depth at which the seed is sown. Seeds require light, heat, air, and
moisture for their germination. The ground should be light, and in
such a condition that the young roots can easily penetrate it, and in
all cases should be freshly dug so as to communicate air and moisture:
it should be neither too wet nor too dry. The most favourable time for
seed-sowing is just before a gentle rain. If sown too early on cold,
wet ground, the seed is apt to rot; when sown too shallow in a dry
time, there may not be sufficient moisture to cause it to sprout. The
seed should be sown evenly. The size of a seed is a nearly safe guide
as to the depth at which it should be sown. For instance, Beans and
Peas of all kinds should be sown about a couple of inches deep, while
very small flower-seeds merely require to be just covered. As to the
time for sowing, see "Annuals," "Biennials," and "Perennials."
Seeds, the Protection of.--In order to protect seeds against birds,
insects, and rodents, soak them in water containing 20 or 25 per cent,
of mineral oil. Vegetable seeds, such as Haricot Beans and Peas,
should be soaked for twelve hours, and the pips of Apples and Pears
for double that time. For soaking the finer seeds, bitter liquids,
such as that of Quassia and Gentian, should be used.
Sempervivum (Houseleek).--The hardy kinds are well known, and may
often be seen growing on the roofs of cottages and on walls. They make
good rock-work plants, and are easily increased by off-sets. The more
tender kinds are suitable for the greenhouse. These should be planted
in sandy loam and old brick rubbish. They require but very little
water; more may be given when they are in flower. Cuttings, after
being laid aside for a day or two to dry, will soon make root. Height,
6 in.
Senecio Pulcher (Noble Crimson Groundsel).--A warm position and a
deep, rich, well-drained soil are needed for this flower. It may be
propagated by cutting the roots into pieces 5 or 6 in. long, and
dibbling them into light soil. It is also increased by the rootlets,
which send up small growths in spring. Protect from damp and frost,
and keep a sharp look-out for slugs. The flowers are produced in
autumn. Height, 3 ft.
Senna, Bladder.--See "Colutea."
Sensitive Plant.--See "Mimosa."
Shallots.--Plant the bulbs in November, or in February or March, in
rows 9 in. apart, and the bulbs 6 in. one from the other. In July,
when the tops are dying down, lift the bulbs, lay them in the sunshine
to dry, then store them in a cool place.
Shamrock.--See "Trifolium Repens."
Sheep Scabious.--See "Jasione."
Shortia Galacifolia.--A hardy, creeping Alpine evergreen, having oval
leaves, slightly notched at the margins, which turn to a brilliant