Growing Tomatoes: A Comprehensive Guide for Greenhouse and Outdoor Cultivation

Tomatoes are a beloved crop for many gardeners, providing a bounty of delicious fruits that can be enjoyed fresh, cooked, or preserved. Whether you’re growing tomatoes in a greenhouse or outdoors on your allotment, this guide will help you achieve a successful and bountiful harvest in the UK.

Choosing the Right Tomato Varieties

Different tomato varieties are suited to greenhouse or outdoor growing. Consider the following:

  • Greenhouse Varieties:
    • 'Sungold'
    • 'Gardener's Delight'
    • 'Moneymaker'
    • 'Shirley'
  • Outdoor Varieties:
    • 'Outdoor Girl'
    • 'Alicante'
    • 'Roma'
    • 'Sub Arctic Plenty'

Preparing the Soil

Tomatoes thrive in fertile, well-drained soil. Here’s how to prepare your soil for both greenhouse and outdoor planting:

  1. Clear the Area: Remove weeds, rocks, and debris.
  2. Loosen the Soil: Use a garden fork or tiller to loosen the soil to a depth of about 12 inches.
  3. Amend the Soil: Add compost or well-rotted manure to improve fertility and soil structure.
  4. pH Level: Aim for a soil pH of 6.0-6.8. Adjust if necessary with lime (to raise pH) or sulfur (to lower pH).

Sowing Seeds and Planting Seedlings

Start tomato seeds indoors 6-8 weeks before the last expected frost. Here’s how:

  1. Seed Sowing: Sow seeds in seed trays or small pots filled with seed compost. Sow seeds 1/4 inch deep and keep the compost moist.
  2. Germination: Place trays in a warm area (18-21°C) and ensure they receive plenty of light. Germination typically occurs within 7-14 days.
  3. Transplanting: Once seedlings have two sets of true leaves, transplant them into larger pots. Harden off seedlings before planting them in the greenhouse or outdoors.

Planting in the Greenhouse

  1. Timing: Transplant seedlings into the greenhouse in late April to early May when they are about 6-8 inches tall.
  2. Spacing: Space plants 18-24 inches apart in rows 24-36 inches apart.
  3. Support: Install stakes or tomato cages to support the plants as they grow.
  4. Watering: Water regularly, keeping the soil consistently moist but not waterlogged. Use a drip irrigation system if possible.

Planting Outdoors

  1. Timing: Transplant seedlings outdoors in late May to early June, after the last frost date.
  2. Spacing: Space plants 18-24 inches apart in rows 24-36 inches apart.
  3. Support: Use stakes or cages to support the plants.
  4. Mulching: Apply a layer of mulch around the plants to retain moisture, regulate soil temperature, and suppress weeds.

Care and Maintenance

Proper care is crucial for a healthy tomato crop:

  • Feeding: Use a balanced fertilizer when planting. Once flowers appear, switch to a high-potassium fertilizer to encourage fruiting.
  • Pruning: For indeterminate varieties, remove side shoots (suckers) that develop between the main stem and leaves. This helps direct energy to fruit production.
  • Watering: Water regularly and deeply. Avoid overhead watering to reduce the risk of fungal diseases.
  • Ventilation: Ensure good airflow in the greenhouse to prevent disease. Open vents or doors on warm days.

Pest and Disease Control

Common tomato pests and diseases include:

  • Aphids: Control with insecticidal soap or natural predators like ladybirds.
  • Blight: Remove affected leaves and plants immediately. Choose resistant varieties and practice crop rotation.
  • Whiteflies: Use yellow sticky traps and encourage beneficial insects.

Harvesting

Tomatoes are ready to harvest when they are fully coloured and slightly soft to the touch:

  • Greenhouse Tomatoes: Typically harvested from late June to September.
  • Outdoor Tomatoes: Usually ready from late July to early October.

Storing and Using Your Harvest

  • Fresh Storage: Store tomatoes at room temperature until ripe, then refrigerate.
  • Preserving: Can, freeze, or dry excess tomatoes to enjoy them year-round.

Conclusion

Growing tomatoes on your allotment, whether in a greenhouse or outdoors, is a rewarding experience that can yield an abundance of flavourful fruits. By following these guidelines, you’ll ensure a successful and plentiful harvest. Enjoy the process and the delicious results of your hard work!