How to Heat a Plastic Greenhouse?

Want to grow all year long without spending a vast sum of money? You must be tired and frustrated of spending dollars on your greenhouse and want to switch to something cost-effective.

A plastic greenhouse could be the solution to your problem. Build a plastic greenhouse without a second thought!

Do you know what makes a hoop house better than a glass greenhouse? Heat retention, that is! The material being used to build a plastic greenhouse can retain more heat than regular greenhouse kits.

This makes the house warmer, and you don’t even need tons of heaters or blah blah. We didn’t suggest you go completely without heaters, though. Then what did we suggest? Let’s dive in…

How to Heat a Plastic Greenhouse?

Because of their heat retention properties, plastic greenhouses are gaining popularity with time. But how can anybody make the best use of it without knowing the proper ways to heat up the house?

Kerosene or Paraffin Lanterns

kerosene lanterns for greenhouse

Yes, those old-fashioned metal lanterns I’m talking about. The ones that were used when there was no electricity; saved us at the darker hours.

But did you know that you could use them to heat up your plastic greenhouse? Well, a plastic greenhouse can retain heat decently. So the heat produced by lanterns can turn out to be a big source of heat at night.

If you’re using a small greenhouse, then one or multiple lanterns should keep the temperature a few degrees higher than ambient. You may increase the lantern amount as the greenhouse size increases.

I hope you’re aware of the fact that these lanterns leave moisture while heating up a greenhouse. So you better be cautious about this.

Make sure you’re leaving the front of the hothouse open on sunny days, along with turning off the lanterns.

Fan Heaters

fan heater in greenhouse

Can a plastic greenhouse ward off the frost without installing an electric heater in it? No matter how many arrangements you make to keep things warm, nothing can beat the effect an electric heater brings.

Do you know what the best greenhouse heater to balance the heat throughout the whole greenhouse is? Fan heaters, without a doubt.

There still remains the fear of overheating your plastic greenhouse by using an electric heater, right? Install a thermostat.

The advantage of using a fan heater is that it produces heat and spreads it equally throughout the whole room. Another thing is that it doesn’t leave moisture or humidity in the air, unlike other heaters. This makes it more prominent compared to others.


thermostat for greenhouse

I hope this is not the first time you’re reading about a thermostat. When you set up a greenhouse heater with it, it has the ability to stop the heater when the greenhouse reaches your desired temperature. And it is possible in your absence, which means turn the heater than just forget about it.

Then again, you may be worrying if the temperature drops too low after a while. Yes, it’s very harmful to tender plants. But a thermostat has the solution for this problem too.

When the room temperature drops too low, the thermostat feels it immediately and starts the heater to bring the temperature to a decent level.

Grow Lights

greenhouse grow lights

Did you know that some plants just love to get warmth coming from grow lights? Well, any summer-friendly plant would love this when being grown in winter.

Any greenhouse needs six hours of direct sunlight each day. Though any light that is emitting a decent amount of warmth can be used in your plastic greenhouse, lights that are made to heat a greenhouse are the best choice.

You can’t go for any grow light without a thought. That’s because different kinds of plants require different grow lights.

For example, if you are a winter grower and growing vegetables or herbs, fluorescent grow lights will do the job pretty nicely.

Fluorescent grow lights usually don’t emit too much heat to the plants. This is why growers can keep the lights close to the plants. They get lighter yet don’t get overheated, resulting in the plants growing faster.

Then comes the High-Pressure Sodium(HPS). This produces too much heat, and that’s why you have to keep the lights at a safe distance.

But along with heat, they produce plenty of moisture that calls for ventilation. If you’re a beginner, then this isn’t a safe option for you, and you should think about buying fluorescent bulbs instead.

There’re a lot more types of grow lights that you may find better for your circumstances. Make sure to research a little before setting up grow lights in your greenhouse.

Double Glazing

If one layer of the plastic wall can provide solid heat retention, then how better will it be to attach another layer? You must be worried about the costing right?

You better not be. There’re cheaper versions of plastic frames (e.g., polyethylene) waiting for you to pick them up from the store. So why delay the purchase?

You can attach these plastic frames to the inside walls of the plastic greenhouse. But before that, make sure you’re sealing the previously existing air drafts and repairing the broken panes.

Once you attach the plastic frames, your greenhouse temperature is going to increase by several degrees.

Another thing to be careful about is there shouldn’t be any gap between the two layers; otherwise, algae may start to develop. This will create obstacles for the greenhouse to receive heat from the sun.

Creating Compost Pile

greenhouse compost pile

We already know composting is very beneficial to our gardens and, of course, the planet earth. I mean, the earth is nothing without oxygen which comes from the greenery.

