When to plant Woodland sage 'Ostfriesland'?

Salvia nemorosa 'Ostfriesland' thrives in full sun but tolerates partial shade, though flowering may be less prolific in shadier spots. Choose a site with good drainage; this salvia is unfussy about soil type and grows happily in loam, sandy soil, or even chalky ground. Avoid heavy clay that stays waterlogged, as this can lead to root rot. Plant in March, April, or May for spring planting, or in September and October for autumn planting. Autumn planting allows roots to establish over winter, but spring planting works well if you keep new plants watered during dry spells. Before planting, dig over the soil and remove weeds. If your soil is heavy, work in some grit or coarse sand to improve drainage. There's no need to add rich compost or manure—'Ostfriesland' actually prefers lean to moderately fertile soil, which encourages sturdier growth and better flowering. Space plants 35 cm apart to allow for their mature spread of 30–45 cm. Dig a hole slightly larger than the root ball, place the plant so the crown sits at soil level, and firm in gently. Water thoroughly after planting to settle the soil around the roots, even if the ground is already moist. In spring plantings, water regularly for the first few weeks until the plant is established. Autumn-planted salvias need less attention but should be watered in if conditions are dry. A light mulch of gravel or grit around the base helps suppress weeds and keeps the crown well-drained, which is especially useful over winter.