What's blooming

Rodger Whitlock totototo@telus.net
Thu, 23 Feb 2012 17:19:55 PST
On 22 Feb 2012, at 18:18, Sujit Hart wrote:

> I am new with this group. When you mention cold frame, what exactly are you
> refering to? It seems all of you have one in your back yard. 

Essentially a topless, bottomless wooden box covered with glass or transparent 
or translucent plastic.

You wouldn't think so, but even such a simple affair can give a surprising 
amount of protection from winter cold, thanks to the earth itself acting as a 
source of heat - not high temperature heat, but heat nonetheless.

In addition, a coldframe offers protection from rain, important in winter-
rainfall climates like the Pacific Northwest.

Covered with a screen in warmer weather, a coldframe can also keep flying pests 
at bay, notably narciussus flies.

Another benefit is that in summer a coldframe keeps the sun off the sides of 
pots in it and prevents the soil in the pots from overheating. This is why many 
nurseries corral their potted plants in areas surrouned with low walls of 
masonry or wood.

You can make coldframes of any convenient material, but my experience is that 
once you have a little experience with them, it's a good idea to draw up a 
fixed design instead of cobbling them together from whatever is handy. This 
mostly affects the cover: should it be old windows, or something made to 

A bulb frame is a little different, usually referring to a masonry raised bed 
containing pots plunged in sand, but invariably covered with barn cloches or 
something similar that gives the plants some head room when they flower in 
early spring (typically).

Rodger Whitlock
Victoria, British Columbia, Canada
Z. 7-8, cool Mediterranean climate

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