Gardening

Growing in the Greenhouse Year Round

greenhouse growing

Looking for tips for year-round greenhouse growing? You’ve come to the right place.

Greenhouses are designed to create the ideal climate and temperature for your garden plants, but in regions where hot summers and cold winters come around every year, keeping these ideal conditions consistent can be a challenge. 

Your greenhouse may require some alterations as the seasons change to help adapt the internal climate and keep it as consistent as possible—if consistency is your goal, that is. 

You may also plan to section out a part of the year to grow cold-weather crops or even tropical plants, meaning more changes and adaptation may need to be made as the seasons change. 

Thankfully, there are some tips and tricks available to utilize your greenhouse for nearly any desired temperature in any season. 

year round greenhouse growing

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Tips for Greenhouse Growing in the Spring and Fall

year round greenhouse growing
Photo: Unsplash

In most regions, spring and fall will be very similar in terms of greenhouse growing. 

In these times of the year, the daytime temperatures are generally at a point where neither a heater is required for heating nor additional fans for cooling purposes.  

Extra insulation is also not usually needed in these seasons, and the glass or plastic material is the perfect barrier to the outside world. 

While these seasons are generally the easiest times to control a greenhouse climate, there are still some additional changes that may need to be made to keep your plants happy. 

1. Ventilation

Regardless of the season or temperature, ventilation is of crucial importance to any greenhouse, and for a few different reasons.

Temperature Regulation

Even when outside temperatures are cooler, if the sun is strong enough, the temperature in your greenhouse may rise quickly, potentially overheating and killing or damaging your plants. 

Adding proper ventilation will allow hot air to escape and cooler air to flow through your greenhouse.  While you won’t necessarily want an open door or window in the spring and fall months, roof vents or cracked windows may be necessary. 

Humidity Regulation

Ventilation is also important in the spring and fall months for regulating humidity levels.  Most garden plants won’t do well in climates with high humidity—unless you are growing tropical plants exclusively. 

When you water your plants in a greenhouse, you are adding water to an otherwise closed environment, trapping all evaporated water within the space.  However, when proper ventilation is available, an appropriate amount of this water can escape, keeping humidity levels at a reasonable level. 

Carbon Dioxide

Another primary function of ventilation in your greenhouse is to allow carbon dioxide to naturally enter your greenhouse.  Plants require carbon dioxide to do photosynthesis, the process of converting carbon dioxide, sunlight, and water to glucose which is required for a plant’s survival.  If a greenhouse is completely closed off from the outside world, your plants will not be able to obtain the carbon dioxide they need to live and produce. 

2. Heating at Night

In many regions, nights can still get at or close to freezing temperatures during the spring and fall, especially the more north you are on the map.  Therefore, it is important to monitor temperatures with the use of a thermometer in your greenhouse—preferably a digital one that you can read from your home. 

When the temperature starts to drop too low at night, there are a few option to help keep your greenhouse warm.

Heater

One of the most straightforward answers to warming your greenhouse at night is to add a heater that you run overnight.  Many greenhouse gardeners utilize gas heaters that are rated for indoor use.  These heaters are effective and relatively cost effective to use. 

Electric heaters are also an option and are best used with a temperature monitoring shut-off device to ensure they don’t run too long or hot.

Water Bins

Another option for retaining heat in your greenhouse at night is to create a passive solar heat source by filling containers with water. 

These containers can be almost any size and generally range anywhere from milk jugs to 55-gallon rain barrels.  The water-holding containers should always be black to help absorb the most solar heat as possible.  If your desired container is not black, you can simply use spray paint to make it black.  During the day when the sun is strongest, the water in these containers will heat up. 

Once the sun goes down and temperatures begin to cool, the stored heat energy in the water will be released into the air. 

Compost

Another option for heating your greenhouse at night in the spring and fall seasons is to create a compost bin within your greenhouse. 

The composting process creates temperatures between 120 and 170 degrees Fahrenheit when done properly.  These temperatures will release into your greenhouse, effectively keeping it warm through cooler nights.   

Tips for Growing in the Greenhouse in the Winter

year round greenhouse growing
Photo: Unsplash

Winter poses a challenges for almost any region, as temperatures are generally lowest at this point in the year.  In regions where hard frosts occur and temperatures stay consistently low, these challenges become even more prominent. 

1. Heating

Heating your greenhouse in the winter is one of the most obvious challenges that comes with a winter greenhouse. 

As the temperature drops outside, it becomes more difficult to keep the inside climate at a consistently warm temperature, even when the sun is strong. 

However, there are a few options when it comes to warming your greenhouse in the winter.  Something to note—many complex or commercial-grade greenhouses (like Deep Winter Greenhouses) may not require any alterations to be winter-ready for certain crops and climates.  Most basic home-use greenhouses may require these alterations, however. 

Gas Heater

Gas heaters (propane, kerosene, natural gas, etc.) are a common choice among greenhouses that require heavy heating support during the cold winter months. 

Most gas heaters today are safe for indoor use and have low oxygen sensors to ensure a safe environment is kept.  Adding a heater with a thermostat and auto shut-off feature can help save you money by shutting down once a desired temperature is met.  However, keeping a gas heater full can be both time and financially consuming if you use it consistently.

Electric Heater

Electric heaters are another option for keeping your greenhouse warm during winter months.  These can be a convenient option if you have electricity available on site, or if you can easily run an extension cord out to your greenhouse.  However, depending on how often you need to run your heater, you may notice a significant increase in your electric bill. 

