How to Winterize a Greenhouse in 4 Steps: A Comprehensive Guide

We share some amazing tips and tricks on how to prepare your greenhouse for winter and give in-detail instructions
By
Nora Held
Nora Held
Research Writer
Apart from being our main writer, Nora also works for a number of gardening-related sites and magazines, sharing her experience as an owner of a small farm in North Carolina read more
reviewed
Reviewed By
Bruce Williams
Bruce Williams
Expert Consultant
Bruce owns a small farm and loves to grill since his early childhood. He’s a professional cook, but hiking and enjoying the great outdoors is his no less favorite part of read more
Last updated: August 17, 2023
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Winter is coming. Although there are no white walkers, your plants are in danger. Using a greenhouse can help increase plant yield in unfavorable weather conditions, but sometimes, it’s not enough. The usefulness of a greenhouse is that it traps heat from the sun in the daytime, allowing plants to stay warm on cold nights. But what happens when there’s no heat in the day?

This is why you need to winterize your greenhouse. Winterizing your greenhouse for winter season means you can guarantee that your plants will thrive despite the cold weather and pave the way for a lush garden next spring. In this article, you’ll find out how to winterize your greenhouse at the right time, and ultimately, achieve the perfect winter garden.

Why Is It Important to Winterize Your Greenhouse?

Plants are affected by cold in several ways depending on the site, soil, duration of cold and other factors. Cold freezes the plant cells, causing damage to nutrient and water pathways. This damage can lead to wilting and sometimes the death of your plants. Even hardy plants have a tough time in severe winter without protection, with flower buds dying off Trusted Source Landscape: Effects of Cold on Landscape Plants | Center for Agriculture, Food, and the Environment at UMass Amherst Some New England winters are characterized by relatively mild temperatures, or at least by a lack of extreme cold. It is also not uncommon, however, for temperatures to dip to near record-breaking levels. Following periods of extreme cold, many in the Green Industry ask about the impact such temperatures may have had on plant materials in the landscape. That kind of question ag.umass.edu . A good greenhouse for winter is therefore essential to preserve the growth and health of your plants.

Greenhouses are great for growing plants, not just in the winter months but also in the summer. They help trap heat from the sun to keep your plants healthy and warm. If you’re using a large greenhouse kit like the Ohuhu Green for Outdoors with Observation Windows or a walk-in, small greenhouse, like the Gosunny 4-Anchors Greenhouse, it is crucial to winterize your greenhouse to protect your plants in winter.

Your greenhouse’s proper annual winterization measures will entail sanitary measures, preventive measures, structural repair, and pest control procedures. This process helps to ensure the durability of your greenhouse in the winter months. It guarantees that the infrastructure will handle the dangers of winter with minimal wear and tear.

4 Steps to Prepare Your Greenhouse for Winter

With winter drawing near, now is the time to prepare your greenhouse for winter. Below are some essential steps to follow as you winterize your greenhouse:

#1. Clean Up Your Greenhouse

How to Winterize a Greenhouse in 4 Steps: A Comprehensive GuideCleaning up your greenhouse and planting equipment helps you arrange and organize your space to allow your greenhouse to operate at optimum efficiency. This process should be done in the fall to allow for adequate time for winterization. Proper and thorough cleaning also helps to reduce the risk of harmful pests. Some tips to consider when cleaning include the following:

  • Clear everything from the greenhouse. Disinfect and remove benches and empty your gardening pots.
  • Clean and disinfect all your greenhouse equipment with cleaning solutions.
  • Wash the surfaces of your greenhouse with a mild solution of detergent and a non-abrasive rag or sponge. Give the structure a good scrubbing, especially areas highly concentrated with moss, algae, or mold.
  • Air-dry the greenhouse by opening all doors and vents or using a fan.
  • Clean the glass and polycarbonate panels with cleaning solution in spray bottles.
  • Use biodegradable cleaning products to prevent harm Trusted Source Environmental impact of cleaning products - Wikipedia en.wikipedia.org to your vegetables and plants.

#2. Inspect After Cleaning

How to Winterize a Greenhouse in 4 Steps: A Comprehensive GuideCareful inspection of your greenhouse is essential for the smooth operation of your infrastructure. Any damage or weakness can cause significant problems for you and your plants. Gaps, cracks, and holes are a major source of heat loss, as they’ll allow warm air to leak outdoors. The holes can also let in the winter wind and moisture, causing damage indoors.

If your greenhouse is not secure enough, you’ll also have to deal with pests getting into the structure. Make sure that you examine your greenhouse thoroughly to ensure that you’re not missing out on any factors that can pose a threat to your plants.

