The arrival of winter is a momentous occasion that many greenhouse growers work all through the season to prepare for. After all, it’s the #1 reason why people grow with them in the first place – season extension, and to push yields as far into winter as possible

This is because greenhouses are first and foremost warming structures, absorbing and trapping heat to the benefit of any plants growing within them. Without them, you’re not able to optimize your seasons like many growers who use them are able to. This is because they create comfortable environments for plants, thus nurturing them far past their natural seasonal limits on their own.

Greenhouses extend your season, allowing you to grow more and for longer. You’ll then enjoy your hobby well into colder times, or boost productivity with your business by making more money with higher yields as an entrepreneur – if you so choose.Regardless of the benefits you seek, when winter comes around it’s crunch time for greenhouse growers!

FACING DOWN THE WINTER

If you have a setup for your growing structure (and particularly for the warming protection of your plants), it’s when temperatures get at their coldest that you’ll want to ensure that things are working adequately.

To be clear: when left to their own devices, greenhouses perform admirably and exceptionally! But for lovers of efficiency – and those who want to be wise in the face of winter – there’s a lot more you can do with your structure to fully “winterize” it, guaranteeing that you and your plants are in fact ready for the cold temperatures to come.

Let’s face it: accidents, damage, and wear can and do happen to greenhouses over time, and all these impact your plants’ environment. Don’t know how you can enhance your setup for winter? Whether you’re a beginner or an expert, the following tips will be a huge help to your greenhouse heading into winter. I’m sure you’ll be new to some of them as well!

1. KEEP DOORS CLOSED

This tip should be obvious, but always bears repeating: come winter, always make sure that the doors to your greenhouse remain closed as much as possible.Take better steps to remind yourself, your employees, or anyone else who shares or works in your structure about this important measure. An accidentally cracked door, even for a few hours, can mean life or death for some of your precious plants – especially during the coldest times of year.

Use this knowledge and apply it to any other possible openings in your building as well: vents, windows, or flues, especially if any of them ultimately allow for cold air or drafts into your structure. Seal up your grow space, and you ensure that you’ll be sitting pretty with bountiful harvests (and lively plants) come spring (or even earlier!).

2. REINFORCE YOUR DOORS

What could be better than making sure your doors are shut at all times? Well, there is one thing: making sure that your doors work well in the first place! Many DIY doors (and larger doorway “ends” to structures) on high tunnels and greenhouses, though well-constructed, are sometimes made with only one layer of plastic. Further, since they are the most used and handled parts of the structure overall, they’re also the more vulnerable to punctures, drafts, cracks, and even loosened plastic over time.

Consider adding another layer of plastic to one side of your door, if only one side of your constructed portal is covered in plastic. Many doors may only have plastic affixed to just one surface of the door itself, so doubling up can really make a difference.

Check your doors closely too: when they shut, do they close flush with the wood of the doorway frame? This applies to doors you make yourself, as well as prefabricated doors you have installed into your structure. If you do see sizeable cracks, these will give way to cold drafts and will most certainly affect the efficiency of your greenhouse as well.

Installing shims in your door frame to even things up – or even adding seals to the door edges and bottoms, much like with a freezer – further ensures that your grow buildings are pulling their weight.

3. DO MAINTENANCE: CHECK FOR HOLES, PUNCTURES, DRAFTS

As stated in the previous tip, checking for punctures, drafts, cracks, and even loosened plastic is important to prevent drafts. These in turn lower the temperature and function of your greenhouse.

Make sure to check for this on the plastic on your doors where your structure is the most handled and used. But this also applies to the plastic all over! Winds, tools, equipment, tree branches, animals, and more can all punch holes in your structure on accident. If holes and tears are small enough, sometimes a little bit of industrial tape over the hole may do the trick of keeping things together and preventing drafts.

