How to Build a Cold Frame or Hoop House
Looking for an inexpensive way to extend your garden season? Maybe you can’t afford a full greenhouse with heating, ventilation, and all the latest gadgets. Or maybe you’re only looking for a short timeframe to extend your harvest by a few weeks? A cold frame or hoop house may exactly what you need. Let’s look at how to build a cold frame or hoop house.
What is a Cold Frame?
A cold frame is an unheated space out in your garden. It may be sheltered against a building, or free-standing. Usually the top of the cold frame is clear glass or plastic to allow the sun to heat the space. it is called a “cold” frame because there isn’t any other source of heat. The sides may be wood, brick, stone, metal, dirt, or any other material you have handy. Cold frames usually face south with the higher edge to the north. This allows sun to come in through the glass at the right angle to heat the space.
You can build a quick and easy cold frame by making a box and putting an old window on top. Adding hinges or hooks can make the glass easier to adjust, but are not necessary. If the temperature gets warm during the day, you will want to be able to prop up the south edge of the window to allow some ventilation. Small cold frames can heat up quickly and cook your plants if you’re not careful. Cold frames are great to protect cool season veggies from hard frost or snow and can extend your season for weeks. Some well designed cold frames can keep kale or other hardy veggies going all winter long.
What is a Hoop House?
A hoop house is usually a low tunnel of plastic or frost cloth set up directly over a garden bed. Some are big enough to walk through, but most are low to the ground, just to protect the plants. The “hoops” are flexible rounds of wire or plastic that holds the protective material up off of the plants. The material is usually clear or translucent to allow sunlight to warm the hoop house and keep the plants growing.
You can build a quick and easy hoop house by driving short lengths of rebar into the ground on either side of your garden bed. Then curve lengths of PVC conduit from one rebar stake across the bed to the other. Cover these hoops with plastic or frost cloth, bury the edges, tie off the ends, and your hoop house is ready to grow. You can use hoop houses for season extension, shade in hot weather, or for pest protection during the growing season. Hoop houses don’t typically stay as warm as a cold frame, so are usually used for short-term season extension in cold climates.
Should I Build Permanent or Temporary?
When you’re deciding how to build a cold frame or hoop house, you need to consider how long you plan to use it for. A permanent cold frame can take up space that you can use during the growing season. But, spending some time perfecting the design can make it much more effective. If you don’t have indoor growing space and live in a cold climate, investing in some permanent hoop houses or cold frames might make sense. However, if you don’t have much garden space and only need a few weeks of season extension, slapping together some temporary structures may be more cost effective.
For a permanent design, consider where to put your cold frame carefully. Good sun exposure, proximity to your living space for harvesting, and size and shape of materials are key considerations. You don’t have to build your cold frame on an existing garden bed. Nestling it into a sunny corner right outside your door could give you a great space for some salad greens or herbs. You can even build a cold frame on a deck or patio. Be sure to make it deep enough to hold enough dirt or containers.
Permanent hoop houses can be great for brassica family crops that can start early, need protection from cabbage moths during the growing season, and can stay in the bed well into the fall or winter. If you plan to make your hoop house permanent, invest in some good plastic or fabric to make sure it can withstand UV rays, wind, and weather. Spending a little more now will save you time and headaches in the future.
Next Steps
So, if you’re ready to start planning some season extension space into your garden, figure out how to build a cold frame or hoop house that works for you. Decide how much space you need. Consider if it will be temporary, permanent, or a mix of the two. Calculate the cost of your materials and if you can repurpose anything you have on hand. Find some suitable locations, and get building. Soon you’ll be harvesting from your latest garden space and enjoying your extended harvest. Good luck!
Looking for more than just a cold frame or hoop house? If you’re thinking bigger or more tropical, check out my blog post on How to Design a Greenhouse. It’s got all the tips and tricks you need to get started. Enjoy!
Would you rather garden indoors but haven’t had success? Check out my Crazy Easy Containers guide to get you started on an indoor garden paradise!
