Updated at: 23-04-2022 - By: Sienna Lewis

To be able to control the temperature in a small greenhouse, you’ll need to put in a lot of time and effort. We’ve covered a lot of ground on greenhouse temperature in the past, but now it’s time to cover some new ground.

Why You Might Want A Small Greenhouse?

Even though greenhouses aren’t mandatory for most cold climate growers, they can be a huge asset for those who do.

In chilly areas, the greenhouse offers the grower two important advantages.

The greenhouse’s most valuable feature is that it allows you to plant your garden seeds outside before it’s safe to do so due to frost.

How to Regulate the Temperature in a Greenhouse? - Ready To DIY

To gain an extra two weeks of growing time, most basic greenhouses will raise your frost zone by an entire zone.

It’s possible to start many of your garden plants a month or more before your normal final frost in a heated greenhouse.

The second most important function of a greenhouse is to help warm-weather crops thrive. Though useful, it isn’t as as important as freeing up your indoor grow area in the early spring in chilly climates.

The primary purpose of this essay will be discussed in detail. Starting some of your garden early in the season, even if it isn’t safe to do so.

Inventing A Small Greenhouse Solution

People may not have a greenhouse for a variety of reasons. It is possible that you are a tenant or a resident of an apartment complex. Perhaps there isn’t enough room in your home. Alternatively, you may not have the money, time, or expertise to build or purchase one.

We didn’t have a greenhouse, we couldn’t build one, and we desperately needed anything to help us grow a large number of plants.

So, in a way, we pioneered something that hasn’t been chronicled all that extensively. As a result, it has become a vital part of our cold-climate farming strategy.

Your main takeaway from reading this post? A greenhouse doesn’t need to be a permanent construction to grow vegetables. It might be a movable construction that is erected and dismantled according to the changing of the seasons.

Building The Small Temperature Controlled Greenhouse For Garden Starts

We set out to see if we could regulate the temperature of an Amazon greenhouse we bought for a reasonable price.

We came up with the following strategy:

  • Greenhouse that is low-cost and compact
  • Temperature controller
  • Space heaters that are small and inexpensive
  • 6-inch clip-on fan for individual use

A few of affordable Gardman Greenhouses were found on Amazon for a reasonable price. They are normally $40, but we were able to get them for $25 because they were on sale late in the season.

The front of the box has a zip-up access that permits watering and venting of the plants. It has four shelves to save vertical space.

With a few zip ties and anchors, we believe this “cheap” greenhouse will last at least a few seasons. (For the most recent information, see the section at the bottom of this post.)

It’s probably a given that we dismantle this greenhouse throughout the winter. This style of greenhouse isn’t built to withstand the harsh winters of Interior Alaska!

The Thermal Reality Of All Greenhouses

Temperature is always going to be a challenge in any greenhouse, hoop house, or cold frame.

In the absence of incoming heat, the greenhouse’s temperature can readily drop to that of the surrounding air. Your plants will freeze if the temperature outside is below freezing.

Hardy cold weather crops are the best able to survive good freezing.

A greenhouse, by design, is able to retain a significant amount of heat. Lots and lots of hot air. On a good 60-degree day, it’s not uncommon for a greenhouse or cold frame to reach 120 degrees or higher.

Ventilation is always required in a greenhouse, whether manually or by some kind of automated mechanism.

We don’t always have the luxury of time to ensure that our greenhouse is adequately ventilated or insulated, depending on the weather. We wanted to be able to control both heat and cooling automatically.

A large sum of money was not something we wanted to invest in such a short-lived greenhouse project, either. The main idea was to keep the price low.

How Do You Regulate And Balance The Greenhouse Temperature

It doesn’t matter how big or little your greenhouses are; water can be used to cool them down.

How Water Cooling Works

It’s possible to manually spray the greenhouse’s interior with hot water to freshen it up. Misting and fogging are also useful in removing the warm air, as water evaporates at a greater temperature when it is applied in a finer spray, and this will also help to keep the plants from drying out.

