Unhulled sweet-clover seed is sown principally in Kentucky, Alabama,
and Mississippi. On the limestone soils of regions, which appear to be
naturally adapted to sweet clover, very good results are obtained by
using unhulled seed. It is not because southern-grown unhulled seed
germinates better than northern-grown unhulled seed that better stands
are obtained in the South from it, but it is mainly because southern
farmers better understand the somewhat exacting conditions necessary
for obtaining a stand with this kind of seed. Unhulled sweet clover
contains a large percentage of hard seeds which will not germinate
until they have been in the soil for some time and have been subjected
to varying temperatures.
Seeding experiments have been conducted at Arlington, Va., where
unhulled seed which contained 90 per cent of hard seed was sown during
each month of the winter. Good stands were obtained on those plats
seeded at the rate of 24 pounds (3 pecks) of seed to the acre during
December and January, and fair stands on the plats seeded at this rate
in February. Later seedings failed to produce a stand.
A large percentage of the unhulled seed sown in the South is seeded
during January and the first part of February. Good stands are seldom
obtained from unhulled seed south of the latitude of Washington, D. C.,
when the seed is sown later than the middle of February.
The use of unhulled seed has usually been attended with failure in
the northern portion of the United States, although occasionally good
stands have been obtained the following spring from late fall seeding.
This failure is in part due to the fact that the seed has been sown
in the spring and at a tine when only seed germinating well should
be used. When unhulled seed is to be sown north of the latitude of
Washington, D. C., it should be sown not later than February 15, and
preferably earlier. Observations show that fairly good stands may be
obtained by seeding during the winter, but care should be taken not to
sow seed earlier than necessary on land which is subject to washing.
Farmers should have no trouble in purchasing hulled seed, and therefore
it is recommended that only hulled seed which germinates well be sown.