Home > Vegetable Gardening > Season Extenders for Vegetables

Season Extenders for Vegetables

By: Lynn Jones - Updated: 2 Mar 2013 | comments*Discuss
Season Extenders Vegetables Garden

In climates with short growing seasons, season extenders such as cloches, cold frames, tunnels and greenhouses are a great way to extend the growing season.

The Advantages of Season Extenders

Season extending structures help gardeners get an early start on spring planting. Tender vegetables such as tomatoes and peppers can be planted earlier and covered if a late spring frost is predicted. Late season vegetables such as winter squash or still-ripening tomatoes can be covered in the autumn in case of an early frost. Season extenders can also enable gardeners to plant later in the season and prolong harvests through late autumn or even into winter.

Garden coverings such as cold frames are also used to “harden off” seedlings started indoors. Putting them in a cold frame before planting them in the garden acclimatises them to outdoor weather.

Other Benefits

Season extenders can also be used to warm up the soil in the spring. While black plastic is commonly used for this purpose, cold frames or a row of cloches will work as well. Season extenders also retain moisture and may reduce the need for watering. They can also protect from harsh winds and cold rain.

Coverings can also be used to prevent insect infestations and to protect plants from birds, rabbits and other crop-eating pests.

Simple Coverings

The simplest way to protect just-planted crops from a spring frost is to cover them by hilling up soil around them. The young plants will still emerge through the soil once warm weather returns. This method is useful with early potatoes, for example. Other easy coverings include loose straw, dry leaves or a layer of compost.

Another simple solution is to cover a newly-planted row with tarpaulin, newspaper or other thin layer to protect against an overnight frost. Use rocks, bricks or soil to weigh down these coverings to prevent them from blowing away.

Cloches and Tunnels

Cloches have been used for centuries – one well-known example is the Victorian bell jar. The purpose of a cloche and other season extenders is to trap the heat of the sun’s rays, creating a warmer environment for the plants underneath.

A cloche works using the “greenhouse effect”. The sun’s short ultraviolet rays pass easily through the glass, warming the air and soil underneath. Within the cloche, the ultraviolet rays are converted to heat in the form of longer infrared rays, which pass back out through the glass more slowly. Soil, in particular, is a good heat collector, maintaining the heat within the cloche and releasing it slowly throughout the day and night. Note that if temperatures are too low or there is little sunshine, cloches will not produce this effect.

Cloches may be made from glass or plastic. Glass traps the heat better than plastic, but requires careful handling to avoid breakage. Plastic is inexpensive and less breakable, but does not trap heat as well.

Cloches may be dome-shaped, conical, or bell-shaped enclosures for individual plants. They may also be tunnels, or continuous cloches, which cover an entire row of plants. Continuous cloches can be tent- or barn-shaped glass structures; rigid plastic tunnels; or polythene (polyethylene) over flexible hoops. Cloches and other season extenders must be ventilated to prevent too much heat buildup.

Cloches can be purchased or homemade. A recycled plastic drink or milk container with the bottom cut out is one option. Taking off the cap provides ventilation. A glass cloche can even be made from a large wine bottle by cutting off the bottom using a glass cutter and sanding the cut edge with emery paper. A tomato cage or hardware cloth covered with plastic is another idea.

Cold Frames

Cold frames are like mini greenhouses. They can be purchased or homemade. Cold frames are often made using old wooden windows, but clear plastic can also be used. Cold frames may be permanent or portable. A permanent frame can be made of bricks or rocks, both of which hold heat well. A portable frame can be made from lighter material such as plywood or bales of straw. The glass cover is best positioned at least a 45 degree angle, facing south. Double cold frames use two lids with a hinge, like a row of glass-roofed houses.


While cold frames are relatively inexpensive, greenhouses can be a major purchase. Greenhouses may be made of panes of glass or rigid plastic framed in timber, aluminum, or plastic. Another variation is the hoop-style greenhouse. Greenhouses are often heated to further extend the growing season.

Try a few of these season extenders to stretch your gardening season and boost your harvests!

You might also like...
Share Your Story, Join the Discussion or Seek Advice..
Why not be the first to leave a comment for discussion, ask for advice or share your story...

If you'd like to ask a question one of our experts (workload permitting) or a helpful reader hopefully can help you... We also love comments and interesting stories

(never shown)
(never shown)
(never shown)
(never shown)
Enter word:
Latest Comments
  • Robyn
    Re: Growing Squash and Pumpkins
    @Freemind - They will happily grow on a teepee type arrangement. They are fine growing up high, you can stablise them if you thing…
    17 July 2018
  • Freemind
    Re: Growing Squash and Pumpkins
    Was given some onion squash seeds. Have four successful plants 3 of which have squash growing on them. I put up sticks because they…
    16 July 2018
  • Kamel
    Re: Everything You Need To Know About Brassica Vegetables
    search for any work i am agricultural engineer vegetables and foods
    22 June 2018
  • ella_TP
    Re: Growing and Using Artichokes
    Artichokes are best planted as began seedlings in trenches eight inches profound, fixed with one inch of fertilizer or decayed…
    26 February 2018
  • Rabby
    Re: Pickling Onions and Shallots
    I've been doing my own pickled onions for myself and my family for 30 years and I di them the same every year . I have about 10 of…
    16 February 2017
  • MrsF
    Re: Pickling Onions and Shallots
    I've done my 1st jars of onions today using 1/2 a 4kg pack of Parrish's onions. I'm using Sarsons pickling vinegar with…
    30 October 2016
  • Silverfox
    Re: Pickling Onions and Shallots
    When making a brine for pickles you need a tablespoon of salt for every pint of water, leave pickles in for no more than 24hrs. 3…
    28 October 2016
  • Pickles
    Re: Pickling Onions and Shallots
    I live in Spain and am having great difficulty in buying pickleing onions, anyone got any idea where I can buy them as I need…
    16 October 2016
  • Ian
    Re: Pickling Onions and Shallots
    Hi, I am in the process of doing some pickle onions. Yesterday I made a brine solution with approx 5 ltrs water and went a bit…
    5 October 2016
  • Minety15
    Re: Pickling Onions and Shallots
    Hi, I've been given a jar of pickled shallots and they are soft, does anyone know if it's possible to crisp them up again…
    30 September 2016
Further Reading...
Our Most Popular...
Add to my Yahoo!
Add to Google
Stumble this
Add to Twitter
Add To Facebook
RSS feed
You should seek independent professional advice before acting upon any information on the VegetableExpert website. Please read our Disclaimer.