Extending the gardening season

Those of us who garden in the northern U.S. and Canada are forced to take a 3-4 month break from gardening every winter. And few of us actually welcome that break.

Philosophically, we have always accepted this as a time for the garden to rest and recuperate in anticipation of springs arrival. But, some of us don’t want to wait. We do not have to accept this traditional waiting period to get our hands dirty and salads fresh.

There are techniques and devices to allow us to garden year round, despite the weather. Ah, where would we all be without techniques and devices?

And now, with the threat of shorter winters, due to climate change, the ability to garden all the time is even easier.

You are only limited by your own imagination in cheaply creating a sustainable environment out of found or recycled materials to grow all the ingredients for your next salad.

Solar energy is almost always available. How we use it when it is available is the key. If we can protect our plants from winters wind, freezing rain and snow and store this solar warmth, we can pull this off.

For those times when the sun cannot help us, then we must use our imagination to generate heat until the sun does come out.

Extravagant methods involve using heating cable wound throughout a growing bed, installing light sources, and even installing heaters under a protective roof. These require electricity and of course electrical wiring running through the yard that, quite frankly just doesn’t sound very safe.

For simpler, less dangerous methods, read on.

Over the years gardeners have discovered cloches, forcing jars, solar-charged hot water bottles, row covers, cold frames and all sorts of other devices to stretch the growing season by as much as four to six weeks in Spring, as well as in Fall. With a greenhouse, gardening can become an all-year endeavor.

Any of these devices can be made of glass or plastic and they can be purchased or made out of materials you probably use on a daily basis.

Cloches, in their simplest forms, are glass jars. Traditionally bell shaped, they have also been made to look like lanterns and pyramids complete with a metal framework to add a touch of decoration to the garden. You can create the same effect by attaching panes of glass on a wood, wire, pvc or bamboo frame. They were first designed by the French to keep out the bitter cold and frost and to warm up the soil surrounding the plant in spring to hasten their crops to early maturity. They also protect plants from insects, birds and strong winds.

Any clear glass or plastic jar you have in your home can serve the same purpose. You can also use plastic milk cartons, soft drink or juice bottles or any semi-rigid container that will allow sunlight penetration. The larger the better to allow for breathing room. You just need to devise a way to prevent them from being knocked over by the wind. I personally have used landscape fabric anchors of heavy gauge wire poked through the sides of milk bottles and shoved into the ground to anchor the containers. It works pretty well if you anchor them deeply enough.

Cloches come in all sizes and can even be used as terrariums as the ones pictured here.








There are umbrella cloches, which are basically very large cloches, but some are made without sides, or with sides that don’t reach the ground. These can be used in warmer weather to shade individual plants or a small number of plants from an overbearing sun.


In spring, cloches are great for heat-loving plants that are spaced a little further apart, such as tomatoes, peppers and sqaush. You can have tomatoes up to four weeks earlier with these handy devices and this in itself is well worth the effort.

Here’s an example of a home-made cloche using a wire hanging basket and poly film. The film is strong enough to last a few years and is easily replaced if it breaks. Cover the hanging basket with a piece of the film, folding the film over the edge of the rim and then attach it to the frame with cellophane tape. Use a hairdryer to shrink the film until all the wrinkles disappear and it goes tight. Snip off any surplus film with a pair of scissors.

One drawback to most cloches is they have to be constantly monitored and occasionally lifted or propped up to allow the built up moisture and heat to escape. Some cloches you have a lid on top that you can lift off for this purpose.

Another drawback to cloches is they only cover a few small seedlings or individual plants. This led gardeners to create the row cover. Look at it as a continuous cloche. It’s a tunnel-like structure, made of plastic or glass or mesh and supported by wire, wooden or plastic hoops. It can be opened at each end or closed but should be easily opened to allow air circulation and to allow heat to escape. It can also be used throughout warmer weather to act as shade and a barrier against insects and birds.

Forcing jars are used to force bulbs. They are made of clay and do not allow light to enter. Typically they are very use specific for rhubarb and chicory. (picture of forcing jars from blog pictures)



Row covers are constructed of hoops and sheeting available from a variety of sources and are made of materials that can transmit up to 85 percent of available light. Depending on its weight it can keep heat in, bugs out, allow water in and creates a great windbreak. It can be cut to any size frame you have and at the end of the season can be folded for storage. In summer, for shade purposes, there is fabric that can allow up to 70 percent light in for those plants that need more light.

Hot caps are basically simple cloches used in cooler zones to protect seedlings from cold weather and birds. They are made of plastic or a heavy translucent waxed paper. They only provide 2-3 degrees of frost protection so plants can go into the garden 1-2 weeks earlier than without protection.