Ventilating With Fans

The greenhouse can then be ventilated with the aid of fans. Did you know that they serve a dual purpose by directing hotter air outside and bringing cooler air into the greenhouse when they’re not in use? The location of the greenhouse’s fans will have a considerable impact on the efficiency of the greenhouse for the gardener.

They should not be placed on the ground or on the roof, but rather in the estimated five to six feet high just in front of your greenhouse’s vent systems to encourage air flow.

To provide a semi-automated cooling system, ventilation fans will be connected to the thermostat.

The Use Of Proper Shade

Keep in mind, as well, that the use of correct shading in your greenhouses will help keep the temperature stable. By lowering the amount of solar energy that reaches the plastic sheet or glass, this is made possible. Your structure may be covered in a variety of greenhouse forms, including vines that are leafy and the compound used for shading.

How Do You Keep The Mini Greenhouse Cool?

Ventilation is the answer. Side vents, louvered roof vents, and the greenhouse door all help to circulate cool air through your greenhouse, which in turn helps to cool down the hot plants within.

As a general guideline, the vents should cover around one-fifth of your floor surface in order to provide a complete air exchange every two minutes. As a gardener, it’s important to do your research and always be open to new ideas and information.

How to keep your greenhouse from getting too hot? – Greenhouse Hunt

What Temperature Is Touted Too Cold For The Greenhouse?

This is a fascinating subject, because your greenhouse may not be able to handle temperatures below a certain point. And all of this information is necessary for figuring out how to keep a small greenhouse at a comfortable temperature.

There are a few things to keep in mind when you’re using your greenhouse. When it comes to using this in a given year, it might be both ways. Maintaining the greenhouse at a temperature of 13 degrees Celsius or higher is the bare minimum.

It is also important to maintain a temperature of seven to eight degrees Celsius in the cool house. In the daytime, the temperature should never go below 32 degrees Fahrenheit.

How Do You Heat Your Greenhouse In The Most Affordable Way?

Take note of the fact that the expense of greenhouse heating, especially in the winter, may outweigh the savings you can save by growing your own food.

In order to heat the greenhouse without using electricity, there are a number of cost-effective options. The use of bales of hay or straw, followed by the heating of old oil barrels, dust bins, and bunny hutches, is one option. If you continue reading, you can find out more about this.

The gardener should be able to make changes to the greenhouse’s insulation in order to reduce the expense of heating the greenhouse in the winter. The following are a few of the things you’ll need:

  • Cardboard
  • Wrap in bubbles
  • a variety of straws

Keep The Greenhouse Organized

One of the most important things to remember is to maintain the greenhouse neat and tidy. Clean plastic is preferable to glass, but if the greenhouse overlaps in such a way that it receives full sun, use plastic.

Free Heating Of The Greenhouse

It’s also worth considering the lean-to greenhouse, which makes advantage of the heat that escapes via your house’s windows and doors. For this reason, you should make the most of the greenhouse’s free heating.

Greenhouse Built On Wood

In addition to being better at retaining heat, constructions composed of wood or brick can also do so. Straw bales can be used against the bottom windows of the house to solve this problem.

Sealed Gaps

However, the gardener will be able to notice any leaking door seals or ventilators because of this method, which keeps heat from escaping around doors and windows.

Which Conditions Affect Growth in a Greenhouse?

Several factors influence the output of your greenhouse, as previously indicated. You must guarantee that all of them are suitable for your crops in order to get a good harvest. Here are the details:

  • Temperature. Ventilation and sunlight are the two most important factors in determining the temperature of your greenhouse. To store heat, your greenhouse must be able to capture as much sunlight as possible. In order to maintain a comfortable temperature in the greenhouse without allowing it to become overheated, ventilation is a need. Temperature can be improved by opening the windows, doors, roof vents, or even turning on the air conditioner.
  • Humidity. Humidity is also a significant impact. To put it another way: Plant leaves produce wet air that fills the greenhouse, making it a lot drier. Humidity, on the other hand, is a difficult thing to manage. A dehumidifier may be necessary, but you may also try opening the doors and vents.
  • Seasons. To grow plants in a greenhouse, you have to convince them that it’s springtime. Winter, or the season opposite to the plant’s growth season, is the most difficult time to do this. However, replacing the sun’s rays with artificial light is a viable option for controlling the environment’s temperature and humidity.
  • Ground. This may be the most difficult adjustment to make, and it will take a lot of time and effort. To ensure that the soil is in the best possible condition for growth, you must keep an eye on the moisture levels and pH levels.

