Hardy

The seed should be sown thinly in the open bordersduring March, April, or May in fine soil, covering slightly with
well-prepared mould--very small seeds require merely a dusting over
them. When the plants are large enough to handle, thin them out
boldly, to allow them to develop their true character. By this means
strong and sturdy plants are produced and their flowering properties
are enhanced. Many of the hardy annuals may be sown in August and
September for spring flowering, and require little or no protection
from frost.
Half-Hardy.--These are best sown in boxes 2 or 3 in. deep during
February and March, and placed on a slight hotbed, or in a greenhouse
at a temperature of about 60 degrees. The box should be nearly
filled with equal parts of good garden soil and coarse silver sand,
thoroughly mixed, and have holes at the bottom for drainage. Scatter
the seeds thinly and evenly over the soil and cover very lightly. Very
small seeds, such as lobelia and musk, should not be covered by earth,
but a sheet of glass over the box is beneficial, as it keeps the
moisture from evaporating too quickly. Should watering become
necessary, care must be taken that the seeds are not washed out. As
soon as the young plants appear, remove the glass and place them near
the light, where gentle ventilation can be given them to prevent long
and straggly growth. Harden off gradually, but do not plant out until
the weather is favourable. Seed may also be sown in a cold frame in
April, or in the open border during May; or the plants may be raised
in the windows of the sitting-room.