2 varieties of Dinnerplate dahlia Kelvin Floodlight and Lilac Time The dahlia tubers are planted in pots in March–April or in the ground in May–June. Plant them 30–75 cm apart depending on the variety. Because of their lush growth, dahlias consume a lot of water and nutrients. Dahlias should be watered and fertilised regularly Tall varieties should be supported as needed. Cut off the wilted flowers. As soon as night frosts have damaged the shoots, trim them at a height of 10 cm. The roots of the dahlia are kept in peat during the winter at a temperature of 3–10 degrees Celsius. A great cut flower.