DESCRIPTION: This group consists of two-hundred trailing perennials and annuals and evergreen and deciduous shrubby plants. They are found throughout temperate and tropical countries. These plants usually have heart-shaped leaves and, in the summer, bear beautiful, funnel-shaped flowers. Convolvulus are commonly known as Bindweeds. Most of the perennial kinds spread rapidly and care must be taken that they don't crowd other plants. Some, such as C. arvensis (Lesser Bindweed), are troublesome weeds in the garden. Some of these plants are suitable for growing in rock gardens; some, in flower borders; and others, such as the tender kinds, in the greenhouse. One of the prettiest for the rock garden is C. althaeoides. This low growing, trailing plant produces rosy pink flowers in June and July. It shouldn't be placed near choice plants, however, because it may become too difficult to manage. C. cneorum (Silverbush) is a gorgeous, tender, evergreen, bushy plant that is suitable for the rock garden. It grows about 2 feet high and is covered with silvery, silky foliage. The pale pink and white, funnel-shaped blossoms are produced mainly in late spring, though they may grow sporadically for several months. C. mauritanicus is a tender, trailing plant with blue flowers. The annual variety, C. tricolor, is a very pretty plant suitable for the cool greenhouse. It blooms over a long period in late winter and spring if it had been raised from seed the previous September.
POTTING: The perennial varieties can grow in any regular, well-drained, garden soil.
C. mauritanicus and C. Cneorum need a gritty, very well-drained soil and a sunny position. They will be hardier and produce more flowers in that kind of soil.
Those grown in a greenhouse can have any good soil that it well drained. They should have a sunny spot and a night temperature of 45º to 50º F, with a few degrees rise in the day. Plants that have filled their pots up with roots should be given weekly applications of dilute liquid fertilizer. The plants will flower in pots that are 5 inches in diameter. C. Cneorum can be used as a greenhouse plant, though it still needs sandy, well-drained soil and full exposure to sunlight. This plant shouldn't be placed into a container that is too large compared to the size of the plant. In the summer, it may be set to its rim in a bed of sand or ashes outside. Throughout the summer, the tips of the shoots should be pinched to keep the plant bushy. When grown indoors this plant blooms over a long period in late winter and spring.
PROPAGATION: C. Cneorum and C. mauritanicus can be propagated by sowing seeds in boxes of soil in a frame, or by separating the plants into rooted pieces, in the spring. C. Cneorum also roots easily from cuttings inserted in sand in a greenhouse or cold frame, in the spring or fall. Seeds of C. tricolor may be sown to produce more plants. C. tricolor minor (dwarf variety) can be raised by seeds sown in a sunny, cool greenhouse or frame in March. Seeds may also be sown directly outdoors in late April.
VARIETIES - Perennials: C. arvensis (the Lesser Bindweed -pesky weed); C. althaeoides (great for rock garden).
Tender - can be grown in a greenhouse: C. mauritanicus; C. cneorum (Silverbush); C. tricolor & var. minor (dwarf annual).