Tips for Regulating Temperature in a Greenhouse

One of the most critical aspects of providing plants with a healthy habitat is controlling the temperature. In the summer, you want to keep it tolerable, and in the winter, you want it to be warm enough. In autumn and spring, when temperatures are mild and there is enough sunlight, it is considerably easier.

Buying a greenhouse with vents in the roof that you can open or close is an excellent approach to control the greenhouse’s temperature. You can simply lower the temperature inside these sorts of green homes during hot weather by opening a ventilation grate.

You can open manual vents yourself, or you can have automated vents open for you. Greenhouse doors can also be used to bring in some cooler air if the temperature rises too high in the greenhouse during the day. Opening the doors of your greenhouse will make it more convenient to operate in, especially during the summer.

It is imperative that the greenhouse has characteristics that keep heat from escaping and keep heat from escaping during the winter. Among other options, seek for chilly corners of your greenhouse where a breeze blows. This signifies that the greenhouse needs to be insulated because the heat is escaping. Even a simple rug or a towel can make a great impact in keeping the heat in, even if it’s not made of quality materials.

Consider purchasing a sun shade for your plants if you live in a region prone to heat waves during the summer. Aiming for as much sun as possible can lead to dehydration. When it comes to plants that require a mix of sun and shade, this is especially crucial to keep in mind.

Once the extreme heat has passed, be sure to eliminate any shady areas and provide plenty of direct sunlight for your plants.

It’s possible to automate most of these things, but it will cost money. However, if you have a large greenhouse, you may be able to achieve this without putting a dint in your wallet.

Insulation Options for the Winter

This section focuses on winter temperature alternatives, which are a little trickier, but can be accomplished with a few simple adjustments. There are, of course, more advanced options, but these work just as well.

When it comes to keeping the greenhouse warm in the dead of winter, though, it’s a very different scenario. Your plants have to thrive despite the frigid conditions, which include snow and freezing winds.

Insulating your greenhouse is one of the best things you can do for your plants in this situation.

Double-glazed panels in your greenhouse should be sufficient to support it. Bubbled plastic versions are also available. Both are excellent in insulating the house from the cold. In addition, it is useful during the hot months.

If you want to ensure that you have protection even on the coldest days, you can keep a roll of bubble wrap accessible and put it where it’s needed. To keep the heat and light in, bubble wrap is a fantastic option.

While heating a greenhouse isn’t the ideal solution, it is one that can be considered. The colder parts of your greenhouse will necessitate additional heating. Insulation can help you save money on your heating bill by reducing your energy use. The heating and when it is turned on could be controlled by a thermostat.

Another option is to think ahead and only plant hardy varieties that won’t succumb to the cold.

Common Greenhouse Problems and Solutions - Dave's Garden

Other Tools in Temperature Control

Additionally, there are a number of different devices that can be used to regulate the greenhouse’s temperature. You could improve your productivity and increase the yield of your crops even further if you used them. Some examples are as follows:

  • It’s time to get out the thermometer. You can keep track of the temperature in your greenhouse with the help of a dependable thermometer. Of course, there are many different types of thermometers to pick from, such as humidity thermometers, memory thermometers, standard thermometers, and so on.
  • Fanatic. You’ll be able to get better ventilation this way. They will reduce the temperature inside your greenhouse. A bit of fresh air will help your plants grow at optimal rates, and you’ll be able to reduce humidity as well. Fans also prevent diseases from spreading around your greenhouse.
  • A follower. As a result, you’ll have more control over the flow of air. Your greenhouse’s temperature will be lowered as a result of their presence. You’ll be able to lower the humidity and help your plants develop at their best rates by just opening the windows a crack. Using fans in your greenhouse can also help reduce the spread of illness.

