Sphenogyne Speciosa.—­An elegant hardy annual.  Sow the seed early in spring on a gentle hotbed in loam and peat, harden off, and transplant at the end of May to a soil composed of loam and leaf-mould, if peat cannot be obtained.  The bloom is produced in July.  Height, 1 ft.

Spider Wort.—­See “Commelina” and “Tradescantia.”

Spigelia Marilandica.—­From August to October this hardy perennial produces tubular crimson and yellow flowers.  It finds a congenial home in damp peat, shaded from the sun, and may be propagated by cuttings in loam and peat under glass.  Height, 1 ft.

Spinach.—­For summer use sow the round-seeded kinds at intervals of two or three weeks from February to the end of July in rows 1 ft. apart, cover with the finest of soil, and thin out to a distance of 3 or 4 in.  In dry weather give a liberal supply of manure water.  Pull before it runs to seed.  For winter use sow the prickly-seeded variety in August and September, and thin the plants out 9 in. apart.  If the ground is hot and dry, the seed should be soaked for twenty-four hours before it is sown.  New Zealand Spinach may be sown in the open during May, choosing the warmest spot for its growth; but it is best to sow it in heat in March, keeping the soil fairly moist, and, after hardening it off, to plant it out in June, 3 ft. apart Sow Perpetual Spinach or Spinach Beet in March in drills 1 ft. apart.  Cut the leaves frequently, when a fresh crop will be produced.

Spiraeas.—­Placed in the open ground these make splendid plants, and are not particular as to soil, though a moist, rich one is preferable.  For forcing, plant the clumps in 6-in. pots, and keep them in a cool frame until they are well rooted.  They may then be removed indoors and forced rapidly, supplying them with an abundance of water.  Their elegant flower spikes are invaluable for bouquets and table decoration.  The shrubby kinds are increased by layers or cuttings of the young wood, the herbaceous varieties by division of the roots in autumn.  Spiraea Aruncus, if potted early in the autumn, is very valuable for winter decoration.  Spiraeas bloom at different periods, from May to August, and vary in height, 3 or 4 ft. being the general growth.

Spruce Firs.—­See “Abies.”

Stachys Coccinea.—­This scarlet hardy annual is fine for bees.  It may be grown in any soil from seed sown in March or April.  Height, 1 ft.

Stachys Lanata.—­A hardy perennial which will grow in any soil, and bears division.  It flowers in July.  Height, 2 ft.

Staphylea Colchica_(Mexican Bladder Nut)._—­This beautiful free-flowering shrub will grow in any garden soil, and produces bunches of fragrant, delicate white flowers in June.  It forces well, and may be made to flower at Easter by potting it in rich, light soil, placing it in a cold frame till the middle of January, keeping the roots moist, then bringing it into the warm house.  It may be propagated by suckers from the roots, by layers, or by cuttings taken in autumn.