Tomato Growing in Polytunnels

Polytunnels are a budget-friendly way to extend your tomato season, protect plants from bad weather, and produce bigger, sweeter crops. Here’s everything you need to know for polytunnel tomato success—from setup to harvest.

Why Grow Tomatoes in a Polytunnel?

• Warmer Climate:
  Extends the growing season, allowing early planting and late harvests.
• Rain Protection:
  Reduces risk of blight and leaves stay dry—less disease!
• Consistent Environment:
  Easier to manage temperature, humidity, and airflow than outdoor beds.

Setting Up Your Tomato Polytunnel

• Best Varieties:
  Indeterminate/vining tomatoes thrive—try ‘Gardener’s Delight,’ ‘Ailsa Craig,’ ‘Shirley,’ ‘Sungold,’ or your favorite cherry and beefsteak types.
• Soil Prep:
  Dig in compost or well-rotted manure. Renew or change topsoil annually to reduce disease buildup.
• Spacing:
  18–24 inches (45–60cm) between plants for airflow and easy access.
  Leave wide paths for watering and harvests.
• Supports:
  Use tall bamboo canes, string lines from the roof, or wire trellis—plants can easily reach 6 feet+ in a good season.

Polytunnel Care Tips

• Ventilation:
  Open ends/vents daily. Avoid high humidity—polytunnels heat up fast in sun!
• Watering:
  Consistent watering is vital—tomatoes in tunnels dry out quickly but hate being waterlogged. Drip irrigation is ideal.
• Mulching:
  Use compost, straw, or grass clippings to retain soil moisture.

Pollination

• Gently shake stems or flower trusses during blooming, or tap supports daily—no wind means less natural vibration!
• Open doors to encourage bees on warm days.

Feeding

• Start high-potash tomato fertilizer as soon as first flowers appear, repeating every 7–10 days during heavy fruiting.

Common Challenges

• Whitefly, aphids, and spider mites can thrive—check plants regularly and use organic controls if necessary.
• Overheating—shade or use whitewash on plastic, ventilate well on hot days.

Harvesting

• Pick fruits as soon as ripe for best flavor and to encourage further production.
• Watch for split fruit after heavy watering—consistent moisture prevents cracking.