Where Do I Locate My Cold Frame?
There’s no simple answer to this one. The best location for your cold frame depends on your geographic location, the season, and the way in which you use your cold frame. Happily, the Carnival Gardens cold frame is portable and easily disassembled, which means you can change the location of your frame from time to time or season to season to best suit what you’re doing at that moment.
Begin your quest for an appropriate location by remembering that cold frames really shine during the early and late season – that critical time before frost date. Getting the right amount of light and warmth into your cold frame is the priority. That said, a gardener living in Pacific Washington has different hot/cold patterns and different afternoon temperature differentials than someone living in Southern Arkansas or Western Colorado.
The first rule of thumb is that you should avoid putting your cold frame in a low spot in your yard or garden. Cold air sinks, making low spots frost magnets. (Cold frames will protect your garden down into the 20’s without any additional heating – but why take chances?) If you place your cold frame against a house or a shed, you’re almost guaranteed to keep from putting your frame in a low spot, as most houses are designed to drain water away from the house. This little feature also “drains” cold air away from the house and your cold frame.
Now: on to the sun. You want some of it – maybe even a lot of it – but not too much of it. The problem is the afternoon sun. It’s the hottest sun of the day, and will have the most influence on the plants inside your cold frame. Southeast orientations are very useful and the easiest to recommend, because you can get the temperature of the cold frame to raise in the critical morning hours. It’s often coldest just before dawn, and getting the first early morning light rays into your frame will keep your plants happier and warmer.
If you put your cold frame on the southwest-facing wall or corner of a structure you may get too much solar gain. During other times of year, you could rely on trees for shade, but in the post-frost, pre-frost landscape, your deciduous trees will have lost their leaves. (Remember this when you’re siting your cold frame!) Evergreens work or deciduous bushes that are brushy (forsythia, etc.) come to mind. You may even have to devise some kind of shading system to keep sun off your cold frame in the afternoon.
If you’re using your cold frame to grow vegetables and greens (beets, carrots, chard, arugula, lettuce, etc.) after their normal growing season in the Fall, you may be well-served locating the frame in a sunny, protected location with a 100% southern exposure. That will pump in the maximum amount of light and warmth to keep your vegetables growing happily for many weeks past your local frost date.
That’s been my most common setup in the past – cold frames set against south-facing house walls. The south-facing walls can trap a lot of heat and light during the day and the thermal mass of the wall can help keep temperatures up at night. I’ve had problems with heat buildup – especially in the late spring – when it’s really sunny and warm. Cloudless days and a big white south-facing wall can really drive up temperatures inside the frame. If you have the same problem, remove the top from your cold frame. You’ll get some wind protection at ground level for your plants, and you won’t get the same heat buildup.
Some situations may call for placing the cold frame directly in the garden. Maybe you want to try getting tomatoes in the ground very, very early. Planting six tomato plants inside the cold frame and putting the entire cold frame in the garden will help warm the soil and protect the young tomato plants. The water-filled miniature tomato greenhouses will give your tomatoes a few extra days of head start, but using a cold frame will warm more soil during the day, giving your tomatoes an extra edge.
Like most gardening activities, there aren’t wrong answers, just more right and less right answers. Enjoy your search for a perfect cold frame location!