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Ultimate Guide to Greenhouse Growing in Winter

A greenhouse can protect hardy plants from frost damage while ensuring optimal growing conditions for crops, even in winter.

Growing crops in a greenhouse ensure warmer soil, steadier temperature, and moderate humidity. It promotes good crop harvest all year round. To grow the plant inside one, prepare a greenhouse using a heating system, thermal mass, and grow lights.

There are multiple walk-in greenhouses (DIY and commercial) available to yield optimal harvests of vegetables and herbs.

Thus, stick with the article till the end to learn how to make one so you can grow different crops during winter.

Can You Grow Plants in a Greenhouse During Winter?

A greenhouse is a microclimate system built using an enclosure with a transparent roof and wall to let sunlight in and maintain a warmer indoor climate.

It can give gardeners complete control over the environmental parameters that can be adjusted per plant needs.

Thus, growing plants, including crops, veggies, flowers, and herbs, is possible year-round in a greenhouse.

By upgrading the greenhouse using sun lamps, heating pads and humidifiers, you can create ideal growing conditions for plants during winter.

Besides, other pros of growing crops in a greenhouse involve.

  • Allows to headstart seeds of tender plants that require warmer months.
  • Protects tender crops from harsh sunlight throughout the summer months.
  • To grow exotic, heat-loving crops like okra, melons, and peppers.
  • Increase the use of sunlight throughout autumn to extend summer crops.
transparent greenhouse with multiple plants in a red pots during winter
A greenhouse enables gardeners to control the parameters suitable for ideal plant growth even when the outside environment is unfavorable.

While it is primarily true that a greenhouse is preferred for warmth-loving crops, the same can be used to grow cold-hardy crops for better yields!

Also, greenhouses are beneficial even when growing crops in summer to keep producing harvests.

Thus, you can aim to grow crops in the greenhouse during winter for optimal harvest.

What to Grow in the Greenhouse?

Plants requiring sun would benefit most from greenhouses as it enables them to make the most of the sunlight.

Alternatively, it can be used for particular winter plants that need a conducive growing environment.

Consider the following plants if you only start to use the greenhouse now.

PlantsTemperature Requirement

Dahlias, Begonia, Lilies
Alocasia, Monstera, Cucumber
Eggplant, Pepper, Pumpkin
Squash, Tomato, Bay
Curry plant, Oregano

60-75°F (15-23°C)

Half Hardy
Zinnia, Cobaea, Amaranthus,
Blue sage, Beets, Spring Carrots
Lettuce, Pea, Cauliflower
Parsley, Chives, and Thyme Lemon

50-55°F (10-12°C)

Hawthorn, Foxglove, Fennel
Lavender, Potato, Turnip
Radish, Brussels Sprouts and Daisy

45°F (7°C)

Besides, you can grow winter vegetables like Kale, Carrots and Turnips outdoors with minimal frost protection.

Required Tools to Grow Plants in Winter Greenhouses

Growing plants inside a greenhouse will be very similar to growing them outside. The difference is that the environment is under control.

But before getting your hands dirty, gather these tools necessary for a DIY greenhouse.

Gardening Potting Mix1. Choose moist peat free compost with a thin layer of vermiculite for seedling.
2. Use one part organic material (peat or coir) and inorganic material (perlite, vermiculite) with homemade compost or worm casting.
Plant CagesAttaching cages will help to stake tomato bushes when it begins sprawling.
Rake and TrowelTo mix in potting mix, aerate the compact soil, and fill the gaps without the soil.
LED Grow Light1. Install appropriate grow light wth UV to induce seed growth
2. provide optimal lighting when the sunlight is scarce.
Heating Unit1. Install a portable heating unit that can be controlled by a thermostat.
2. Measure the square footage of the greenhouse before deciding wattage and number of space heaters.
InsulationPolyethylene sheeting or aluminum foil insulation (1/4 thick) to insulate greenhouse wall during winter

How to Heat a Greenhouse in Winter For Free?

Winter greenhouse requires proper setup to grow plants like tomatoes that thrive in spring and summer.

It is especially true for Zone 3, which sees longer, colder months and snow, requiring a few extra measures to warm up the greenhouse.

Alternatively, the unheated greenhouse can not protect hardy plants from cold stress and sudden temperature drop.

Here are some DIY tips for heating your winter greenhouse!

1. Create a Thermal Mass

Creating a thermal mass or heat sink inside the greenhouse will prevent heat from escaping and help circulate the warmth.

Add a water barrel inside the greenhouse and place where it can get the most sunlight, usually the north wall.

2. Use a Heating System

Consider installing a heating system. An electric space heater, Klimaheat, or thermostatically controlled heater to achieve the required warm temperature.

Aim to achieve anywhere between 70-80°F (24-28°C) temperature to mimic the sunny days inside the greenhouse.

3. Insulate the wall

Insulating the walls would be helpful when you live in a region with long cold months or severe temperature drops.

Use horticultural bubble wrap to insulate the wall, or use horticultural fleece designed to protect the wall.

Alternatively, you can use transparent insulating materials to allow sunlight in.

4. Use Grow Lights

Using grow lights of the correct color helps with lighting up the space and raising the temperature.

The grow lights would be handy when growing seeds and young plants during fall or winter.

plants kept under the grow light
Aim to use full spectrum grow light that mimics natural sunlight.

Additionally, the led grow lights will provide UV light which helps produce flavonoids and terpenes, giving vibrant color and a rich smell.

5. Use Solar Water Heating

Install solar panels on the outside and run them underneath the compost pile.

The solar light irradiates the heat-collecting plate to generate hot water, which will heat the soil.

Tips to Care for Plants in a Winter Greenhouse

When growing the crops in the greenhouse during winter, avoid crowding plants, as it can reduce the yield per plant.

Aim for the following considerations to ensure optimal care in the winter greenhouse. 

  • Divide the greenhouse into zones and plant crops that can grow at close distances in one zone and others in another.
  • Use the space underneath benches for plants growing well on the ground. You can use small or large containers for the same.
  • Use HAF fans for better airflow and prevent the risk of diseases.
  • Also, avoid frequent watering as humidity remain constantly high.
  • Keep fertilizing the plants but in less quantity. 

Wrapping Up…

Depending on the availability of sun to heat the greenhouse, you can choose a deep winter greenhouse or a heated unit.

Also, you need to accept the varying growing requirements of plants in a greenhouse and outside.

All The Best!

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