However, if tears and rips are sizeable, it might be time for greater measures. Larger punctures are very difficult to repair. Plus, a strong windstorm can turn a small tear in a greenhouse into a shredded, flapping mess overnight. If you see such tears or numerous punctures, it would be smarter to invest in a new plastic covering outright, and re-cover your frame long before winter’s winds come around.


4. CHECK AND REPAIR BASEBOARDS

In lieu of checking your doorways and plastic, make sure to give your baseboards a good look-over! Tears and cracks can happen in the plastic around these spots, too, so reattach or reinforce them if you can. If the damp and elements have done a number on wooden baseboards, repair and replace them completely before cold weather, especially if rot is starting to work them apart.

Don’t have time or money to invest in such repairs right away? No problem! Many clever greenhouse growers add thick layers of insulation around their baseboards in a pinch, such as haybales, blankets, or earth – while some even regularly sweep snow around their structure’s bases when there’s plenty of it to be found.

5. GOT ELECTRICITY (OR NOT)? RUN A HEATER

If you have the luxury of an electric hookup inside or near your high tunnel or greenhouse, then by all means, consider running a heater in your sheltered grow space! For a small- to medium-sized high tunnel or greenhouse, this can work wonders, though it may add a bit to your heating bill for the season.

Even the average room heater can make an impact if you plug it in, though be careful: only run it on a timer, set a shut-off time for it, and make sure to keep it away from anything flammable in your greenhouse.

If you have a very large high tunnel or greenhouse, investing in actual built-in heating systems can be a huge plus. A room or space heater won’t be as efficient, either functionally or money-wise. Larger options are available, which include gas-powered heaters or even large wood stoves if you have the time or money to invest in them.

6. USE ROW COVERS, COLD FRAMES, OR LOW TUNNELS INSIDE

There’s many ways to check on and seal up the actual structure of your greenhouse for protection against cold. If you’ve done all you can to reinforce your larger structure – but still feel concerned about keeping your plants warm – consider the use of smaller coverings within.

If your greenhouse is not crowded with tables or benches, and you’ve got plants growing straightaway in the soil within, setting up a cold frame, low tunnel, reemay, or fabric row cover is really no different than the process of setting one up outside. The only difference: your plants will be double-protected against any cold or drafts that could possibly sneak inside your greenhouse.

7. TURN BENCHES AND TABLES INTO COVERINGS

If you have a greenhouse filled with growing tables and benches rather than actual soil beds, working with cold frames or low tunnels may not be the best option. But that doesn’t mean you can’t invest in smaller covers under your larger cover. It can be an even simpler process to turn your benches or tables into actual covers themselves!

Simply gather all your plants and flats under your grow tables and benches, and drape your plastic, reemay, even blankets or other covers over them to create mini-covers. This way your plants can also experience that double-protection and boost of extra warmth. Just make sure that you open up your covers and give them a little sun every morning!

8. EXTRA PLASTIC? DOUBLE-WRAP YOUR GREENHOUSE!

It’s such a simple and genius idea – and yet, not many people think of it. If you really want the optimal warmth and efficiency out of your greenhouse – and you just so happen to have extra plastic, or extra money to invest in more – putting a whole other cover over your greenhouse, only temporarily for the winter, can keep things nice and snug.

You may need a helping hand to get your plastic up and over your structure. But once it’s up, worries about cracks, drafts, and tears are not nearly as bad. Once weather warms back up again, simply pull the extra plastic cover off, fold it up, and your greenhouse is good to go!

NOW THAT EVERYTHING’S COVERED…

Winter is the most daunting time of year for greenhouse growers, and a pivotal time to make sure your structure is doing what it was meant to do. Equip yourself with these tips, however, and you’ll be set to both troubleshoot AND tighten up your greenhouse to continue growing amazing plants – even through winter!

Contributer: Adrian White

Adrian White is an organic farmer and gardener of 8 years, and a food, health, and agricultural writer of over 5 years. Now living in Iowa, she has administrated CSA’s as well as farm packing operations, fueled by a passion for being a young organic farming presence in an ag state that sorely needs a new generation of farmers.