Can I Put Up a Greenhouse on My Allotment?

Introduction

A greenhouse on your allotment allows you to extend the growing season, protect plants from frost, and cultivate a wider variety of crops. With the right setup, a greenhouse can enhance productivity, enabling you to start seedlings early, grow heat-loving plants, and even harvest vegetables year-round. However, before putting up a greenhouse, it’s essential to consider allotment rules, greenhouse options, and positioning. This guide covers everything you need to know about setting up a greenhouse on your allotment, from checking regulations to choosing the best design and maintaining your structure.

1. Check Allotment Rules and Permissions

Before setting up a greenhouse, verify that your allotment allows permanent structures and check any specific rules or restrictions.

Review Allotment Regulations

Local Council or Allotment Association Rules: Some councils or associations have guidelines on greenhouse size, materials, and placement. Reach out to your allotment manager or association to confirm these.
Size and Height Restrictions: Many allotments restrict the size and height of greenhouses to avoid shading neighboring plots. Confirm the maximum allowable dimensions before purchasing or building a greenhouse.

Apply for Permission if Necessary

Formal Approval: Some allotments require a written request or approval process for structures like greenhouses. Prepare a simple proposal outlining the greenhouse size, materials, and location.
Avoid Permanent Foundations: In most cases, avoid concrete foundations, as allotments typically allow temporary structures only. Instead, opt for removable bases like paving slabs or gravel.

2. Choose the Right Greenhouse Type for Your Allotment

Greenhouses come in various shapes and sizes, from compact cold frames to larger walk-in models. Choose a greenhouse type that fits your space and meets your gardening needs.

Traditional Glass or Polycarbonate Greenhouses

Benefits: These offer excellent light transmission and insulation, ideal for starting seedlings and growing heat-loving plants.
Considerations: Glass greenhouses are durable but more fragile than polycarbonate. Polycarbonate is shatterproof, safer for allotments, and provides UV protection for plants.

Polytunnels

Benefits: Polytunnels are cost-effective, flexible, and available in various sizes. They’re easy to set up and take down if necessary.
Considerations: Polytunnels may not insulate as well as glass but are ideal for creating a warm growing environment and extending the growing season.

Cold Frames or Mini Greenhouses

Benefits: Cold frames and mini greenhouses are compact, affordable, and don’t require much space, making them ideal for smaller plots.
Considerations: These options offer limited space but are perfect for hardening off seedlings, growing herbs, and extending the season for smaller plants.

3. Choose the Right Location on Your Allotment

Positioning your greenhouse correctly on the allotment ensures that plants receive optimal sunlight and protection from strong winds.

Consider Sunlight

South-Facing Location: A south-facing position allows the greenhouse to capture maximum sunlight, essential for winter growing.
Avoid Shade from Trees or Structures: Place the greenhouse in a clear area without shading from trees, fences, or neighboring plots, as this could limit light availability.

Shelter from Strong Winds

Wind Protection: Position the greenhouse in a sheltered area, or install windbreaks if your allotment is exposed. Windbreaks reduce heat loss and prevent structural damage.
Anchor the Structure Securely: Use ground anchors, pegs, or weight the base with slabs to secure the greenhouse against strong winds, especially if using a lightweight structure like a polytunnel.

4. Preparing the Base and Setting Up the Greenhouse

A stable, level base ensures your greenhouse is sturdy and provides a clean, weed-free surface for growing.

Create a Level Surface

Paving Slabs or Gravel Base: Lay paving slabs or gravel to create a flat, well-drained surface. Paving slabs are easy to remove if needed and provide a stable base.
Avoid Soil Bases: Avoid placing the greenhouse directly on soil, as this can allow weeds and pests to enter. A gravel or slab base reduces maintenance and improves drainage.

