One of the most exciting times to have a backyard greenhouse is the fall season. As the temperatures start to move from scorching down to pleasantly crisp, your greenhouse still receives and captures enough warmth to keep growing those plants. It's a lovely respite where you can experience growing things all year round. However, one of the most important things to consider when choosing a greenhouse is how you will regulate the temperature inside, specifically how you will keep the temperature reasonably low in the summer and how you'll maintain a high enough temperature in the winter so that your plants thrive.
When Choosing Your Greenhouse, Notice Heat Features
One of the most popular ways to regulate the heat in your greenhouse is through a small window panel in the roof of the greenhouse. Depending on how high quality your greenhouse is, this could be everything from a panel that you can manually pop out to a cleverly designed window that can be cracked to allow heat to escape and equalize with the weather outside. These vents are a nice option for a long term method to keep your greenhouse at a good temperature. Another valuable feature is simply the door to your greenhouse; when you are out working on the plants, leaving the door open will help release summer stuffiness.
In the same way, your greenhouse has features for trapping heat in the winter. If the days start to get cooler, start to notice any "cold spots" inside the greenhouse, places where the weather stripping or another aspect of the greenhouse isn't holding heat ideally. Before the temperatures drop intensively, replace weather stripping or add insulating items; a simple rolled-up towel can make a difference. These modifications will only make the greenhouse oppressively warm over the summer, so consider making changes that are able to be undone, like the rolled up towel, after the winter passes.
Consider investing in shade blinds or netting that you can add to certain parts of the greenhouse if your area experiences a heat wave. Obviously, a big part of having a greenhouse is getting the full sun that will grow your plants, but for areas that are generally just tool storage or currently have partial-sun plants growing in them, a mesh shade net clipped over the window can really help to regulate the temperature. Just make sure that you remove them as soon as the most intense heat has passed.
If you enjoy automation projects, a simple and fun project can be to create a temperature-based system that automatically opens a roof vent in your greenhouse. Choose a temperature that is unlikely to be a problem for your plants to be the "tipping point," since even after the vent opens the temperature could rise a little while hot air escapes and the temperature equalizes. Professional greenhouses have many automated systems, from watering to fertilizing to fans, so a few small projects, like adding a fan that kicks in when your vent opens, might be both fun and useful.
When choosing greenhouse materials, look for double glazed panels or bubbled plastic that contains multiple layers; these materials will trap heat inside over the winter, making it possible to keep growing your spring and summer crops. Even with these materials, it can be hard to know exactly how cold it can get without damaging your chances of gardening success. Many gardeners keep a role of bubble wrap handy for covering any of those aforementioned cold-spots, creating a double layer of insulated material but still allowing the all important sunlight in.
Get the Most Warmth For Your Heating Dollar
While most gardeners would prefer not to have to heat their greenhouses, some areas mean that a little bit of winter heating is necessary in order to maintain growth. To keep heating to an absolute minimum, start with good insulation, and then invest in a good thermometer and a simple thermostat. With a thermostat, you can control when the heater comes on and allow it to run only until the plants are out of a danger zone. You can use special insulating cloth or fleece to protect plants on particularly cold nights, and by making sure you've planned ahead, you don't have to turn up the heater just because the outside temperatures are supposed to be very cold. Another good plan for your first few seasons in the greenhouse is to use as many cold hardy plants as you can in the greenhouse; even if they mostly need sunlight and warmth to thrive, picking the plants with the widest temperature tolerance will allow them to survive a tough night or two.
With these strategies, you can keep your greenhouse at a hospitable temperature for plants all year round, all while using as little excess energy as possible. Those winter vegetables will taste even sweeter for being grown at an unusual time!