Sow February to July in trays or pots, use good seed compost in a propagator or warm place to maintain an optimum temperature of 60-65F (15-18C). Sow in well drained compost, just covering the seed with compost. Germination takes between 14 - 30 days.
Transplant seedlings when large enough to handle. Harden off and plant out when all risk of frost has passed. Space the plants 30cm (12in) apart in full sun.
Hybrid cultivars can be propagated by rooting softwood cuttings in the spring or early summer before flowering.
Semi hard wood cuttings are taken from the current years growth from late summer to mid autumn the bottom of the cuttings is hard and soft on the top. With a sharp knife take a cutting of about 14cms, remove lowest leaves, if desired you can dip your cuttings into a rooting hormone before placing round the edge of a pot filled with a suitable compost, water well, they must remain moist till rooted, place under glass but in semi shade.
To divide Agastache, dig the entire clump. Pull the plant into smaller clumps, each with at least three or four shoots and a healthy root system. Discard old, woody sections and replant the divisions. Most perennials benefit from division once every two or three years.