But did you know that you could make it more beneficial? Let me explain how…

Well, you may know already that compost releases heat while It’s not ordinary heat at all. In fact, it’s been used vigorously to heat up a plastic greenhouse (all kinds of greenhouses, though) for decades.

Yes, it can add a few degrees to the greenhouse temperature, which is tried and tested by growers all around the world. So don’t hesitate to bring the compost pile inside the greenhouse.

Terracotta Vase with Candles

terracotta vase with candles for heating greenhouse

Frankly, there are some conflicting opinions regarding this heating system. Some believe it works magically, while others say it’s not worth the penny, effort, and time. But if it actually was a failure, then how could it be some grower’s top favorite for decades?

Some scientists showed evidence on how magically it works on small houses, but you’d need dozens of tea candles in this regard. They also proved that this flower pot space heater system gives the same result even if you don’t use a flower pot. Sounds interesting?

Why do some growers still use candle heaters? Why don’t they light some candles alone?

Because the pot helps convert the heat from a particular mode of transfer to another mode. The newer model is way more useful than the former model. So this is all about it! Open flame heaters are dangerous and are able to wreak havoc in no time. So stay alert.

Insulate the North Wall

The north side of your greenhouse anyway receives the least amount of sunlight. You can utilize the north wall by attaching thermal insulation foil. How thermal insulation foil works is that it has reflecting properties; we all know that.

So the foil sheet reflects light and heat back to the house again. It also has the ability to hold in heat which is great for the plants. This way, insulation lets you double up the benefit of the sun.

Propane Heaters

greenhouse propane heater

Your greenhouse needs a consistent condition inside it, and you’d need a reliable energy source for that. There are electric, kerosene, paraffin, and propane heaters available to use in your greenhouse.

But the best amongst them all is propane heaters. No other heater can make the environment so lovely for the plants to grow.

This is why you’ll see commercial greenhouses using propane heaters all the time. Apart from the heat, your greenhouse needs enough co2 for its plants to thrive happily. Propane heaters do that job, too, pretty decently.

You’ve even got options to choose between a portable or an installed version of these heaters. With a propane heater, you don’t need to worry about power interruption because it doesn’t run on electricity.

Propane can easily be found at local gas stations, so you don’t have to stock it in large amounts.

Black Water Bottles

black water bottles in greenhouse

There must be some big water bottles lying over here and there in your house. Maybe you’re looking for an off-day to clean this unnecessary stuff. Hold on, please. These bottles can be used in heating your plastic greenhouse, trust me.

Gather some water bottles and paint them all black. You may know that black is the color that absorbs heat from the sun the most. Now fill these bottles with Water and spread them throughout the greenhouse.

The more bottles you use, the more heat you’re likely to get. Some people also use 55-gallon drums instead of water bottles. If you’ve got a large greenhouse, then go for the second option.

Don’t Knock the Snow Off

snow on a greenhouse

No, we didn’t go crazy.

Snow seriously will insulate your greenhouse if your grow house is covered with a heavy layer of snow. Take it as a gift from nature for you.

Snow is cold inherently and isn’t welcome indoors. But it doesn’t mean it’s harmful if left on top of the plant house. But if you ever feel that it’s hampering the sun rays to get in the glasshouse, then you may remove some part of it to create a way for the sun.

Then again, a really heavy layer has the ability to damage the greenhouse and make you count a huge loss. Heavy snowstorms usually leave big blankets of snow everywhere, including greenhouses.

Stay alert that while and try to get rid of the extra snow that’s creating pressure on the grow house.

Use a Heat Mat

greenhouse heat mat

It’s important to keep the floor warm like the environment, especially when your plants are at the germination stage.

Using a heat mat is going to help your seedlings like nothing else. This is wherein the whole greenhouse and you need warmth more.

This way, you can start growing early without a hindrance. The seedlings need warm soil to germinate fast and properly. Placing your seedling trays over a heat mat will keep the soil in the plant pot very warm and cozy.

Make sure you’re connecting it to the power to start heating the mat. Only then will the plants grow out healthy and happy. You’ll be able to produce fruits or vegetables way before your neighbor does.

Final Words

A plastic greenhouse is nothing but a regular greenhouse built with plastic material. Though a plastic greenhouse is better at heat retention than a glasshouse, you still need some methods to heat it up. Some are costly, while the others come for free.

You may combine these two together to create a better growing environment for your plants. Remember, nothing comes without making an effort.

You can check these heating methods given above and find out which ones seem easy for you. Go for multiple heaters if yours is a large or commercial greenhouse.