Growing in a Winter Greenhouse
As the weather turns cool, the greenhouse comes into its own, allowing you to safely grow plants that would otherwise die as the winter advances. To maximize your winter greenhouse gardening success, you’ll need to ascertain the temperature, humidity, light conditions, and available space for your winter garden.
Read on to find out which plants will do best in your winter greenhouse, and how to help them thrive.
Plan Your Space & Make a List
Be sure you know exactly how much room you have to work with before you start buying plants, and determine the physical characteristics of your space. Is your greenhouse warm enough for everything you want to grow, or will you need supplemental heating?
Once you have this information, start a plant list. Following are some plants that enjoy cool evenings, and those that want to be bathed in warmth. For other ideas on plant choices, visit your local nursery, or contact an agricultural extension agent. You can even check seed packets for growing specifications.
Some Like It Cool
Here’s a quick sampling of popular plants that are comfortable with 40-50° nights, which may require minimal heating or no heating at all, depending on your local climate.
- Brussels sprouts
- Fava beans
- Swiss chard
- Easter lily
- Sweet olive
Some Like It Warm
Most plants prefer minimum temperatures in excess of 50°, and some respond best to summer-like temperatures of 70-95°. Here are a few plants to consider for the upper end of the heating scale.
- New Zealand spinach
- Summer squash
- African violet
Supplemental Lighting Options
If you need supplemental lighting for your winter greenhouse, there are several options. Blue light encourages compact, bushy growth, which is preferable for greenhouse gardening, and is good for seed starting. Fluorescents are a good choice here; not only do they produce light on the blue end of the spectrum, they’re cool to the touch, so you can put them close to your seedlings without harming them. Red light, on the opposite end of the spectrum, triggers the hormone response that creates blooms. For general use, a balance of red and blue light is best; this LED panel offers an energy-efficient way to provide that light.
Ventilate for Plant Health
You’ll need to plan greenhouse ventilation each day, even in the coldest weather. Mechanical ventilation by means of circulation fans and greenhouse fans is the ideal solution; but if you don’t have any fans, then opening doors and windows briefly should be sufficient. Just don’t let the interior of the greenhouse get colder than your plants can handle.
Give Them Some Space
Finally, be sure to have enough tables, benches, and shelves on hand, so your plants aren’t sitting on the cold ground, or crowded together. Shelving also provides you the flexibility to move the plants around as need be.
The Bottom Line
The weather may be turning cold, but that doesn’t mean you have to put your gardening plans on ice. You can spend the entire winter growing your favorite plants in a greenhouse, as long as you take a few precautions and provide them with the humidity, temperature, and light they need.