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8 Colorado Experiment Station 
For temporary cold frames the low frames are simply set on the 
ground where the soil has been made sufficiently rich for growing 
plants. The frames are made the same as for hotbeds. Cold frames 
are covered with! glass sashes, oiled paper, canvas, or muslin dipped 
in linseed oil and dried. Glass sashes are best for cold weather, but 
in the latter part of spring when only a few degrees of frost are had, 
one of these substitutes may be used. 
Uses oe Cold Frames 
Cold frames are used for maturing crops late in the fall, for carry¬ 
ing over winter young plants such as cabbage and cauliflower for 
planting in the spring, for protecting semi-hardy flowering plants dur¬ 
ing the winter, for starting plants before the weather is warm enough 
to plant the seed in the open, and for hardening off before planting 
in the open young plants grown in the hotbed or greenhouse. Occa¬ 
sionally permanent cold frames are used as storage pits for vegetables, 
such as celery, cabbage, potatoes and root crops. 
For starting plants in the cold frame the seed is sown either in the 
soil or in flats or pots and set within the frame. Young plants are 
sufficiently protected from the cold to prevent freezing, as they be¬ 
come hardened enough to withstand light frost. When the weather is 
mild enough, the plants are transplanted into the open. 
A very common form of temporary cold frame in the south con¬ 
sists simply of two parallel rows of planks set up in the! field six feet 
apart and covered with sashes. The seeds are planted in thein regip- 
lar rows between the planks, and when the weather is warm enough 
the sashes and boards are removed, leaving the plants well started in 
the field. This process may be reversed in the fall, starting the plants 
in the open and later putting up the frame to protect them. 
Semi-hardy flowering plants like pansies and geraniums are put in 
cold frames for winter protection. Usually two or three inches of sand 
or cinders are put in the bed and the pots sunk into them. 
