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When the days start to shorten and night temperatures dip, do you
often look over longingly at your neighbour's greenhouse, wishing
you too could keep plants producing into the fall? Investing in a
greenhouse, especially a heated one, is an expensive step. For
those of us who aren't quite ready to make the leap, there are a
number of inexpensive options to protect plants from wintry
weather.
Cloches and cold frames can help extend the harvest of summer
crops into fall, keep cool season crops growing through the
winter, and help plants get a good start in the spring. They can
protect plants from moderate frosts, and increase daytime
temperatures by 5-20 degrees F.
Cloches
Originally, cloches were constructed out of glass bell jars and
were used to protect individual plants. However, glass is fragile
and expensive. You can make similar cloches out of plastic pop
bottles or milk jugs. Cut off the bottoms, take the lids off, and
place them over individual plants.
If your plants are too large or you have just too many you can
adapt this method. A cloche can also be constructed using *" PVC
pipe and sheets of plastic at least 5 feet wide and about 10 feet
long. Cut 4 pieces of pipe into 5-foot lengths (angle the cuts)
and bury each end into the soil at least 6 inches so that you
have what looks like a series of crochet hoops. Space each pipe
about 3 feet apart and then drape the plastic over them. You can
secure the plastic by weighing down the ends with bricks or rebar
or clip the plastic right to the pipe with large bulldog clips.
Alternatively, you can use 10-gauge wire instead of the PVC pipe.
Cold frames
Cold frames are very much like mini greenhouses but with solid
sides. They can be constructed using storm or sash windows and a
simple wooden box or bricks for the base. No bottom is required
which enables you to just lift the cold frame and move it around
your garden. One trick to keep in mind is to make sure that the
back of the box is about a foot higher than the front so that you
can angle the lid and take advantage of as much sunlight during
the winter and early spring.
Floating row covers
Floating row covers, often sold as Reemay or Agrofabric, are made
of spun-bonded polyester or spun-bonded polypropylene. The fabric
allows light, water, and air to move through but enables you to
have 2-8&frac; of frost protection. The row covers are available in a
variety of weights but for frost protection, 0.5 ounces per
square yard is the minimum requirement.
Although the fabric is light enough to "float" over your plants,
winter winds can cause abrasion so the cover should be supported
with wire hoops or short stakes. To prevent the cover from
blowing away, the ends should be weighed down with stones or
buried right into the soil. Remember to leave enough slack to
allow room for your plants to grow.
The lifespan of the row cover is usually 2 seasons. When the
fabric becomes a bit too ratty, use it to help germinate seeds.
Placed over bare soil, row cover fabric acts as a mulch, keeping
the soil moist and raising the soil temperature slightly. Seeds
germinate very well in these conditions.
There are few points to keep in mind before deciding which method
of season extension to choose.
Temperature differences - plastic will raise temperatures much
higher than row covers. While plastic is great for winter
lettuce, cool season crops like cabbage and kale don't need such
high temperatures.
Materials - not all plastics are alike. Make sure the material
you use is UV treated and at least 3 mil. thick. Non-treated
plastic will degrade and crack within just one season.
Moisture - If you use glass or clear plastic over your plants,
remember that water doesn't come through and they will need
watering from time to time. Floating row covers don't have this
problem.
Ventilation - On sunny days in the early fall, it's easy for
temperatures within cloches and cold frames to go up more than 20
degrees over ambient temperatures. Ventilation will not only keep
temperatures moderate, but it will also help bring down humidity.
About The Author: Arzeena Hamir is an agronomist and President of Terra Viva Organics.
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