My Greenhouse Is Too Hot

My Greenhouse Is Too Hot! How To Reduce The Heat?

In Temperature by Ana M

Growing plants in a greenhouse is fascinating and challenging at the same time. It is more time consuming than growing plants outdoors. Mainly because outdoor plants rely on natural elements for their needs. In a greenhouse you are in charge to provide fruits and vegetables with water, warmth, humidity and food.

The first basic need is water. It is not only about forgetting to water a plant. Most of them actually suffer from overwatering as these plants need a resting period. Learn how to water plants in a greenhouse and what watering systems you can use.

But today we are going to talk about temperature in a greenhouse. We will find out why your greenhouse is too hot and what actually grows well in higher temperatures.

How hot should a greenhouse be?

For most greenhouse and conservatory plants the temperature range of 55°-75°F (13°-24°C) is hot enough for active healthy growth. That is comfortable temperature for seedlings and mature plants. However, you should keep you greenhouse hotter than this for germinating seeds. Also, keep in mind that mature plants can tolerate fluctuations outside the comfort range rather than young plants.

greenhouse is too hot

It is important to understand that minimum temperature requirement is for the plant to flourish. Even though most plant types can grow at temperatures below the stated minimum, this tolerance is not large. That it why you should not mix heat loving plants with hardy plants.

So, what to do if you want to have a mixed collection? Simply divide a section of the greenhouse with transparent material for warm loving plants. You can also line the sides and roof with bubble wrap to trap the heat. Place a heater in the warm section. Use this guide on the cheapest greenhouse heaters to run.

Does greenhouse get too hot in summer?

The temperature in a greenhouse rises in late April or May. In summer months greenhouse can get too hot with temperatures over 85°-90°F (29°-32°C). These temperatures can result in fatal damage to plants. When plants get too hot in a greenhouse the lower leaves start to wilt and edges turn brown.

Moreover, when it is too hot plant’s bottom leaves fall and plant growth is spindly. Also, flowers are short-lived and start to fall off. Dry heat is more dangerous for plants that moist heat. You must keep the day-time temperature fairly constant during growing season.

What grows well in a hot greenhouse?

You can grow a variety of warm loving plants in summer when a greenhouse is hot. Ideal temperature for Chrysanthemum is 60.8°F while Cucumber and Tomatoes thrive in 65°-68°F. Cacti and melon grow well in a hot greenhouse as they need a temperature of 71.6°F and 75.2°F respectively.

What grows well in a hot greenhouse?

How to reduce the heat in a greenhouse?

The best way to reduce heat in a hot greenhouse is damping down. All you need to do is to use hose pipe to wet the floor and benches. Once a day is enough in April-May but wet surfaces as often as three times a day in midsummer. Oh hot days you need to mist plant leaves with water.

When damping down water evaporates and the temperature in a greenhouse lowers. It also increases air humidity resulting in reduced water loss through plant leaves. This leads to less frequent watering, however, moisture-loving plants are still able to survive.

Source – Gardener’s World

Moreover, damping down helps to control greenhouse pests. For example, some pests like red spider mite and thrips live in dry air. To lower the temperature in a greenhouse, you need to damp down the floor and mist the plants when the structure is adequately ventilated.

However, the benefits of manually damping down the floor and benches are temporarily on a hot day with all the vents open. If you are growing professionally, you can invest in electronic humidifier which provides water vapor continuously.

If you are a hobby gardener, you can lay down capillary matting on the staging to create a continually damp area. Even though you are damping down, misting and ventilating, greenhouse is till hot? Let’s find out why does greenhouse get hot.

How does a greenhouse work?

A greenhouse traps radiant heat from the sun, so the sun rays pass through the greenhouse glazing. The greenhouse plants and objects inside the structure absorb the sunlight and convert it to heat. Then air, evaporating water and objects inside the greenhouse store the heat. This heat is unable to leave the structure, as a result, it stays inside the greenhouse and keeps it warm.

African Violet

So, even though a greenhouse should be in full sun, it is essential to apply some sort of shading to maintain temperature at or above 75°F. A direct summer sunshine can burn Begonia, African Violet and Gloxinia plants. There are four simple ways to shade a greenhouse.

If you have a small greenhouse, it can be enough to place small plants in the shade of larger ones. Moreover, you can place a newspaper over seedlings, rooted cuttings and plants with delicate leaves. However, if you live in sunny climates or high altitude areas, it might not be enough, so I can recommend using a shade cloth.

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