Soldanellas.—­These small herbaceous perennials should find a place in all Alpine collections.  They grow best in sandy peat, or in leaf-mould with a liberal addition of sand, and they require a moderate amount of moisture.  They may be increased by dividing the roots in April.  They flower from March to May.  Height, 4 in. or 5 in.

Solidago (Golden Rod).—­A useful hardy perennial for the back of borders.  Throughout late summer and autumn it produces masses of golden flowers.  It is not over-particular as to soil, and may be increased by dividing the root in the spring.  It increases very rapidly.  Height, 2 ft. to 6 ft.

Solomon’s Seal (Polygonatum Multiflorum).—­A graceful hardy plant bearing white pendulent flowers on long curving stems.  Plant freely in light, rich soil, in a shady position or under trees.  The plants should not be disturbed, even by digging among the roots.  Flowers in May.  Height, 2 ft.

Soot-Water.—­For room and window plants soot-water has this advantage over coarse animal manures, that while the latter are unhealthy and apt to taint the air, the former is purifying and has no unpleasant smell.  It is easily made by tying a little soot in a coarse canvas bag and immersing it in a pail of water.  It should be applied in a clear, thin state to plants in bud or in full growth during the summer months.

Sorrel.—­Sow in March or April in any garden soil, thin out to 1 ft. apart.  It is desirable to cut away the flower-stems and to divide the roots every two or three years.  The plants may be forced for winter use.

Southernwood (Artemisia Arborea).—­Any soil suits this odoriferous bush, and it is readily increased by cuttings or by division.

Sparaxis.—­Closely allied to the Ixias, equally beautiful and varied in colour, but rather dwarfer and compact in growth.  Invaluable for pot-culture.  For outdoor cultivation plant them early in September, 5 or 6 in. deep, on a sheltered border, in rich, well-drained, loamy soil.  Protect from frost and wet in the winter, but keep the roots moist while they are growing.  For indoor cultivation plant four to six bulbs in a 5-in. pot, plunge in ashes in a cold frame, withholding water till the plants appear.  When making full growth remove them to a sunny window or conservatory, and water them carefully.  They will bloom in March or April.  Height, 3 ft.

Sparmannia Africana.—­An exceedingly handsome and attractive greenhouse evergreen shrub, thriving best in loam and peat.  Cuttings may be struck in sand under glass.  May is its flowering season.  Height, 10 ft.

Spartium Junceum(Yellow Broom).—­A hardy evergreen shrub which will grow in any soil, and is propagated by seeds.  It flowers in August.  Height, 6 ft.

Specularia Speculum.—­See “Venus’s Looking-Glass.”

Spergula Pilfera.—­May be grown in any moist situation in sandy soil. 
It is of little value.