Growers invest in greenhouses for many reasons. If you ask the average greenhouse grower they’ll most likely say they use greenhouses to extend their seasons in cold regions.
In simpler words, greenhouses help growers who want to keep producing well into the winter, a concept called “season extension.” Obviously, there are far more uses for greenhouses than this. This includes nursery plantings, simulating extremely controlled and ideal growing environments, light deprivation, and more— and not all greenhouses are designed to run in areas with harsh winters.
Even since ancient times, the main purpose of the original greenhouse was to protect and warm from the cold. Whether you run a glass, plastic, or other type of greenhouse structure, you’re more than adequately prepared for growing through the winter— with a few minor exceptions.
How are you sure that your greenhouse is ready for cold winter growing? Here are a few pointers on how to prepare your greenhouse for winter.
Do maintenance on doors and ventilation
Maybe you’ve never run your greenhouse through a cold winter before, and you’re wondering how to get it “winterized.” A good first step is to check doors, windows, ventilation, or anything else that needs good sealing in order for a well-run, functioning greenhouse to keep plants alive, thriving, and productive.
If there’s any fitting, vent, or other opening that could use extra checking (or even an update or replacement of gaskets, seals, etc.), do this well ahead of the colder months. If this is the first time you’ve ever thought about running your greenhouse through winter, be sure these seals and gaskets are nice and tight.
Check for holes, punctures, and drafts
In the same vein, you’ll want to give your greenhouse’s coverings or panels similar treatment, whether they’re glass, plastic, poly, or other material. Are they attached tightly to the frame? Are there cracks, tears, or punctures? If so, repairing (or fully replacing) these long before winter comes is essential for plants come the winter.
Along with maintaining seals and cracks in doors or vents, you’ll want to make sure there isn’t a single cold draft entering your structure by any means— torn seams or cracks in your greenhouse shell obviously lead to drafts, too. Regardless of where the draft originates, give your greenhouse a good walk and check for air currents, perhaps on a cool night before the end of the warm season.
Drafts don’t just threaten the health and yields of your crops. They can also be expensive: a “heat leaky” greenhouse is practically throwing your money out into the cold! On the other hand, an airtight and efficient greenhouse will keep your energy and heating costs much lower and save you money.
Replace or upgrade plastic coverings
Growers who use poly greenhouses (such as hoop houses and high tunnels) face some more unique challenges as winter approaches. Though these can also apply to glass greenhouses (and plastic panel greenhouses too), this section comes top recommended more so to the poly greenhouse grower.
In essence: repairing and patching up poly every year before winter can only go so far. Depending on its quality, poly will need to be fully replaced with a new covering every few years. Make sure to keep track of and acquaint yourself with the recommended lifespan of your specific brand or make of poly.
Why is this important before winter? Because cold temperatures are the ultimate breaking point for aged, degraded, and weak poly! It’s not uncommon for old poly to completely shatter in response to subzero or below freezing cold. For this reason, be sure to replace old poly far in advance of the cold season.
Install, check, and maintain heating elements
Obviously, if you’re taking the leap from a basic structure to a full-on winter ready greenhouse, you’ll absolutely need some sort of heating element! And you have so many options here: electrical heaters, gas hookups, radial heating, wood stoves, solar, and more.
For greenhouse growers who already have heating elements to keep plants thriving all winter long, it helps to do a bit of maintenance check to make sure these are in working order. If you plan on continuing a plant’s life cycle well past its frost kill parameters in a greenhouse, any hiccup in heating ability could mean damage, lower productivity, lower crop quality, or even crop loss within your greenhouse. And you certainly don’t want that!
Consider lighting setups
Keep in mind that season extension isn’t just about creating a warmer, more protected environment for your plants. It also means they need to get adequate light, too.
Come winter, most plants will stop growing once daylength drops below 10 hours. The exact time this happens depends on the latitude of where you live. If you want to keep huge, healthy plants and ramped up production all winter long, then you’ll need extra lighting inside your greenhouse structure to extend your season in terms of light, not just temperature.
Already have a lighting setup? Make sure it’s working well before the days start to get shorter, so your plants don’t skip a step in their growth and progress. Again, doing maintenance, testing, or replacement of old light systems is recommended.
Growers all over the country enjoy amazing success with greenhouses through the winter. Producing high quality crops despite the cold is an amazing way to boost profits— just make sure you’re prepared!