How to Prepare Your Greenhouse For The Fall

Autumn is finally here, and the time has come to begin prepping your DIY backyard greenhouse for the cooler months ahead. Regardless of which planting zone you live in, this comprehensive guide outlines all of the key steps you should take to get your greenhouse in tip-top shape so your garden can thrive this season. 

In this article, we will discuss:


Tidy Up Your Garden Beds

Out with the old and in with the new. It’s essential to remove any seasonal plants that are unlikely to survive during the fall and winter months. In addition, this is the time to uproot and discard any diseased plants and focus on picking all of those pesky weeds. This means that when you’re ready to begin planting your next crops, you’ll have a beautiful blank canvas to work with. 


Customer images of clean garden beds

Disinfect Your Greenhouse

  • Sweep your floor and clear out all the excess dirt – this will help remove any unwanted insects or pests that could be troublesome in the cooler months. 
  • Sanitize your floor and equipment – this is a great way to prevent any bacteria or diseases from previous crops from crossing over onto your autumn and winter harvests.
  • Disinfect your benches and tables, and wipe down your polycarbonate panels with water and mild liquid soap. This will ensure that everything is squeaky clean and ready for the next season.


Conduct a Soil Test

Soil tests are a great way to ensure your plants have what they need for healthy growth. For gardeners hoping to continue growing into the cooler months, this test will tell you about your soil’s pH balance and nutrient levels.  

If you’re having any issues with your soil composition, you can try the following home remedies to get things back to the correct levels:

  • Low pH: Try adding Lime (ground limestone rock) to reduce acidity.
  • High pH: Add Elemental Sulfur or Peat Moss to reduce alkaline.
  • Low Nutrients: Experiment with natural fertilizers to increase nutrients.

Loosen the Soil

Be sure to give your plants the best care possible by making sure they have loose, aerated soil. Over the summer, the earth can become compacted, which can cause problems for root vegetables and prevent proper water drainage. Just run a garden fork through your soil to fluff it up and ensure there’s plenty of room for your subsequent crops to grow.


Customer images of aerated soil

Check Your Lighting

If you’re hoping to grow sun-loving plants throughout the autumn and winter, this may be difficult depending on where you live. LED grow lights are a fantastic solution for those expecting much darker months. However, different types and colours of lights can elicit different kinds of responses from your plants – so it’s best to make a plan and know what you’ll be growing throughout the autumn and winter before making this purchase. If you already have grow lights, now is the time to dust them off and plug them in to make sure they still work before winter rolls in. 

Customer image of their Sigma greenhouse with LED lighting

Winterize Your Greenhouse

There are a variety of measures you can take to ensure that your garden will continue to flourish well into the dark winter months. Autumn is the ideal time to start preparing your DIY greenhouse kit with insulation, heating, and ventilation, depending on what plants you’re hoping to grow throughout the cold season.


Decide What You Want to Plant

One of the first things you should do when preparing your greenhouse for autumn is to decide whether to grow warm-season or cool-season plants. This will help you determine your heating and lighting systems and any extra measures to take to keep your plants healthy and happy. 

  • Warm Greenhouse: If you want to test the limits of your greenhouse and opt for delicate warm-season plants, you should begin to explore consistent heating options and quality growing lights.

  • Cool Greenhouse: If you’re hoping to extend your growing season with cold-hardy vegetables, then simply insulating your greenhouse should be more than sufficient. 


Customer image of a heater in their Sungrow greenhouse

Start Your Seedlings

Try to start your seedlings with plenty of time before the first frost. In saying that, your greenhouse will buy you additional time provided it’s properly insulated. If you plan to opt for unpowered heating methods within your greenhouse, then it’s best to monitor the temperature inside daily to ensure your plants are getting the level of warmth they need to survive through the winter. While those with an electrically heated greenhouse have endless options for what vegetables to plant, the following is a list of crops known to thrive in colder temperatures.

Hardy Crops
These vegetables can withstand air temperatures below 28° F (-2° C).

  • Spinach
  • Sweet onion
  • Garlic
  • Leeks
  • Rhubarb
  • Rutabaga
  • Broccoli
  • Kohlrabi
  • Kale
  • Cabbage
  • Chicory
  • Brussels sprouts
  • Arugula
  • Fava beans
  • Radishes
  • Mustard
  • Turnips

Semi-Hardy Crops
These vegetables can withstand air temperatures at the lowest between 28° F to 32° F (-2° C to 0° C).

  • Beets
  • Carrots
  • Parsnip
  • Lettuce
  • Chard
  • Peas
  • Chinese cabbage
  • Endive
  • Radicchio
  • Cauliflower
  • Parsley
  • Celery
Customer image of their seedlings trays

Crop Rotation

A new season is a perfect time to rotate your crops. Planting a diverse assortment of vegetables can help you avoid having pests and diseases building up in the soil. In addition, a good system can help you replenish nutrients that have been depleted from previous plants. For example, if you’ve recently grown tomatoes or corn in a particular area, you can replace that crop with peas or broad beans to increase nitrogen levels again.

Note: It can be easy to forget what stage you are at in your crop rotations. We recommend keeping track of your garden beds in a notebook so you can always be prepared to swap in your next plants. 

Save Your Seeds

As you harvest the last of your summer crops, this is a great time to see what you enjoyed growing the most and would like to plant again. So, take the time to save the seeds from your favourite plants, dry them out, and store them until you’re ready to start focusing on those warm-season veggies again. You can save the seeds in paper envelopes, bags, or mason jars in a cool, dry place to prevent a build-up of mould or pests snatching them away.

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