Why are all My Greenhouse Plants Stressed in Summer?

Summer Heat Can Make Managing Your Greenhouse Impossible

One of the more common complaints I receive when talking to folks about managing their greenhouses is how poorly many of their plants are doing during the hot summer months.

Did you know that once temperatures get too hot outside, the temperature in your greenhouse is going to get even hotter? And there is a point at which no amount of additional cooling is going to lower the temperature enough. Not only that, but the hot and humid conditions created in summer greenhouses are the perfect breeding ground for many tough pests, such as scale.

In fact, if it's warm where you live and you currently have citrus plants in your greenhouse, I'll bet you good money you're struggling with a scale infestation! It's a classic.

But Isn't my Greenhouse Supposed to be Warm?

To a point, yes. It's very easy during summer months for greenhouses to heat up far too much, which causes a lot of plant stress and even plant death.

Ultimately, it's easier to heat a greenhouse than it is to cool it, especially in hot climates. The ideal average best daytime temperature range for your summer greenhouse is between 80-85F (27-29C). If it's 90F (32C) outside, you can bet the internal temperature of your greenhouse is going to be hotter. And once the internal temperature of your greenhouse exceeds 90F, your plants will struggle and pests can be overwhelming. Controlling your internal greenhouse temperature once it's that hot outside is also challenging, even if you are running cooling units.

There are many different appropriate temperature ranges inside a greenhouse depending on what you are growing. In my new book "Home Greenhouse Revival" I break down seven different categories and temperature ranges you can use to guide you when deciding on what type of greenhouse to build or install, and what target temperatures benefit different plants.

So How do I Keep my Greenhouse Cooler in Summer?

Keeping your greenhouse cooler in summer typically involves adding sun-blocking elements such as shade cloth or whitewash on your greenhouse, in addition to running cooling units. Yes, this will block a lot of the radiant energy (sunlight) coming in to the greenhouse, but it will also help reduce internal temperatures and help your cooling units do a better job of moderating the temperature.

OR...you just may need to move your plants outdoors for the summer if you live in a very hot climate. And guess what? That's OK. For some of you, depending on your climate, you will be able to grow plants inside your greenhouse year-round. But for those of you in very hot climates, it's OK to know your greenhouse's limit and move plants outdoors if that provides a better growing environment.

Dig Deeper

If you'd love to dig deeper and learn all about managing a greenhouse environment effectively, including all the most effective cooling strategies, check out my new book "Home Greenhouse Revival"