Wall-o-water are great for protecting from freezing weather and can allow less cold-hardy plants such as tomatoes, peppers, squash up to 6 weeks early start without fear of freezing. These are very easy to make yourself by grouping 2 liter soda bottles around one bottle (or anything else to act as a form) in the center, tape the outside bottles together and pull out the center form to create a donut. Fill the outside bottles with water and set them around individual plants. The sun heats the water during the day and envelopes the plant with heat during the night. You need to place something over the top to help keep the heat in. When the warmer weather arrives, your plants should already be popping through the top and you can remove the wall-o-water.

Cold frames or Sun boxes are usually home made structures of wooden boards, plywood, concrete blocks, or bales of hay with glass, plastic or fiberglass sheeting to act as a lid which is hinged at the back. They are built higher at the back so that when the frame sits on a raised bed or on the ground, the sun can reach into the box to the plants. You prop the window up during the day and close it at night to keep heat in. The optimum size is between 2 by 4 feet and 3 by 6 feet so you can reach all of the plants inside. If you have raised beds it would be ideal to match the size so the cold frame sit on the sides of the bed.

The frame should be facing the south or southeast for maximum sun exposure.

The key to using a cold frame successfully is paying attention to the temperature—and the trick is in keeping it cool rather than warm. The temperature inside the cold frame should stay below 75 degrees F for summer plants, below 60 degrees for cold-tolerant plants like lettuce, carrots, etc. The way to keep temperatures cool inside a cold frame is to lift the lid. A good rule of thumb: when outdoor temperatures are above 40 degrees, prop open the lid 6 inches; when the outdoor temps stay above 50 degrees F for several days in a row, remove the lid. Be sure to restore the lid in late afternoon to trap the heat inside for cool nights. You can also buy automatic venting devices in some gardening catalogs.

On frigid nights, the plants inside the cold frame may need a little extra protection to keep from freezing. Most heat escapes through the glass, so pile insulation on top. You can use old blankets, straw, newspaper or whatever is handy. Snow insulates well, too, but brush heavy snow off the glass so it doesn't break.

These are great for hardening-off seedlings on their way into the open garden.

Hot beds are cold frames heated by soil-heating cables, steam pipes or fresh manure buried beneath the rooting zones of the plants. Everything else is basically the same.

Solar-charged hot water bottles are any water-filled container painted flat black to absorb solar warmth during the day and release it at night. These are stacked at the back wall of a cold frame as a layer of insulation. Use square, plastic milk jugs so they are easy to stack, or you can incorporate black water-filled barrels in any wall of your cold frame’s design. You can also use soft drink bottles and juice containers, simply stack them loosely or duct-tape the cylinders together to build a heat-absorbing wall to give any tender seedlings an earlier start.

Greenhouses are the ultimate in indoor gardening and come in a wide range of sizes and shapes from stand alone to lean-to type to place against your house, garage or shed. They are constructed of plastic, glass, or fiberglass with the frames made from metal, wood, plastic, bamboo, or pvc pipes. The panels are sometimes doubled up with a layer of air between them as an extra measure of insulation. There is a huge market for all of the accessories you could possible need or want for a greenhouse, from potting benches to heating and ventilation elements. These are pretty impractical for the smaller yard but if you have the space then they can provide a great way to grow year round.

Winter sowing is the latest method of seed germination. Aside from the typical method of starting your seeds indoors, this method takes place outdoors. You create mini-greenhouses out of containers such as gallon plastic milk cartons, 2 to 5 gallon water bottles, two-liter soda bottles, salad take-out containers, and big plastic jars (the kind pretzels come in at warehouse clubs) . These containers should be large enough to hold about 3 inches of soil and have enough head room for the growing plants.

Punch holes in the bottom of the containers for drainage. If the opening of the container is small, cut the top off to allow access to the inside. For convenience in lining it back together, leave part of it attached to use as a hinge, add soil and then wet it good. At this point it is best to allow the water to drain well and add the seeds later. After adding the seeds, tape the two halves together and set the container outside in the sun. Keep checking your containers for condensation, if there is none then it means you either have too many holes in the lid or the soil is drying out. Water as often as is necessary to keep the soil moist but not soggy.

If you are using large mouth jars then punch holes in the lids for ventilation, for small mouth containers don’t bother, just throw the caps away.

As the weather warms up in spring, make your transpiration holes larger until you can take the lids off entirely. This process is the hardening off period and after this is completed simply take your plants out of their containers and put them into the open garden.

You could actually put your seeds in jiffy pots inside these containers so you do not disturb the roots when you transplant them.

Virtually any seed you can start indoors will work for this winter-sowing method. So experiment, the materials are all re-useable so it doesn’t cost much to try.

Before you know it we will all be eating fresh salads from our very own garden year round.

All of these devices work very well for non-edible plants as well so don’t be afraid to experiment. Part of the joy of gardening is discovering the little tricks that help make you a more successful gardener.

Happy gardening to you!