As with gas heaters as well, an auto shut-off feature is a good way to ensure your heater isn’t running unnecessarily once your greenhouse has reached the temperature you set.   

Insulation

Adding extra insulation to your greenhouse is another good way to keep it warm in the winter months.  Adding insulation can be used in addition to a heater to relieve some of the heating strain. 

To insulate the top half of your greenhouse, you will want an insulation that the sun is able to easily penetrate to ensure you are still getting solar heat and essential light within your greenhouse. 

Products such as bubble wrap allow a decent layer of insulation and sun exposure.  

To insulate the lower walls of your greenhouse, there are plenty of available options as sunlight is generally not as much of a concern. 

There are professional insulation products available as well as Styrofoam products and even leaves. 

Some gardeners prefer to add leaves each year because in addition to providing insulation, they release heat as they break down. 

Water Bins/ Compost

The use of water bins and compost, both discussed earlier, are also potential options for heating in the winter; however, these will likely not provide enough heat for those who live in colder climates. 

These warming methods may be used in addition to any of the previously mentioned heating methods as well as a supplemental heat source. 

2. Daylight

Daylight can be another concern throughout the winter months as the days get shorter, meaning less available sunshine each day. 

A majority of greenhouse-grown plants require a full-sun location, which is generally not a problem in the summer, fall, or spring as long as your greenhouse is positioned correctly. 

However, sunlight must usually be compensated for during winter with artificial lighting. 

Grow Lights

If your plants aren’t getting enough sunlight in the winter to grow, stay healthy, or produce crops, you may want to consider installing grow lights as supplemental light. 

There are several different types of grow lights including fluorescent, high-intensity discharge, and light-emitting diode lights. 

If you are growing plants that do not produce crops, a grow light that emits primarily blue light should be sufficient. 

Here you can find more information on which grow lights may be best for your greenhouse.

If you are growing vegetable or fruit plants and want to encourage the growth of produce, make sure the bulbs also have red light in addition to blue.  These bulbs are commonly referred to as full-spectrum. 

3. Watering

Another concern that some gardeners may have with greenhouse growing in the winter is having a reliable water source. 

If you generally water your greenhouse with a hose from your house, you may be out of luck in the winter if temperatures stay below freezing, as you will most likely not be able to use this hose. 

Fortunately, there are other watering options that will help ensure your plants still get the water they need without the need to haul water by hand each time. 

Add a Hydrant

Perhaps one of the most convenient solutions to getting water to your greenhouse is to install a hydrant in or near your greenhouse.  This process is essentially creating a small well from which you can pump water from the ground.  If you have the ability to add a hydrant within your greenhouse, a basic one may be just fine.  If you want to install one outside your greenhouse, it may be best to invest in a frost-free water hydrant. 

Use Your Water Bins

If you are using water bins to help create heat for your greenhouse, you can give these bins a second purpose by using them to water your plants as well. 

If you are using a barrel or bin that is off the ground, you may be able to use gravity to get water to your plants.  Otherwise, there is the option of adding a small electric submersible pump to your water source that will work water up through a hose.  Some of these pumps can be set on timers and attached to a soaker hose for hands-free watering. 

Store Your Hose

Finally, if you want to continue using your traditional water hose—if that’s how you were watering in the previous months—there is the option to remove it from your water spigot between each use.  If your hose is left outside in the winter, any water within it may freeze and become unusable. 

However, if you only use your hose when watering and then completely drain it and store it somewhere warm, it should be ready to bring out and use again the next time you need to water. 

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Can You Grow in the Greenhouse in the Summer?

year round greenhouse growing
Photo: Unsplash

While summer may seem like the ideal time for planting and growing, a greenhouse will pose its own set of problems during this time. 

Greenhouses are created primarily to keep the environment warm for plants to grow, but in the summer they can get too warm, potentially causing harm to any plants inside. 

1. Keeping it Cool

Making sure that your greenhouse does not overheat is one of the most challenging aspects of greenhouse gardening in the summer, but there are some ways to help keep it cool. 

Fans and Ventilation

One of the easiest ways to keep your greenhouse cool on those warm summer days is to open up any doors or windows during the day to create air flow which will help keep the area cool.  If you are not getting enough air flow by simply opening doors and windows, adding fans either as built-in systems, in louvers, or in open windows will also help. 

Shade Cloth

The primary reason why greenhouses get so warm in the summer is because the strong sunlight pours in all day, creating additional heat. 

One way to help cool your greenhouse when the sun is strong is to install shade cloth on areas where sunlight enters the greenhouse directly. 

While you may not want to create a full-shade environment for plants that require full or partial sun, a temporary shade cloth can alleviate brutally hot greenhouse climates.   

Evaporative Cooling

Evaporative cooling is the process of using the available heat to evaporate water which helps to cool your greenhouse.  This process can lower greenhouse temperature as much as 10 to 20 degrees below the outside air temperature. 

Most evaporative cooling systems consist of a fan and a pad, the pad is generally made from a cellulose material to which water is added. 

The fans blow through these water-filled pads and create a cooling system.  There are also simpler systems that consist of a water spray and fan setup. 

There you have it! Everything you need to know about growing in the greenhouse year-round. Get started today!

What tips do you have for growing in a greenhouse? Let us know in the comments!

Want to learn more about farming? Be sure to take a look at these other articles.

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Author: Samantha RainwaterSamantha Rainwater is a freelance writer, full-time business owner, and recent mom who spends her free time writing. Her degree in Biology gives her a background in science, which she likes to apply on her small hobby farm. Writing about her experiences is one of her passions, and she finds joy in sharing these experiences with others.

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