Secure the Frame

Use Ground Anchors: Secure lightweight structures, like polytunnels, with ground anchors or metal pegs, especially if your allotment is in a windy area.
Ensure Stability: Double-check that the frame is level and stable to prevent shifting, which could damage the greenhouse or cause issues with door and window operation.

5. Organize the Interior for Efficient Growing

An organized greenhouse maximizes productivity by making it easy to care for plants and monitor conditions.

Install Shelving and Staging

Vertical Growing Space: Use shelves or staging to make the most of vertical space, ideal for starting seedlings or growing compact crops like herbs.
Adjustable Shelving: Choose adjustable shelving so you can modify the layout based on plant height, maximizing space for a variety of crops.

Plan for Ventilation and Temperature Control

Ventilation Windows or Vents: Proper ventilation prevents overheating and reduces humidity, which can lead to mold and pest problems. If possible, install roof vents or side windows.
Use Shade Cloth or Paint: In summer, use shade cloth or greenhouse paint to reduce heat buildup, keeping the greenhouse cool and protecting plants from sunburn.

6. Manage Temperature and Humidity in Your Greenhouse

Temperature and humidity control are crucial to ensure healthy plant growth and prevent common issues like mold and mildew.

Heating Options for Winter

Electric or Solar Heaters: Small electric or solar-powered heaters can maintain temperatures during cold months, especially for tender plants.
Thermal Mass (Water Barrels): Place dark-colored water barrels in the greenhouse to absorb and release heat, helping regulate temperature without additional equipment.

Control Humidity Levels

Water Plants Early in the Day: Watering in the morning allows moisture to evaporate throughout the day, reducing humidity.
Use Gravel Trays for Moisture-Loving Plants: For plants that need high humidity, place pots on gravel trays filled with water, which evaporates slowly to maintain localized humidity.

7. Choosing Crops for Greenhouse Growing

A greenhouse allows you to grow a wide range of crops, including early-season plants, tender vegetables, and winter greens.

Early-Season Seedlings

Start Seeds Earlier: Use the greenhouse to start tomatoes, peppers, cucumbers, and other heat-loving crops early, extending your growing season.
Transplant Outdoors in Spring: Harden off seedlings before transplanting them outdoors for a strong start to the season.

Heat-Loving Summer Crops

Tomatoes, Peppers, and Cucumbers: These plants thrive in the warmth and protection of a greenhouse, producing higher yields than outdoors.
Melons and Aubergines: If you have enough space, try growing melons and aubergines, which require a long, warm growing season and thrive in greenhouse conditions.

Winter Greens

Lettuce, Spinach, and Chard: Grow winter greens in a greenhouse for a continuous harvest, even in colder months.
Hardy Herbs: Herbs like parsley, cilantro, and rosemary do well in winter greenhouses, providing fresh herbs year-round.

8. Maintaining Your Greenhouse Throughout the Year

Regular maintenance keeps your greenhouse efficient, extends its lifespan, and ensures healthy plant growth.

Seasonal Cleaning

Disinfect Annually: Clean the greenhouse at least once a year to remove algae, pests, and disease-causing pathogens. Use a mild disinfectant and scrub surfaces thoroughly.
Clear Out Old Plants: Remove old plants, weeds, and fallen leaves to prevent pests and diseases from building up over winter.

Inspect for Damage and Repairs

Check for Cracks or Tears: Inspect glass panels, polycarbonate, or polytunnel covers for damage. Repair any cracks or tears promptly to maintain insulation.
Tighten Fixtures and Seals: Regularly check bolts, screws, and seals to ensure the structure remains stable, especially after extreme weather.

Conclusion

A greenhouse can transform your allotment by extending the growing season, protecting plants, and enabling year-round cultivation of a wider variety of crops. By understanding allotment regulations, choosing the right greenhouse type, positioning it for optimal sunlight, and maintaining it effectively, you can create a productive growing environment on your plot. With the right crops, seasonal care, and organization, a greenhouse will enhance your allotment and provide fresh produce for more months of the year.