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Peppers, Cucumbers and Eggplants in Summer: Polycultures in a Greenhouse

Kako kombinirati tri kralje rastlinjaka za maksimalni pridelek.
July 14, 2025 by
Termoplast

Bell peppers, cucumbers, and eggplants share similar needs, high temperatures, enough water, rich soil. Joint planting in a greenhouse is not only spatially efficient, but also biological: plants support each other through different root systems and pollinators.

3 cultures
from 6 m² greenhouse
12-15 kg
total yield per m²
80 days
from seedling to first harvest

Layout in the greenhouse 6 m² (3×2)

Typical layout for a hobby greenhouse:

  • North side (1 m): cucumbers, the tallest culture, does not shade other plants
  • Middle (1 m): bell peppers and eggplants alternately
  • South side (1 m): low-growing cultures (basil, strawberries)

Spacing:

  • Bell peppers: 40 cm between plants
  • Cucumbers: 50 cm between plants
  • Eggplants: 50 cm between plants

Bell peppers, varieties and care

When it comes to bell peppers, variety selection is crucial. Suggestions for Slovenia:

  • Babura, Slovenian classic, thick flesh
  • California Wonder, large, square
  • Champion F1, early, disease-resistant
  • Habanero Chili, for lovers of spicy food

Care:

  • Remove the first flower (central "crown flower"), strengthens the plant
  • Water evenly (occasional drought + abundance = cracked skin)
  • Fertilize every 14 days with potassium (need for sweet flesh)

Cucumbers, support and pruning

Cucumbers are climbing plants, vertical culture. In the greenhouse, they need a sturdy frame up to 2 m high. Varieties:

  • Marketmore, classic, long fruits
  • Saladin F1, parthenocarpic (without pollination)
  • Kornete for pickling, smaller, ideal for canning

Pruning:

  1. Guide the main stem vertically with a rope
  2. Remove side shoots up to 50 cm high (strengthening roots)
  3. Leave 4-5 side shoots at the top
  4. Remove all flowers on the main stem, fruits grow on side shoots
Pro tip: Harvest cucumbers every day, don't let them over-ripen. Young ones are tastier and encourage further growth.

Eggplants, the forgotten king

Eggplants (aubergines) are not a traditional crop in Slovenia, but they thrive in a greenhouse. The most demanding of the three, they require:

  • 22-28°C all the time (sensitive to cold)
  • Rich soil with 5 cm of mature compost
  • A lot of water: 3-5 L per plant daily at peak
  • Support, a 1.5 m stake

Best varieties: Black Beauty (classic), Long Purple (Italian).

Harvest: when the skin is shiny and firm. When it's dull, it's too late, the flesh is bitter.

Polyculture, rules and combinations

Polyculture has 3 golden rules:

  1. Different heights, high, medium, low level
  2. Different roots, deep and shallow
  3. Mutually beneficial, one feeds the other (legumes + vegetables)

Suggested combinations for a summer greenhouse:

  • Tomatoes + basil + chili peppers (classic Italian)
  • Cucumbers + radishes + dill (radishes as a "trap crop")
  • Bell peppers + garlic + basil (garlic repels aphids)
  • Eggplants + tarragon + chili peppers
"Polyculture is not just capacity, it's also security. If one plant is attacked by disease, the others still stand.", a biodynamic farmer from Prekmurje

More on eco-gardening in the article Ecological fertilization without chemistry.

Typical yield from 6 m² greenhouse with polyculture: 30 kg tomatoes + 15 kg bell peppers + 25 kg cucumbers + 8 kg eggplants = total 78 kg for the family.

Proper greenhouse for polycultures

Sigma 4×3 m has enough space for 3-4 different cultures at the same time. Premium polycarbonate for warm summers and frosty mornings.

Sigma greenhouses
Optimal temperature and humidity in the greenhouse
Kako vzdrževati pravilno klimo skozi vse leto, od zime do najvročjih dni.
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