Greenhouses provide a controlled environment that extends your growing season, shields plants from pests, and allows for the cultivation of a wide variety of plants in any weather.

To make the most of your greenhouse, it’s important to understand the unique challenges and opportunities it presents.

In this guide, we’ll explore the best tips for growing plants in a greenhouse, with a focus on timber-framed polycarbonate greenhouses, to help you cultivate a thriving garden.

Best Materials for a Greenhouse

When selecting a greenhouse, the choice of materials is crucial for both the structure’s durability and the plants’ well-being. Timber-framed polycarbonate greenhouses combine the natural aesthetics of wood with the strength and light diffusion benefits of polycarbonate panels.

• Timber Frame: Timber provides a natural, aesthetic appeal that blends seamlessly with garden environments. It’s also a great insulator, helping to maintain stable temperatures within the greenhouse. Additionally, timber is durable and can withstand various weather conditions, making it ideal for New Zealand’s diverse climate.
• Polycarbonate Panels: Unlike traditional glass, polycarbonate panels are lightweight, virtually unbreakable, and provide superior UV protection. They diffuse sunlight evenly, reducing the risk of plant scorching while allowing enough light for photosynthesis. This creates an ideal growing environment for a wide range of plants.

Optimise Temperature Control

Effective temperature regulation is critical in greenhouse gardening, especially in New Zealand’s variable climate. Greenhouses can quickly become too hot or too cold, so maintaining a stable temperature is essential.

• Ventilation: Ensure your greenhouse has adequate ventilation.
• Shading: Install shading materials such as shade cloth or netting to protect your plants from excessive sunlight and prevent overheating. This is particularly important in summer when temperatures can soar.
• Heating: In colder months, consider installing a heater or using thermal mass materials like water barrels to help retain heat. Timber frames also provide natural insulation, helping to maintain a warmer environment.

Maintain Humidity Levels

Greenhouses naturally have higher humidity levels due to the enclosed space and transpiration from plants. However, excessive humidity can lead to fungal diseases and mould growth.

• Water Wisely: Water your plants in the morning to allow excess moisture to evaporate during the day. Overwatering can increase humidity, so be mindful of your watering schedule.
• Ventilation: Adequate ventilation helps regulate humidity levels and ensures a healthy growing environment for your plants.
• Humidity Trays: In dry conditions, especially if you’re growing tropical plants, place trays filled with water under benches to increase humidity.

Use the Right Soil and Fertiliser

The soil quality in a greenhouse can deplete quickly due to the confined space and intense growing conditions. It’s crucial to use the right soil and replenish nutrients regularly.

• Soil Choice: Use a high-quality potting mix that is well-draining. Adding organic matter like compost can improve soil structure and fertility.
• Fertilisation: Greenhouse plants often need more frequent fertilisation due to the controlled environment. Use a balanced fertiliser and consider a slow-release formula for convenience.

Monitor for Pests and Diseases

While greenhouses offer protection from many pests, they can still harbour insects and diseases if not managed properly.

• Inspect Regularly: Check your plants frequently for signs of pests like aphids, whiteflies, and spider mites. Also, look out for fungal diseases such as powdery mildew.
• Biological Controls: Introduce beneficial insects like ladybirds or parasitic wasps to control pests naturally.
• Sanitation: Keep the greenhouse clean by removing dead leaves, old plant material, and any debris that could harbour pests or diseases.

Tip: Consider using sticky traps or natural pest deterrents to keep unwanted guests at bay.

Maximise Space with Strategic Planting

Greenhouse space is often limited, so make the most of it by using vertical gardening techniques and strategic planting.

• Shelving and Benches: Use shelves and benches to increase planting space. This also helps in organising plants based on their specific light and temperature needs.
• Vertical Gardens: Install trellises or hanging baskets to grow vining plants or small vegetables. This not only saves space but also adds visual interest.

Tip: Group plants with similar care requirements together to make watering and maintenance easier.

Plan for Year-Round Growing

One of the biggest advantages of a greenhouse is the ability to grow plants year-round. However, this requires careful planning and management.

• Crop Rotation: Practice crop rotation to prevent soil-borne diseases and pests. Rotate between different plant families to maintain soil health.
• Succession Planting: Plant crops in succession to ensure a continuous harvest. For example, start with cool-season crops like lettuce and radishes, and follow with warm-season crops like tomatoes and peppers.

Tip: Use a planting calendar to plan your greenhouse activities throughout the year.

Use Companion Planting to Boost Growth

Companion planting is the practice of growing different plants together for mutual benefits. This can help improve growth, deter pests, and enhance the flavour of your crops.

• Herbs and Vegetables: Plant herbs like basil and parsley alongside vegetables to repel insects and improve the flavour of your produce.
• Flowers: Marigolds and nasturtiums can help deter pests like aphids and whiteflies while adding a splash of colour to your greenhouse.

Tip: Research the best companion plants for your specific crops to maximise the benefits.

Embrace Sustainable Practices

Sustainable gardening practices are essential for maintaining a healthy greenhouse environment and reducing your ecological footprint.

• Rainwater Harvesting: Collect rainwater to reduce your reliance on mains water and provide your plants with fresh, untreated water.
• Organic Practices: Use organic fertilisers and pest control methods to protect your plants and the environment.

Tip: Consider installing a compost bin to recycle garden waste and create your own organic fertiliser.

Stay Organised and Keep Records

Maintaining a thriving greenhouse requires careful planning and organisation. Keep detailed records of your planting schedules, fertilisation, and pest control activities.

• Garden Journal: Maintain a garden journal to track the performance of different plants and note any problems or successes.
• Label Plants: Clearly label all your plants, especially if growing different varieties, to avoid confusion and ensure proper care.

Tip: Regularly review your records to identify patterns and make necessary adjustments to your gardening practices.

Conclusion

Growing plants in a timber-framed polycarbonate greenhouse offers numerous benefits, from extending the growing season to providing a controlled environment for optimal plant growth. By choosing the right materials and following these tips, you can create a flourishing greenhouse garden that thrives year-round.

Remember, successful greenhouse gardening involves continuous learning and adaptation, so experiment, observe, and enjoy the process of cultivating a beautiful, productive garden. Happy gardening!