Setting Up Temperature Control Of The Small Greenhouse

A devotee. As a result, you’ll be able to enjoy better ventilation. They’ll help to cool things down in your greenhouse. With a little amount of fresh air, your plants will develop faster and the humidity will be reduced. Keep your greenhouse disease-free by using fans.

I’m not confident that a $25 greenhouse will be able to keep the temperature high enough to avoid a disaster in the event of frigid temperatures.

The plan was to utilize a tiny space heater to keep the greenhouse warm in the case of a frost. Then again, we wanted to conserve energy and only turn on the heater when it was absolutely necessary. We only needed to keep the temperature at a certain level all the time.

A new controller has arrived: the Inkbird ITC-308. It’s a great little gadget that provides inexpensive control over both high and low temperatures.

The temperature is constantly monitored by a temperature probe in this temperature controller. A heater can be activated if the greenhouse becomes too chilly. To help disperse the heat, it activates a fan in the room.

Figuring Out The Small Greenhouse Heating & Cooling

The goal here isn’t to warm up a vast space. 12 cubic feet is the most this greenhouse can hold.

If the temperature drops below 40 degrees Fahrenheit in late April and early May, we just need to heat that area by 10 to 15 degrees.

It felt like a simple task to meet these modest needs. I couldn’t figure out how to get the information I wanted.

How many BTU’s are required to meet the stated heating requirements for this space??

In order to better understand greenhouse heating requirements, I decided to learn more about BTUs. At the very least, this program will be able to make use of it.

Initially, it felt as though I was embarking on an engineering project. Actually, you can utilize online calculators to figure it out or double-check your work with a reasonable degree of accuracy, it turns out.

When I discovered that a space heater with a relatively low power would suffice for my needs, I was overjoyed.

Each of the Lasko 100 “MyHeat” 200 watt space heaters cost under $15, making them an excellent choice for this application.

For $10 a month, we could run it for eight hours a day for eight days a week. It’s very likely that it’ll be much, much less.

We used a little 6-inch personal fan to help with the ventilation, and it worked out great.

On days when we expect the greenhouse to get hot, all we have to do is position the fan at the greenhouse zipper and crack the zipper door.

So far, the 6 inch fan hasn’t caused any issues even when the greenhouse temperature reaches 90 degrees or more.

Configuring The Temperature Controller For Optimal Temperatures

In order to use the temperature controller properly, we must make the following adjustments:

  • Setting the temperature
  • Differential in Heating
  • Differential Cooling

It’s easy to see that the temperature set value is the intended temperature.

The difference between the target temperature and the actual temperature is known as the disparity.

We need the thermostat to activate the heater at 40 degrees Fahrenheit and the fan at 75 degrees Fahrenheit, respectively. This is how we went about it:

  • 45 degrees Fahrenheit is the temperature setting.
  • Thirty degrees Fahrenheit of cooling difference.
  • Temperature Difference: 5 degrees F.

It will begin to heat the room at 40 degrees, which is five degrees below the predetermined temperature. The heater will be turned off when the temperature reaches 45 degrees.

Because heat rises, the heater insulates the entire greenhouse. Place a blanket on top of the greenhouse to assist trap heat from the heater, as well, according to our experimentation.

At 75 degrees, or 30 degrees above the temperature set threshold, the fan will activate for cooling purposes. The only thing we need to do is open the greenhouse door on days when the fan is expected to run. Those are the days when the sun is out and the temperature is at least 50 degrees.

Using a single temperature set point is the “poor” element of these inexpensive temperature controls.

The fan’s goal is to bring the greenhouse’s temperature down to 45 degrees Fahrenheit using these settings. That’s difficult on a hot day, so the fan will keep running until the evening, when the temperature begins to drop.

Using two separate temperature controls for heating and cooling is the only way to avoid this problem.

It’s possible that your unique configuration differs from ours. There isn’t a single setting that will work perfectly for them, but there are a variety of options.

Scaling This Up To A Real Greenhouse:

Scaling this concept up to a larger greenhouse will have an impact on several aspects. In a small greenhouse, the same principles apply. How we managed the greenhouse’s temperature can be found here.

