Our head gardener Emma shows you how to tackle common issues under glass

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I'm sure most gardeners with a greenhouse imagine themselves pottering away among ripe tomatoes, fresh chillies and maybe an exotic or two thrown in!

Growing under glass offers you a controlled environment: the plants are protected from the worst of the British weather; there’s an even distribution of light and a potential reduction in pests. A glasshouse will also help to extend the growing season, allowing seeds to be sown earlier and harvesting to go through to the autumn months.

However, it’s easy for things to go awry in your greenhouse so, here, I share some quick fixes to help get the balance right.

1. Fluctuating temperatures 🔗

Plants need consistent temperatures, but glasshouses tend to overheat, particularly around May, when temperatures can spike in the daytime and drop at night. This leads to scorch, wilt, and pests like red spider mite.

Solution: Get a thermometer so you can monitor the temperatures, particularly at night. Open the vents if the temperature reaches 18C - and if it gets above 25, open the doors as well. If the temperature is due to drop, cover susceptible plants or invest in a portable heater to keep a consistent temperature.

2. Damp conditions 🔗

Overwatering is probably the most common issue; too much water leads to damping off, fungus, mold, and mildew. Conversely, there’s often very little shade in greenhouses, and coupled with glass this can lead to scorching, leggy plants and general overheating in late spring and summer.

Solution: Water first thing in the morning and only if the first 2cm is dry. Use drip irrigation where possible and don’t water overhead onto the leaves. At Garden Organic, we shade our glasshouse by growing quick climbing annuals such as sunflowers and Black-Eyed Susan to keep the sun off. You can use netting or specialist paint, but the more diversity in your space the healthier the ecosystem.

Try to keep the area clean and tidy and create a natural ecosystem. Damping down surfaces to raise the humidity and cool the air are all good practices in disease prevention.

3. Lack of natural elements 🔗

A greenhouse will shelter plants – but it will also restrict rain, wind, and beneficials to mop up pests, including birds, as well as pollinators, which can help with pollination and fruit formation. A lack of air and overcrowding can lead to diseases.

Solution: Open the vents to allow for creatures to visit and help with pollination, otherwise hand pollinate where possible. A fan or a gentle shake can help spread pollen for those requiring wind. Auto vents and planting with appropriate spacing will ensure air keeps moving to prevent fungal diseases.

Monitoring your plants is crucial. Lift the leaves, inspect crevices to catch any unwanted visitors quickly, or blast pests such as aphids with water. Also consider growing disease resistant varieties, rotating your crops, and using biological controls.