48 DREER’S VEGETABLES UNDER GLASS. 
the roots have started to grow the plants are comparatively 
safe from injury. They need to be protected with salt hay 
or straw during the mid-winter months, beginning in Decem- 
ber, and allowing the protection to remain on the plants until 
March. In spring the covering is removed, the soil stirred 
with a hoe, and the lettuce plants made ready for heading, 
an end which they accomplish in April or early May. 
The ridge system has been and still is extensively fol- 
lowed by Philadelphia market gardeners, though the tend- 
eucy is toward the quicker results secured by under-glass 
methods. * The object of the ridge is to get good drainage 
and a kindly exposure to the sun’s rays, and these ends may 
be secured in almost any garden without much trouble or 
expense. 
The open-air seed bed of the autumn, in which the seed 
was dropped September 15, will usually carry its plants 
unharmed through the winter, if protected with straw or 
litter. The young plants from such a bed can be used for 
mid-winter forcing or for spring planting if desired. The 
advantage of the ridges, with their autumn-set plants, is 
merely in the fact that they save time. The earliest warm 
days start the plants to growing. 
CoLD FRAME CULTURE. The next simplest way to 
grow lettuce is in cold frames or ‘‘ boxes.’’ There is no arti- 
ficial heat of any kind ; no bottom heat furnished by manure. 
The glass protects the plants against wind and snow, and 
also fosters growth to some extent even in winter time. But 
during the months of December, January and February the 
lettuce plants do little more than hold their own. Vet all 
the time (except during excessive cold) they are adding 
strength to their roots; and this is not strange when we 
observe the persistence with which chickweed and other 
hardy plants grow in the cold frames during the winter 
months, and the apparent ease with which violets come into 
