Winter Greenhouse

Tips To Build A Temporary Winter Greenhouse

Setting Up An Offseason Greenhouse

Setting up an off-season greenhouse can be a great way to extend your growing season, allowing you to cultivate plants year-round. This guide will walk you through the process of setting up your own off-season greenhouse and provide suggestions on what to grow.

Choosing a Greenhouse Construction Material

The first step in setting up an off-season greenhouse is selecting the right structure. Consider factors such as size, material, and design. A sturdy greenhouse that can withstand harsh weather conditions is essential. Glass and polycarbonate are common materials used for greenhouses due to their durability and light-transmitting properties.

Choosing the right material for a temporary greenhouse can vary depending on your specific needs, climate, and budget. However, here are a few key factors to consider:

The frame of your greenhouse should be sturdy enough to withstand wind and weather conditions. Aluminum and steel are common choices due to their durability, but PVC can also be a cost-effective alternative.  This also depends on how temporary this is going to be which will obviously affect the cost as well.  Make sure the greenhouse is exposed to the morning sun in the east or south for exposure and protection from the wind in extreme climates. If you are not getting enough light, artificial grow lights may be needed for additional light.

poly-built greenhouse

The covering or glazing material is what allows sunlight to enter the greenhouse. There are several options to consider, Polycarbonate is a type of plastic that is incredibly durable and offers high light transmission and is more insulating than glass and can be installed over a steel or wood frame and be taken down if installed properly, stored and re-used again the next winter.  If cost is the biggest factor, polyethylene film or “Vis queen” is very inexpensive and easy to replace, but if you live in a windy state as I do, it may not hold up well in the wind unless installed properly.  Glass of course is the ultimate way to go however it is expensive, hard to install and less insulating than polycarbonate.3 greenhouses

Consider the amount of space you have available and what you plan to grow. Adding a glass or polycarbonate enclosure to your covered patio or porch may be an option depending on your construction.  Some home owner associations have restrictions against altering the appearance so check with your HOA if one exists for your neighborhood.

Ensure the greenhouse has adequate ventilation to control temperature and humidity levels.  Also keep in mind a greenhouse often has high levels of humidity which is what helps those herbs, plants, and veggies grow, so plan for exhaust or windows that can be opened a bit to allow air transfer.  One time I had a glass greenhouse extension on the back porch of my home that was a glass and aluminum framed structure.  I also put a low grade heater in there to run during the coldest days and it was amazing how well the plants, flowers, and vegetables grew and produced during winter, but it was usually too humid to sit out there and relax…

You will want to choose plants that can thrive in colder temperatures for winter growing such as carrots, spinach, and kale.  Then in summer rotate to heat-tolerant plants like tomatoes, cucumbers, peppers, basil and the like.  It is so critical to have healthy soil whatever the greenhouse, make sure you use plenty of compost or an all natural soil amendment such as the Covington Rich & Gooey Sticky Soil Food.  Test your soil twice a year for PH and nutrient levels for best results. 

I thought I would include a little bonus on "what to plant" during those winter months, if curious read on! 

What to Grow in a Winter Greenhouse: A Comprehensive Guide

A winter greenhouse is a fantastic way to extend your growing season, allowing you to harvest fresh produce even in the cold months. While it might seem counterintuitive to grow plants in the winter, many varieties thrive in cooler temperatures and can be quite productive in a controlled environment like a greenhouse. Here's a guide on what to grow in a winter greenhouse.

  1. Leafy Greens

Leafy greens are some of the most reliable crops to grow in a winter greenhouse. They are cold-tolerant and quick-growing, making them ideal for winter harvesting. Some options include:

  • Lettuce: Lettuce is a cool-season crop that grows well in a greenhouse during winter. Varieties such as romaine, butterhead, and loose-leaf are great choices.
  • Spinach: Spinach is highly cold-tolerant and can thrive even in the coldest months when grown in a greenhouse.
  • Kale: Kale is another leafy green that can withstand frost. It becomes sweeter after a frost, making it a great winter crop.
  • Swiss Chard: This plant is resilient and can provide a continuous harvest throughout the winter.
  1. Herbs

Herbs are great to grow in a winter greenhouse because they're not only useful for cooking but also quite hardy.

  • Parsley: This biennial herb can easily survive the winter in a greenhouse.
  • Thyme: Thyme is a perennial herb that thrives in cooler temperatures.
  • Rosemary: This evergreen herb is perfect for a winter greenhouse as it prefers cooler, well-ventilated conditions.
  1. Root Vegetables

Root vegetables are great winter crops because they grow underground, where they're protected from the harsh weather.

  • Carrots: Carrots are surprisingly hardy and can be grown in a winter greenhouse for a late winter harvest.
  • Beets: Beets can tolerate frost and are a great choice for winter greenhouses.
  • Radishes: Radishes are quick-growing and can be harvested multiple times throughout the winter.
  1. Brassicas

Brassicas are a family of plants that include many cold-tolerant vegetables.

  • Broccoli: Broccoli is a cold-hardy vegetable that can produce well in a winter greenhouse.
  • Cabbage: Cabbage is another brassica that's incredibly hardy and perfect for winter growing.
  • Cauliflower: Cauliflower can be a bit tricky to grow, but with the controlled environment of a greenhouse, it can thrive in the winter months.
  1. Alliums

Alliums are a group of plants that include onions and garlic, which are excellent for winter growing.

  • Onions: Onions can be started in a greenhouse in late winter for an early spring harvest.
  • Garlic: Garlic is typically planted in the fall and harvested in the summer. A winter greenhouse can provide the perfect conditions for it to grow.

Tips for Growing in a Winter Greenhouse

  • Temperature Control: Ensure your greenhouse stays above freezing. You can use heaters, thermal masses, or insulation to maintain a consistent temperature.
  • Lighting: Winter days are short, so consider supplemental lighting to help your plants grow.
  • Ventilation: Good airflow is crucial to prevent disease and promote strong plant growth. Make sure your greenhouse has adequate ventilation.
  • Soil Preparation: Use compost and organic matter to prepare your soil. This will provide your plants with the nutrients they need to grow.

A winter greenhouse can be a productive space even during the coldest months. By selecting the right crops and providing proper care, you can enjoy fresh produce all year round.

Plan your planting and harvesting schedule carefully to make the most of your greenhouse space and have succession planting where you plant new crops as soon as you harvest the old ones in order to maximize space and yield.  And whatever you do, share the spoils with your neighbors to give back some of what Mother Nature has Blessed you with. 

Keep Growin’ Papa Zeep!

papa zeeps soil food with tomatoes