Winter Greenhouse Gardening In a Growing Dome®

Outside, the garden beds are frozen. Snow settles across the landscape. Trees stand still and bare. Inside a Growing Dome, it feels like a different season entirely.

Winter greenhouse gardening transforms the coldest months into a slower, quieter, but still productive time of year. Instead of shutting down when temperatures drop, the dome creates a protected microclimate where plants continue growing, often without supplemental heat, even when outdoor conditions fall well below freezing.

For many Growing Dome gardeners, winter doesn’t mean stopping. It simply means growing differently.

Gardener harvesting winter greens in greenhouse with snow built up outside visible through the polycarbonate

How Winter Greenhouse Gardening Works

The Growing Dome captures low-angle winter sunlight and holds onto that energy efficiently. During the day, sunlight warms the air, soil, and water inside the structure. At night, stored heat is released gradually, softening the temperature swings that damage plants outdoors.

Preparing the dome for colder weather helps everything work even better: growers often adjust ventilation, seal gaps, and insulate vents and openings ahead of winter so heat accumulates more effectively and stays inside longer.

Several elements make this possible:

Passive solar gain through the polycarbonate glazing
Thermal mass from the above-ground pond
Insulation in the foundation wall and on the reflective north wall insulation reduces heat loss
A geodesic shape that sheds snow and resists wind

Water plays a major role. As thermal mass, it absorbs heat during daylight hours and releases it overnight, helping regulate the interior environment.

Because of this integrated design, the Growing Dome typically requires up to one-third less energy than a traditional greenhouse, while maintaining productive growing conditions year-round.

The goal isn’t tropical heat in January. It’s protection, moderation, and efficiency.

42 foot diameter growing dome with red door covered in a light layer of snow

How Warm Does a Growing Dome Stay in Winter?

Gardeners naturally want to know what kind of temperature difference to expect. In climates similar to Pagosa Springs, Colorado, with sunny, high-elevation, cold winters, a Growing Dome is typically 20–30°F warmer than outside ambient temperatures.

That means:

When it’s 20°F outside, it may be 40–50°F inside
On clear winter days, temperatures often climb higher
At night, thermal mass slows the rate of cooling

Performance varies with sun exposure, insulation, wind, snow cover, and overall setup. That temperature advantage often provides the margin that allows cold-hardy crops to remain productive through winter.

Pro Tip: Let Snow Work for You

Snow management plays an important role in winter performance. Clear snow from the south-facing side of the dome to allow maximum sunlight to enter. As snow naturally sheds off the structure, allow it to accumulate along the north side, where it acts as natural insulation and helps reduce heat loss.

Used intentionally, snow becomes an asset rather than an obstacle.

Growing Dome greenhouse surrounded by snow with a light dusting on the polycarbonate panels

To Heat or Not to Heat?

One of the most common questions is: Do you need to heat a greenhouse in winter?

In a well-oriented Growing Dome with sufficient thermal mass, many cold-hardy crops grow successfully without supplemental heat. The passive solar design and 20–30°F temperature advantage often carry leafy greens and root vegetables through the season. However, every climate and growing goal is different.

Supplemental heat may support:

Warm-season crops like tomatoes, peppers, citrus, or orchids
Pond plants or fish
Protection during single-digit overnight temperatures
Regions with extended cloud cover
An added margin of security during extreme cold snaps

Before installing mechanical heat, many growers use low-tech protection methods such as row covers, frost blankets, or Walls of Water around individual plants. These tools create small insulated air pockets that reduce overnight stress without raising the temperature of the entire greenhouse.

Some growers heat only during the coldest stretches of the year. Others install thermostatically controlled backup systems for additional assurance.

Gardener overlooking a Growing Dome greenhouse garden with row cover around the perimeter beds

Interior of greenhouse with plants covered in frost cloth, a fan shutter, a green watering can, and snow visible on the outside

Young chard plants and beet greens with deep red tinted leaves surrounded by row cover

Choosing the Right Type of Heat

Heating systems influence humidity as well as temperature. Combustion-based heaters, such as propane, produce heat along with water vapor. The added moisture increases interior humidity and may contribute to condensation during cold weather.

Electric heaters generate dry, non-combustion heat, warming the air without adding moisture. Wood stoves also provide relatively dry heat when properly installed and ventilated.

Balanced airflow and moisture control are essential parts of winter greenhouse management. Heating decisions are influenced by your crops, climate, and comfort level. For many growers, passive solar performance carries most of the winter load, with supplemental heat reserved for extreme conditions.

Propane bottle with tank top two burner heater

Electric greenhouse heater hanging from wooden strut

Wood stove with door open in a geodesic greenhouse

“I have a number of friends here in Pagosa Springs, Colorado, who have chosen not to heat their Growing Dome greenhouses. I have only heated my personal 22′ Growing Dome for one week in 15 years…” — Udgar Parsons, Growing Spaces Founder

Man and woman seated under a pergola inside their Growing Dome greenhouse

“Today’s high was 21°F, and tonight will likely be in the minus teens… If we didn’t heat, the fig trees would survive… but all pond plants would die.” — Heather Gray, Growing Dome Gardener and Educator

Woman smiling while watering winter crops in front of a pond in a greenhouse

What Thrives in a Winter Greenhouse

Winter favors resilient, cold-hardy crops. Most successful winter greenhouse vegetables are planted in late summer or early fall so they are established before cold weather arrives. Fast-growing greens can be planted later, while most plants benefit from strong root systems before daylight hours shorten. For more information about recommended timing for starts, check out our planting schedule.

Leafy Green

Lettuce, Arugula, Swiss Chard, Spinach, Tatsoi, Mâche (Corn Salad)

Brassicas

Bok Choy, Broccoli, Cauliflower, Kohlrabi, Brussels Sprouts, Cabbage, Collards, Kale, Mizuna, Mustard Greens

Roots

Turnips, Radishes, Carrots, Beets, Parsnips, Rutabaga

Herbs

Rosemary, Cilantro, Dill, Parsley, Sage, Thyme, Oregano

Alliums

Chives, Green Onions, Leeks

Others

Celery, Celeriac, Peas, Fennel, Strawberries

Gardener holding a harvest of winter greens standing in front of a 15 foot diameter growing dome greenhouse

Winter Growing, Made Practical

Winter greenhouse gardening in a Growing Dome is about turning possibility into something dependable.

With passive solar design, thermal mass, proper winterizing, and crops suited to shorter days, the Growing Dome creates a stable environment where growing doesn’t stop when winter arrives. Snow adds insulation. Light drives the system. Heat, when needed, is used intentionally but not relied on.

The result is a greenhouse that supports steady harvests, lower energy use, and a year-round connection to fresh food, even in cold and snowy climates.