How to Fertilize tree dahlia?
High-potash dahlia feed every two weeks from growth to flowering

tree dahlia · Dahlia excelsa
Also known as: imperial dahlia; tree dahlia
Grow in fertile, humus-rich, moist but well-drained soil, in full sun. Pinch out growing tips to encourage bushy plants and stake taller dahlias, see staking: perennials. Water freely in dry periods. Lift and store tubers in autumn to replant or use as a source of cuttings in spring. See dahlia cultivation
High-potash dahlia feed every two weeks from growth to flowering