Extending the Growing Season with Cold Frames Workshop


Global Awareness Local Action (G.A.L.A.) and Jack Mountain Bushcraft School are excited to announce the next feature in their 2015 monthly NH Re-skill-ience Workshop Series, hands-on workshops focusing on homesteading, sustainable living, and traditional bushcraft skills that strengthen personal and community resilience.  The next workshop, Extending the Growing Season with Cold Frames, with Josh Arnold takes place on Wednesday, August 5th from 6pm to 8pm at Three Pork Hill in Ossipee, NH.


A cold frame is essentially a bottomless box with a covering of glass or clear plastic sheeting. These coverings are called “lights” because they collect the warm sunshine to heat up the plants contained inside the frame. If you construct a moveable “box” it can be placed directly over a portion of your garden bed to protect plants that are growing in the ground.  Otherwise you can build a permanent cold frame to plant specific hardy crops.

Cold Frames gives growers a jump on spring planting and a longer harvest in the fall.  In the spring they provide a place to start seedlings and in the fall they provide additional thermal collection and weather protection.  Even in the summer crops can be grown in the open frames where they are protected from winds and can grow faster than unprotected crops.  Those who have harvested and eaten a salad of fresh greens in February or have flowers blooming well past frost, know the attraction of using cold frames.  There are many different ways and methods of using cold frames including overwintering dormant plants, giving seedlings an early start, hardening off young seedlings, and extending the season past frost.

Workshop participants will learn about design considerations, cold frame maintenance, and which hardy crops do well in cold frames.  Participants may choose to come simply to learn about the cold frames or for an additional materials fee they can build a cold frame onsite to take home.


Extending the Growing Season with Cold Frames workshop takes place from 6:00pm to 8:00pm, at the G.A.L.A.’s office located at 3 Pork Hill Rd., Ossipee, NH.  Admission for the workshop is $15.  If a participant would like to construct and take home a cold frame there is an additional $30 materials fee. Register below or call 603-539-6460 for more information.

Here are ten important cold frame considerations:

1. Location: Place in a spot that receives ample amounts of sunshine. A south-facing wall works best. The ideal location is also slightly sloped to allow water to flow away from the cold frame.

2. Protection: Consider placing against an existing structure (home, garage, fence, etc.) A home will add warmth, but the main thing here is protection from wind and other elements.

3. Soil: Prepare topsoil by sifting out unusable rocks, grass, etc. Aerate the sub-soil with a pitchfork. Mix compost in.

4. Insulation: Set the cold frame into the earth a bit for added insulation. If there are multiple days below freezing, throw old blankets or burlap bags on top of the cold frame. Uncover when the sun arrives. You can also use polystyrene sheeting along the inside walls. Bubble wrap can also be placed on the inside window.

5. Material: Use cement blocks or untreated wood that will not decompose, such as cypress, cedar, or hemlock.

6. Size: 3-4 feet is a good width for a cold frame. Anything larger will make it difficult to harvest back rows. Popular dimensions are 3’x6’ and 4’x8’. A minimum height of 8” is desirable (12” is better).

7. Structure: Build the frame to fit the window, higher in the back than the front. Add weights to keep the window sashes from blowing open during strong winter storms.

8. Propping: During days of over 45 degrees, include a way to prop open the window for ventilation.

9. Reinforcement: Use wooden or metal stakes to abut the sideboards for increased rigidity.

10. Moisture: Be sure to check soil moisture and keep beds properly watered, as the evaporation process is quickened with a cold frame.