Sun in the greenhouse: friend or foe?

Sunlight is the driving force behind every thriving greenhouse. Thanks to the sun, you create a unique microclimate where plants grow faster and your gardening season stretches far beyond spring. But how much sunlight does your greenhouse really need? And can it sometimes become... too much? Euro-Serre sheds some light on the matter. 

How much sunlight is ideal in a greenhouse?

For optimal plant growth, a greenhouse should receive 5 to 6 hours of direct sunlight per day. This is especially beneficial in spring and autumn. But in summer, temperatures can rise quickly, your greenhouse might turn into a sauna. And trust us: your plants aren’t fans of hot yoga.

What happens when it gets too hot?

Excessive heat causes stress in your plants. Leaves may scorch, soil dries out faster, and without proper airflow, diseases and fungi can thrive. A healthy growing environment depends on a careful balance of light, temperature, and ventilation.

How to keep the temperature under control

• Use a thermometer: monitor the temperature, and optionally the humidity, regularly. That way, you can act quickly when things heat up.

• Let your plants do the cooling: a full greenhouse heats up less quickly than an empty one. Plants absorb light and cool their surroundings by releasing moisture through their leaves.

• Choose the right orientation: place the ridge of your greenhouse north to south, with the entrance facing south. This allows for easy ventilation on hot days by simply opening the doors

• Ventilate effectively: ceeate airflow by opening windows and doors on opposite sides. Automatic window openers are a handy helper, especially during midday heat

• Add shade if needed: a shading screen can filter up to 60% of the sunlight and prevent your plants from burning. Some gardeners even paint parts of the glass with chalk-based whitewash for extra protection.

Is your greenhouse soaking up the sun? Try these sun-loving stars

• Tomatoes thrive in warmth and light, as long as they get enough water and air.
• Peppers and chillies follow the “the hotter, the better” rule.
• Aubergines are southern beauties that need plenty of sunlight to ripen well.
• Basil is a Mediterranean herb that grows fast in warmth and light.
• Cucumbers do exceptionally well in warm, humid conditions.

Sunlight is essential to your greenhouse’s success, but temperature control is just as important. With smart orientation, timely ventilation, and well-placed shade, you create the perfect setting for lush, healthy plant growth.

Each day in your greenhouse becomes a step closer to garden-grown happiness. Want more tips on where to place your greenhouse, how to maintain it, or why growing under glass is such a joy? Download our free magazine for more inspiration and advice.