. After the plant is 3 years old, prune heavily in late winter to encourage new growth.

4. Companion Plants
Capers thrive with other Mediterranean plants that love heat and dry, rocky soil:

• Herbs: Rosemary, thyme, sage.
• Flowers: Lavender, rock rose (Cistus), California poppy.
• Succulents: Aloe vera, sedum (stonecrop).

5. Troubleshooting

• Root Rot: Caused by overwatering or clay soil. Let the top 2 inches of soil dry completely before watering.
• Pests: Cabbage White Butterfly caterpillars may attack leaves; use organic Bt spray or hand-pick them.
• Chlorosis (Yellow Leaves): Indicates acidic soil or iron deficiency. Use chelated iron and check soil pH.

6. Harvesting & Curing

• Capers: Harvest unopened flower buds early in the morning when they’re tight and dark green. Smaller buds are more flavorful.
• Caperberries: Allow flowers to bloom and die to produce caperberries, which can also be pickled.
• Curing: Capers must be cured before eating. Soak rinsed buds in coarse sea salt for 1–2 weeks or brine them in equal parts water and white wine vinegar for at least 3 days.

Plastic Bag Hardening-Off Technique

The plastic bag method is a hardening-off technique that eases seedlings from indoor conditions to outdoor environments. Acting as a temporary greenhouse, it stabilizes humidity and protects plants from wind and temperature changes.

Summary of the Method
This method focuses on managing transpiration, as indoor plants develop a thin waxy cuticle and lack the ability to quickly close their stomata.

1. Preparation: Place the seedling in a clear plastic bag, ensuring it doesn’t touch the foliage.
2. Support: Use stakes to prevent condensation from causing rot.
3. Ventilation: Loosely tie the bag or add air holes for gas exchange.
4. Exposure: Start with shaded outdoor placement for a few hours.
5. Gradual Removal: Over 5–7 days, increase exposure and open the bag until it’s fully removed.
6. Caution: Avoid direct sunlight, as the greenhouse effect can overheat and damage plants. Always start in full shade or on cloudy days.

Best That Benefit from This Method

• Nightshades: Tomatoes, peppers, eggplants (sensitive to humidity drops).
• Cucurbits: Cucumbers, melons, squash (large leaves lose moisture quickly).
• Tender Herbs: Basil, cilantro, parsley (prone to wind burn).
• Tropicals: Monsteras, hibiscus, calatheas (mimics jungle humidity).
• Legumes: Runner and pole beans (need structural protection).