For summer blooming plants sow seed in the house, in March or April.
Cigar boxes are very suitable for seed sowing. Put in a layer of coarse
sand for drainage, then one of horse manure for bottom heat. Fill with
rich, mellow earth sifted and mixed with one-third silver sand, or
finely pulverized leaf mold. Have it moist but not drenched. With a
narrow strip of board, make tiny furrows about one and a half inches
apart, and in these carefully drop the seed one by one an inch distant.
Cover slightly, and press the soil firmly, then lay a piece of old soft
flannel folded once or twice, and wrung lightly out of warm water,
carefully over the soil, which will keep it damp. Cover with glass, and
keep in a warm place. In a few days see if the covering is dry, if so
damp it again, and watch for the seedlings. When they appear, remove the
flannel, but still keep on the glass, not, however, so close as to
exclude all air. Gradually inure them to the sunlight, and as soon as
they have made four or five leaves, it is best to transplant every other
one, so that they may have room to grow. Great care is needful with
tender seedlings to keep them from damping off. If too wet, they will do
this, or if kept too shady. Good judgment is essential for success. As
the weather becomes warm, expose them at first an hour or two, to the
outdoor air, and thus prepare them for early bedding out. Being hardy
plants, living out of doors during the winter, with slight protection at
the North, they will bear transplanting sooner than many other
seedlings. A rich moist soil, and somewhat cool and shaded situation,
are best adapted for their growth. For winter flowers, sow seed the last
of August, or first of September, in a frame or boxes kept in a shady
place.