When the weather turns cold, your greenhouse isn’t going to be as warm as it was during summer months. You will need a way to keep the winter temperatures out of your greenhouse if you want your plants to survive. Using a utility heater for this purpose isn’t difficult, but will dry out your plants faster. Monitor their water needs closely until you are used to your new heater.
Utility heaters a small metal or ceramic devices that are plugged in to produce heat. They are reliable, and many of the safer models come with a tip-over sensor that will turn the heater off if it falls from the upright position. This feature will prevent fires, and is worth the extra money.

Proper Heater Size

Unlike fuel powered heaters, utility heaters have their heat output measured by watts. If you plan to use a utility heater in your greenhouse, you are going to have to first figure out what size heater you will need to properly heat your unit. Keep in mind that it isn’t the physical size of the heater that matters, but rather the amount of watts it is capable of putting out.
To determine how many watts your greenhouse will need, you first need to determine how many BTUs your greenhouse would need to keep it warm in the winter. This is done by using the following formula. Keep in mind that the * symbol means to multiply.

Square feet of greenhouse * annual temperature difference * heat loss value of greenhouse covering.

Once you have determined the BTU amount your greenhouse would need to be heated, you can convert that number into watts easily.

BTU * 0.000293

This formula will tell you how many watts you need for your greenhouse to be kept warm. When you purchase a heater, you probably won’t be able to match your needed watt output exactly. You will want to aim to go over your needed watts amount, but not by much. There is no reason to run a heater that is too powerful, as it will waste electricity and may keep your plants too hot.

Electrical Options

Utility heaters run on electricity. This means that in order to use one, your greenhouse needs to have electricity run to it. If yours already does, then this is no problem. If it doesn’t, then you will need to figure out how to get electricity to your greenhouse.
Your first option is to have a certified electrician run electrical lines to your greenhouse. This is by far the safest option, but can be expensive. You will need to have multiple outlets installed to power everything that is needed, and the greenhouse may require its own circuit.
If your greenhouse is close enough to your home, you might be able to power it using extension cords. The extension cords being discussed are the heavy duty ones that specifically state they are rated for outdoor use. You will want one that is brightly colored so that you can see it to reduce tripping risks, and it is vital that the single cord be long enough to reach all the way into your greenhouse. The plug areas are not water tight, and pose a danger if out in the elements.

Heater Options

You can purchase a single utility heater for your greenhouse that slightly exceeds your watts usage needed. Your other option is to purchase two or more units, but make certain that their combined watts output adds up to the number that you need.
Regardless of your choice, you will need fans to keep the air in your greenhouse circulating. The heater alone will create a zone effect, with plants near the heater becoming too hot and those far away being too cold. If you choose a single heater, you will need more fans than if you choose multiple heaters. These fans should be set up to blow the air around your greenhouse at plant level, with additional fans placed near the ceiling to blow rising heat back down toward your plants.

Using the Heater

Read the instructions with your heater(s) carefully. Each heater requires a certain amount of room around it to prevent fire hazards. Place your heater(s) accordingly on solid surfaces and plug them in. Turn them on and monitor your greenhouse to make certain you are getting your desired heat range.
Whitney Segura is a web content copyrighter for Our Crazy Deals, one of the leading suppliers of greenhouse and gardening supplies within the United States of America. Visit Our Crazy Deals online, to find more information about using a utility greenhouse heater, in your garden.