210 FARM GRASSES OF THE UNITED STATES 
nate if covered to any considerable depth. An eighth 
of an inch is an ideal depth, and one-fourth inch as 
deep as is at all safe. The careful use of the roller 
will press all the seed into the soil, and at the same 
time it firms the surface soil in a very helpful way. 
On small plats a light mulch of rotten leaf mold or 
similar substance will protect from birds and prevent 
the drying of the surface soil. If it is necessary to 
water to promote germination this should be done 
with great care, imitating a gentle rain as much as 
possible. At the same time it is well to fully soak 
the ground, so that no more water may be neces- 
sary till the grass is well up and out of danger of 
injury. 
Grass-seeds may be sown at almost any time of the 
year. ‘The early spring and early fall months are de- 
cidedly preferable, however. Most of our lawn grasses 
—at least, those used in the Northern States—are 
adapted to cool climates, and make their best growth in 
cool weather. Spring sowing should be done as early as 
possible, so that the grass may become firmly established 
before hot weather setsin. Fall sowing should be done 
in the latter part of August or in September. Grasses 
started then will be well set before winter. Seeds sown 
late in October will generally not germinate that fall, 
but if conditions are favorable will remain in the ground 
over winter and start very early the following spring. 
Unless a quick cover crop is needed to prevent washing 
of the land or for the green appearance, no nurse crop 
should be used with grass-seed. Grasses seldom need 
any protection, and are often injured by the shading and 
smothering of the more vigorous nurse crop. 
