Garden Greenhouses and Cold Frames

A GREENHOUSE: TO BUY OR NOT TO BUY?

Unless you’re lucky enough to have moved into a house with a greenhouse already in place in the garden (or on an allotment), it’s worthwhile pondering the pros and cons of buying one. You need to consider, apart from the cost, the maintenance required, especially if you choose a wooden-framed greenhouse rather than the relatively maintenance-free aluminium models available.

Propagating your own plants and growing plants from seed can be really rewarding and exciting, but you will have to put in a lot of time, effort and money, in order to site and maintain the greenhouse properly. Costs include:

  • CONSTRUCTION
  • STORAGE
  • VENTILATION
  • SHELVING ARRANGEMENTS
  • INSULATION
  • SECURITY

You will also have to thoroughly clean out your greenhouse at the start of each growing season, to eliminate bacteria, mildew and insects.

On a more encouraging note, if you do go for a greenhouse, you will get well ahead with propagation and planting, and will increase your yield of earlier, fresh vegetables, fruit and flowers. You might even allow yourself a few moments of smugness, when you show off your home-grown peppers, tomatoes, exotic fruits and plants!

COLD FRAMES

Cold frames are invaluable for overwintering vulnerable plants, if you do not have a greenhouse – and, of course, they’re infinitely cheaper. Even greenhouse owners find them useful for hardening off seedlings before planting out.

You can either buy cold frames in kit form or build your own. Traditionally, they are made with wooden, aluminium or even brick-walled frames.

Aluminium frames are usually glazed all the way to the ground, so they let in the maximum of light, essential for sturdy growth. Unfortunately, this also means that the frames lose heat quickly through the glass sides, so you will need to insulate them in winter if you want to carry on using them successfully.

Wooden frames are not quite so readily available in kit form, but are popular because they blend in with the garden surroundings better than aluminium frames. If you build your own, go for a simple structure with at least two removable, window-shaped covers that are heavy enough to resist the wind but not likely to give you a hernia when you have to lift or slide them off. Brick-walled frames are, of course, harder and more expensive to construct, but they can look very attractive and the solid structure gives much greater protection to plants than thin-walled frames.

 

INSULATION AND VENTILATION

If you need to give your plants more protection in winter and you have an aluminium and glass cold frame, insulate the sides with expanded polystyrene tiles. Cut the tiles to a snug size for fitting inside the frame. If you cut the tiles too small and they are loose inside the frame, use card wedged in at one end to hold them in position.

Never insulate the top of a frame permanently, unless you use bubblewrap, because plants need as much light as they can get. When very cold nights are forecast, cover the top of the frame with old carpet or other warm, insulating material. Make sure you do this before the temperature drops too low and remove the cover the following morning, unless the temperature remains low.

In warm weather (and sometimes in winter) good ventilation is vital. Frames with sliding tops come into their own here, as they limit the plants’ exposure to potential wind damage.

If your lifting tops do not have an adjustable opening device, make your own wedge from a simple piece of wood. Cut two or three notches into it, to allow you to open the top by increasing amounts as your plants gradually harden off.

26. February 2015 by Dave Pinkney
Categories: Greenhouse Equipment, Greenhouse Gardening | Tags: , , , , | Comments Off on Garden Greenhouses and Cold Frames

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