They were first promoted as food crops for their edible tubers, but didn't please the European palates and were almost forgotten. With a little royal help from Empress Josephine at her gardens at Malmaison they started gaining popularity as ornamentals. The first species were tall and single-flowered, but in 1800's new double forms were bred in varied colors, especially in Germany. They were grown as perennials and propagated by division of the fleshy tubers. The compact bedding dahlias grown from seed, as we know them today, were first produced in this century.
Dahlias are easy to grow from seed.
They are short-day plants and start flowering in the latter part of summer. There is much variation in plants produced from seed, but with their bushy, green foliage and brilliant colors they are unequalled when massed in sunny borders. In my garden they are favorite flowers of butterflies, attracting hundreds of them on sunny late summer days. Seeds and young plants are available from most seed companies and nurseries. The tubers of the best plants can be lifted in the autumn, left to dry for a few days and stored frost free.