Dahlia in May: monthly care

Dahlias thrive in full sun and need at least six hours of direct sunlight daily to produce their best blooms. Choose a sheltered spot protected from strong winds, as the tall stems can be brittle. They prefer well-drained loam or sandy soil enriched with plenty of organic matter. Before planting, dig over the soil to a spade's depth and work in a generous amount of well-rotted compost or manure to improve both drainage and fertility. Plant dahlia tubers from March to May once the risk of hard frost has passed, typically late April or early May in most of temperate Europe. You can also plant in September or October in milder areas, though spring planting is more reliable. Dig a hole about 12–15 cm deep and place the tuber horizontally with any visible growing points or "eyes" facing upwards. Space tubers 60 cm apart to allow for their mature spread and good air circulation. For taller varieties over 90 cm, insert a sturdy stake at planting time to avoid damaging the tuber later. Cover the tuber with about 5 cm of soil initially, then fill in the rest as shoots emerge. Water sparingly at first—overwatering dormant tubers can cause rot. Once shoots appear and growth is underway, water more generously. Apply a 5 cm layer of mulch around the base to retain moisture and suppress weeds, but keep it clear of the emerging stems. In colder zones, consider starting tubers indoors in pots during March and transplanting outside in May after hardening off.