How to Prepare Your Greenhouse for Winter

Emma Loker Headshot - DIY Garden
Written by: - Gardening Expert
how to prepare your greenhouse for winter

Don’t assume your greenhouse is useless in winter. There are loads of things you can do with it. Spending time in your greenhouse in the winter, you get the added bonus of not getting wet! When it comes to using your greenhouse in the wintry months, preparation is vital.

Learn here how to get your greenhouse good and prepped for the cold season. 

Autumn Greenhouse Preparation

Autumn preparation is essential if you’re looking to use your greenhouse in winter. It takes a little bit of work, but it’s well worth it. You’ll come out the other side of winter with a greenhouse bursting with goodies!

Before the preparation begins, however, think about what plants you want to grow in your greenhouse during winter. If you want summer plants, you’ll need a heating system (we’ll go into this in more detail later on). If you want some cold-hardy veggies, you can skip the heat.


To get your greenhouse ready, you’ll need to:

  • Have a clear-out
  • Clean it
  • Get your soil ready for plants
  • Insulate it
  • Ventilate it
  • Repair any damage
  • Add some light
  • Sort out a heating system (if necessary)

Of course, you can opt-out of some of these. But to ensure your greenhouse plants are happy and healthy during winter, give them a try! 

Let’s go through each of these. That way, you’ll know exactly how you can get your greenhouse sorted.

Have a Clear Out

Remove your old, harvested plants to make way for the new ones. Getting rid of any diseased plants as quickly as possible can prevent the diseases from spreading to your new winter plants. 

Then, take everything out. Leave no stone unturned. Remove your pots, supports, trays, and shelves. If you’ve got ground-level compost in your greenhouse, this needs to be replaced every couple of years to ensure your plants get the nutrients they need.

Clean Your Greenhouse 

Now your greenhouse is entirely empty, give it a once over with a broom. Get rid of all that soil and dust hanging around.


Greenhouse Glass

When the glass is green, you know it needs to be cleaned. Even when it’s not caked in dirt, mould or algae, take some care to clean your greenhouse glass. Sparkly windows guarantee a plentiful supply of light and heat for your treasured plants! 

If you want something quick and easy, use a shop-bought glass cleaner. But if you’re attempting to avoid chemicals, try a vinegar and baking powder solution or just good old soapy water. 

Greenhouse Structure 

Take care to clean your greenhouse inside and out. Clean benches and structural elements with disinfectant to ensure no nasty diseases are left behind. Disinfectant also prevents pests from re-entering and hanging about! 

Dish soap and water is a homemade alternative that works just fine on metal frames. If your greenhouse has a wooden frame, try applying wood oil soap diluted with water using a sponge. 

When cleaning the structural elements, use a soft cloth or sponge, as a scraper or wire brush may cause long-lasting damage and weaken the frame. 

You’re forgetting something – the floor! The greenhouse floor is often overlooked, but it’s important to clean because it can still harbour pests.

Get Your Soil Plant-Ready

Now your greenhouse is gleaming, it’s time to get your soil ready. If you don’t have greenhouse beds, you can skip this step. 

If you’ve got greenhouse beds, however, get rid of all the old plants and detritus. Again, this is to make sure no pests or diseases are passed on to your winter plants.

Go on the hunt for some worms to add to your greenhouse beds. Worms churn up the soil, which circulates the air within it. They’ll get your beds ready for you!


Patch Up Any Damage

The last thing you want is to insulate and heat your greenhouse, only for the heat keeping your plants toasty to escape through holes and gaps. Give your greenhouse a once over, checking whether there are any areas of damage. You can do this while you’re clearing out and cleaning!

Here’s a list of what to look out for:

  • Damage to the structure, including cracks, gaps, and holes 
  • Cracks or holes in the glass itself
  • Broken or defective hinges 
  • Check that the door doesn’t get stuck, and check for gaps around the door frame when it’s closed 

Repair any damages. Use silicone caulk to repair small holes and gaps or duct tape if you’re desperate. And while you’re at it, oil your hinges! You don’t want to be locked outside your greenhouse because of a jammed door. And you definitely don’t want to be trapped inside it! WD-40 will do the trick.

Autumn brings with it some beautiful, dry days, making it the perfect time to complete these little tasks. 

Insulate, Insulate, Insulate!

Just like fixing holes and other damage, insulating your greenhouse stops all that essential heat from escaping. Insulation will keep your plants warm and prevent exposure to the outside elements. 

If you insulate well enough, in fact, you don’t need to add an artificial heat source! If it keeps all the heat from the sun locked inside, that’s your heater right there. 

While you’re searching for a silicone caulk to close up those annoying gaps and cracks, check its heat retentive. Heat-retentive silicone caulk does two jobs at once: it repairs and insulates!

Bubble wrap is an excellent insulator. It’s cheap and protects plants from UV ray damage, too! Insulate inside and out, creating a bubble wrap curtain just inside the door to prevent heat from escaping when you open it.  

You can also insulate your pots individually. Swaddling them is sure to keep them nice and warm!

Although bubble wrap is the best budget insulator, it doesn’t do well against the elements. An alternative is straw bales – perfect for outside your greenhouse, but they quickly clutter up the inside. 

Energy curtains are another helpful alternative. They separate the inside of your greenhouse from the troublesome cold outside, protecting your plants from getting a chill. Just don’t forget to open them back up when it gets light!


Ventilate Your Greenhouse

Plants need oxygen and carbon dioxide to thrive. Airflow is also essential because, without it, damp creeps in. And this accelerates the spread of diseases! 

Your plants will suffer without good enough airflow. But how do you do that without compromising heat? 

Installing a ventilation system like a fan is a sure-fire way to circulate the air while keeping the warm heat inside. But if you can’t afford a swanky system, try opening your greenhouse door on a bright, sunny day when the temperature isn’t too chilly. This should do the trick!

Add Light 

Those dark winter days don’t just affect our mood. They affect our plants, too! Plants need light – if they’re not getting enough, it won’t be good news, I’m afraid. 

If you know your plants need a good amount of light, consider implementing a lighting system. First, think about temperature and crop type. You can get heated artificial lighting, which some plants will love but others won’t! 

Your artificial light needs to match up with your greenhouse’s temperature and CO2 enrichment, so choose wisely.


Ready the Heat – If Necessary!

Is your greenhouse still not retaining warmth? Apply the heat! 

Artificial heat won’t always be necessary. If you’re growing winter-hardy crops, artificial heat is money wasted. But if you know your plants prefer warmth, think about introducing a heating system. Heaters are great for giving out intense bursts of heat. Choose between electric, gas, or battery-run heaters. 

If you’re worried about cost, try heat-absorbing black barrels, heat-retaining rocks or lava rocks. These are cost-effective alternatives, but they don’t work as well, unfortunately.

Prepped and Ready

Your greenhouse is prepped and ready for the cold winter months. It’s cleared of old plants and sparkling clean, your soil is prepared, and you’re keeping the heat in whilst maintaining all-important airflow.

All you have to worry about now is what delicious dishes you’re going to conjure up with your scrummy winter veg!

How useful was this post?

Click on a star to rate it!

As you found this post useful...

Follow us on social media!


Before you go, save up to 50% with these incredible gardening deals…

See Today's Best Garden Deals on Amazon No Thanks
Scroll to Top