Ahhh… Summer’s here! Icecream, fresh mint iced tea, sunbathing and water games… Summer is a great season for salads, fruit and fresh spices! The exotic temperatures are perfect for growing tomatoes, oranges, lemons and sweet potatoes. Whether you’re growing outside or in a greenhouse, summer is the time to spend harvesting and maintaining your crops.
When you have a greenhouse, summer also comes with a little bit of a warning: be careful your greenhouse doesn’t get too hot! Especially during extremely warm summer days, the temperature in your greenhouse can increase rapidly. So, how do you protect your plants during a heatwave or a hot summer?
1. Monitor the temperature
Makes sense right? You can’t know your greenhouse is too hot when you don’t know what the temperature is. Whether you want to install a basic thermometer inside your greenhouse that you can check manually every couple of days or you’re a little bit of a tech freak and own a full-blown weather station that sends live data to your phone, a greenhouse thermometer is a necessary accessory when you want to manage the heat in your greenhouse.
So what temperature is too hot for your greenhouse? The general rule of thumb is that anything above 90 degrees Fahrenheit (or 32 degrees Celsius) is too hot. When your greenhouse temperature rises above 90 degrees, we advise you to take action to lower the temperature. The perfect temperature for a greenhouse during spring and summer is about 80 to 85 degrees Fahrenheit or 26 to 29 degrees Celsius.
Take a look at our greenhouse thermometer article to learn more!
Ventilating your greenhouse is a good idea all year long, but is necessary during summer. Getting fresh air to your plants and preventing humidity to rise, will help your plants grow. Most greenhouses have openable windows and doors. You can open your windows and doors manually when you see the temperature increasing to let the fresh air in. This works perfectly, just check your thermometer and ventilate accordingly.
The downside of manually opening your winds is that you need to be near your greenhouse to intervene when necessary. To avoid this issue, you can install a hydraulic system that opens the windows automatically when the temperature gets too high. These are not too expensive (they start at 75 dollars) and are easy to install. Some of the more high-end greenhouses even come with a ventilation system included. For us, the automatic window openers give us peace of mind, as we know our plants won’t be burning up when it gets hot outside.
When the ‘natural’ ventilation isn’t sufficient, you can add a fan for extra ventilation. Ideally, you place your fan near the ground and close to the door, to pull in as much cool air as possible.
3. Use shade cloths
Sometimes ventilation alone is not sufficient to prevent your greenhouse from overheating. Especially in very sunny areas or during a heatwave with bright sun all day long, adding a shade cloth is a good idea. Shade cloths come in many shapes, sizes and materials. You can either go for woven or knitted shade cloths and the density will differ. The higher the density, the higher the amount of protection and thus the lower the amount of sun and light coming in.
Take a look at the best shade cloths!
4. Some additional tips
When you install your greenhouse, think long and hard about the best place in your backyard. When you live in sunny California, you may want to install your greenhouse partially in the shadow or close to a tree that can provide some shadow during summer. When you live in the north, you want to catch as many sun rays as possible to be able to grow during spring and fall.
Rotate your crops. Make sure you focus on heat-loving crops during summer. Tomatoes, sweet potatoes, citrus fruits, peppers and eggplants… These plants will continue to produce in a warm greenhouse, as long as they find enough moisture in the soil.
During a hot summer day, you want to keep the soil extra moist. Your plants will be thirsty and need enough water to survive.
There we go… You’re all set to protect your plants from any heatwave and enjoy your homegrown vegetables all summer long!