GROWING EARLY VEGETABLE PLANTS UNDER GLASS I53 
bility, and the flats are not uniform in size. Because of 
varying dimensions they cannot be placed in the frames 
without loss of space. When this annual loss is taken 
into account, it makes a strong argument for a uniform 
size of flats. When new lumber is used, the flats should 
be made to fit in the frames or on the greenhouse bench 
without loss of space. Chestnut is a durable wood for 
this purpose. The sides and bottoms should be made of 
Fa-inch and the ends of 24 -inch pieces. When nailing on 
the bottom pieces, about inch cracks should be left 
between them, to provide good drainage. Two inches is 
ample depth for most purposes. A deeper flat requires 
more soil and makes handling heavier. If the flats are 
about 2j>2 x 16 x 22J/2 inches, outside dimensions, three 
of them will fit in a 6-foot frame without an appreciable 
loss of space. Flats of smaller size are convenient for the 
retail plant business. 