Heating the greenhouse is the first step. Using the heater described above in a large greenhouse will do little or nothing. Determine the BTUs needed for your space, and then buy a heater that is rated for that size.

Electricity and fuel-based systems can be very expensive for this purpose. A 110V electric heater won’t do the trick in many greenhouses.

Another fan or maybe several would be used for cooling purposes. I’d recommend at least one standard 16-inch inline fan for most medium-sized greenhouse projects.

You can use an online calculator to figure out how much CFM (cubic feet per minute) you’ll need for your greenhouse.

Somewhere in the greenhouse, these fans would be mounted on a wall. Adding a vent to the greenhouse’s opposite wall would likewise enable fresh air into the space.

The fan’s CFM can be used to determine the appropriate vent size. Automatically closing shutters would be included in both designs.

It may be a better idea to utilize a smaller greenhouse, like the one we’ve discussed, to raise your seedlings. This will allow you to cultivate a substantial amount of summer veggies in the larger greenhouse.

Because it saves a lot of money on heating expenditures, we do it this way.

An even better option is to build a tiny greenhouse inside the larger one you already have. Two levels of greenhouse protection would be provided as a result of this method Almost a full growing zone benefits from each additional layer of greenhouse protection!

Even 4-6 weeks before your normal last frost, there would be relatively little heating required. It’s important to keep in mind that two of these temperature control systems are required because each greenhouse must be ventilated.

Additional Notes On Small Greenhouse Temperature Control

With this configuration, there are a few obvious safety measures.

Cords and other impediments should be maintained to a minimum to maximize the heater’s output. Despite its modest output, you should take precautions to avoid having it pointed directly at the greenhouse’s plastic exterior or any other combustible materials.

Where to position your greenhouse? | Thompson & Morgan

When watering your plants, keep in mind that water and electronics don’t mix. Better still, transfer all of the plants outside so that they may be watered from the ground.

We use a Bluetooth thermometer to keep tabs on the lowest and highest low and high temperatures. Being able to detect when we’re starting to strain our heater’s limitations or when the fan has to be adjusted a touch is a comfort.

We’ve found that if you’re trying to get your plants outside as soon as possible before the last frost, you’ll need to provide them with extra heat. During April, we install two of the 300 watt heaters, allowing us to heat against temperatures well below zero degrees.

Final Thoughts On Small Greenhouse Temperature Control

We’ve been using this combination for several years now and are really satisfied with it. Everything went according to plan for some of our transplants’ migrations

This low-cost option has performed as expected. Even in the low twenties, we haven’t had any issues heating the house. However, the cost of running that heater isn’t prohibitive. It’s not racking up a huge electric bill, and that gives us a sense of security.

I was able to put up two thermostatically controlled tiny greenhouse setups that had more than enough area for our moderately sized transplant operation with a budget of about $100.

As far as our yard is concerned, this was a big success.

Longevity Updates For Our Small Greenhouse Temperature Controlled System!

For the past two years, we’ve been using this setup, and it’s worked out great. Though they were exposed to sub-zero temperatures throughout winter, greenhouses have held up fairly well. In the month of May, when growing space is at a premium, having a place to house plants besides the indoor grow room is a tremendous asset. This is where we prefer to put our cool-season plants, while keeping our warm-season plants in the house for optimal safety and security. As a result, we’ve been able to delay the purchase of a production greenhouse, which is still on our agenda.

Longevity Update 2: Well, for $25, you wouldn’t expect it to last forever. The zipper seam on one of the greenhouses tore in the third year. Replacement covers for the 4-tier and 5-tier greenhouses are available on Amazon. We’ve been able to get them for a reasonable price by waiting until they are on sale, which is usually outside of gardening season.

Unfortunately, the previous failures have not gone away. Year each year, the quality of the new covers seems to deteriorate. Not that we’re knocking it; it worked admirably for us for years. This will be the inspiration for our next DIY project, where we’ll implement the same ideas. In theory, this should prove to be a more long-term answer.