The Basics of Cold Frame Gardening


Interested in utilizing a cold frame garden bed for planting? Find out everything you need to know about cold frame gardening in order to benefit from these backyard structures.

What is a cold frame?

A cold frame garden bed is an unheated structure used to house, protect, and harden off seedlings and small plants. Whether glass or plastic, these units rely solely on the sun for internal heat in order to provide a slightly warmer environment and a level of protection from external weather.

BioStar 1000 Premium Cold Frame

Cold Frame Gardening Benefits

Extend the Growing Season.

Cold frames provide a slightly more controlled environment for plants. This is particularly beneficial early or late in the season and for those exposed to colder climate conditions when unexpected frost or the unseasonably warm weather is common and can impact delicate plants and seedlings. With a cold frame, you safely get a head start on crops and extend your fall harvest by weeks.

Overwinter plants.

You don’t have to start from scratch with brand new plants at the beginning of every gardening season. Cold frames are great for overwintering dormant plants, offering a protective home during the offseason. As long as the soil stays moist and sunlight is minimized, plants remain dormant and sheltered in order to easily grow come springtime.

Harden off plants and seedlings.

Many gardeners start plants indoors before moving them to the garden. Whether in a planter in the house or in a greenhouse, it can be awhile before the weather is temperate enough to make such a transition. Cold frames help plants adjust more easily to the change in temperature, sunlight, moisture, and exposure outdoors. They often include latched windows you can open and close in order to slowly and steadily expose plants to the outdoor climate.

Year-Round Cold Frame by Juwel

Tips for Cold Frame Gardening

Choose your ideal cold frame.

Cold frames are typically low structures you place over the soil or some options include a raised bed (such as this one!). Determine whether you want to plant in the ground or within your bed, and ensure plenty of space for whatever you decide to plant. Check out our selection of cold frame beds here.

Cold frames work best for cool-season plants.

Cold frames work great for starting cool-season plants early. These plants germinate in colder temperatures, so they don’t require as much climate control as a greenhouse provides. A cold frame will help keep them safe and growing ahead of schedule.

If you decide to place warm-season seeds in your cold frame, start them a week or two before their average last frost date. But, be cautious with these tender varieties, as cold frames only provide so much protection against extreme weather conditions. Consider utilizing a standard greenhouse for the more sensitive plants and seedlings and a cold frame for only briefly transitioning plants.

Maintain your cold frame to successfully acclimate plants.

Because of the design of a cold frame, the internal temperatures can drastically fluctuate if not maintained. Even a cold frame can become as warm as a greenhouse if kept shut on a hot, sunny day. These structures serve to protect delicate plants whether within transition or at the beginning/end of their season, so it’s important to regulate sun exposure and heat inside.

When hardening off plants in your cold frame, make adjustments throughout the season in order to successfully transition plants and keep delicate seedlings safe. Consider starting your cold frame in a shady location before exposing plants to a full day of heat and sunlight. Or on unexpected warmer days, open up the latch to allow extra airflow to prevent plants from overheating. Such small accommodations throughout your cold frame gardening experience will allow plants to more easily adjust to the outdoors.


Utilize a cold frame garden bed for extending your growing season and provide a safe home for seedlings or transitioning plants. These economical, compact gardening solutions help support your gardening experience and improve the health and growth of your greenery. Shop for more gardening solutions here at for year-round planting made easy.

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