Some points to take note of as you examine your greenhouse include:

  • Inspect and securely close all vents, windows, doors, and exhaust fans. Ensure the structures can shut securely.
  • Lubricate all moving parts of the greenhouse, including vents, door hinges, and handles. You can make use of grease or silicone-based products. Lubrication ensures smooth and reliable operation with plunging temperatures.
  • Fix ripped polycarbonate and broken glass.
  • Re-caulk and seal any gaps around the foundation of your greenhouse, however thin or small.
  • Check for loose truss and frame connectors and tighten the necessary bolts and connectors.
  • Ensure the frame and covering of your greenhouse is strong enough to withstand heavy snow and harsh winds. Reinforce the structure where necessary.
  • Test all systems, like irrigation and heating, and make necessary repairs.

#3. Adequate Ventilation is Essential

How to Winterize a Greenhouse in 4 Steps: A Comprehensive GuideAdequate ventilation and air circulation are necessary to create a healthier environment for your plants in the winter greenhouse. The air within the greenhouse can easily become too humid and harm your plants. As a result, proper spacing and arrangement, ventilation systems, and interior greenhouse circulating fans are necessary. They help to equalize temperature and circulate heat, prevent various pest problems, minimize mold and mildew and stimulate healthier plant growth.

#4. Heat and Insulate Your Greenhouse

How to Winterize a Greenhouse in 4 Steps: A Comprehensive GuideHeating and insulating your greenhouse are the two most important steps to prepare your greenhouse for winter. An integrated heating system is an absolute must when winterizing your greenhouse. It is necessary to inspect and service your heater before and during winter. Check and test the accuracy of thermostats and environmental controls to affirm that the heating system is functioning properly. The heating unit must pack enough power to supply the whole of your greenhouse. A good heater can quickly heat up large spaces, measure the indoor ambient temperature, and easily operate in your greenhouse. You can’t go wrong with the Plasma Greenhouse Heater. It checks all the boxes and is one of the best heaters out there. You can also have a backup electric heater and additional heating aids if the primary heater breaks down.

You’ll also need effective insulation strategies after you’ve installed a working heating system. Replace any worn cladding, and seal any cracks or gaps you find with heat-retaining silicone caulk or a simple duct tape. You can also tape translucent bubble wrap with greenhouse clips, staple guns, or duct tape to the walls, ceilings, and windows to provide adequate insulation.

Great insulation shields can even help reduce stress on your heating system, with one of the best quality products being Reflective White Foam Insulation Heat Shield. It has reflective aluminum polyester film on one side and a white vinyl cover on the other and provides lightweight but durable insulation. It can be cut easily and taped to windows and walls to insulate and protect your greenhouse from mold, mildew, and pests.

You will have to experiment a little, especially during your first winter, to discover what is best for your greenhouse in this season.

The process is time-consuming and requires some amount of effort, but winterizing your greenhouse is definitely worth the hassle. These steps are sure to reward you with healthy, thriving plants all winter long.

Tips and Tricks to Winterize Your Greenhouse

How to Winterize a Greenhouse in 4 Steps: A Comprehensive GuideIf you’ve followed all the above steps, good for you! You’re now on your way to having healthy plants throughout the winter season. Take note of these additional tips to help you ensure everything goes smoothly.

  • Protect your water lines from freezing by disconnecting and draining them. Hand water your vegetables, flowers, and other plants during winter.
  • Service your water systems by draining and cleaning the water tanks, filters and screens.
  • Get good plasma grow lights if you use a hydroponics system to increase your greenhouse harvest in winter.
  • Prepare the soil of the greenhouse by removing debris and dead or diseased plants.
  • Get plant covers to protect your plants against frost during cold weather.
  • Plan for the heat distribution in your greenhouse by determining the warmest and coldest areas.
  • Harvest your winter plants at the warmest time of the day.
  • Close all fans and vents that are not necessary for winter cooling.
  • Increase your heat output by cleaning out your radiators, ducts, pipes, and the entire heating system.
  • Protect against disease by removing fallen and frozen leaves and clearing out debris and dead material.
  • Ensure no plant is touching the polycarbonate walls to protect them from freezing.
  • Create an emergency checklist with the necessary supplies in the event of a freeze.

The quick video below goes once again through the process.

Final Thoughts

By following these tips to winterize your greenhouse, you can make it a safe haven for your plants throughout winter. Like we’ve mentioned throughout this article, timely maintenance and winterization of your greenhouse are essential to the survival of your garden plants in the frigid winter weather.

A winterized greenhouse allows you to grow a wider selection of vegetables, flowers, and shrubs. If you want to avoid starting over in the spring, a winterized greenhouse is your best bet. We’ve shown you how to winterize a greenhouse; all that remains is for you to make the most of the information we’ve provided. By following the tips and steps provided, you’re sure to have a flourishing and fruitful garden, even in the worst of winter.

References

1.
Landscape: Effects of Cold on Landscape Plants | Center for Agriculture, Food, and the Environment at UMass Amherst
Some New England winters are characterized by relatively mild temperatures, or at least by a lack of extreme cold. It is also not uncommon, however, for temperatures to dip to near record-breaking levels. Following periods of extreme cold, many in the Green Industry ask about the impact such temperatures may have had on plant materials in the landscape. That kind of question
2.
Environmental impact of cleaning products - Wikipedia

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