This genus consists of about 250 species of evergreen or deciduous perennials. They produce leaves which are opposite, while the flowers bloom in compact heads of spikes or panicles, which are tubular with 5 terminal unequal lobes. They are frost hardy to frost tender, min 15C and will prefer semi-shade. You should grow in fertile, well drained soil. Propagate by seed, basal stem cuttings or division in the spring.
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