Dahlias (Dahlia variabilis), native to Mexico, Central America and Colombia, are easy to grow perennials that present large, brilliant flowers in all colours of the rainbow. You can choose from 36 species and literally thousands of cultivated varieties of dahlias. Dahlias are grown from fleshy tubers planted in the spring. Soaking the tubers prior to planting encourages vigorous new growth. Dahlias provide a riot of colour in the garden all summer long. Dahlias will not survive a hard freeze and must be dug up in the fall. The tubers are stored for replanting.
Select firm, fleshy tubers for planting. Dahlia tubers may be purchased online or from home and garden supply centres. Dahlias are available as dwarf plants with button-sized flowers up to exhibition quality. Some dahlia tubers produce plants that can grow in excess of 5 feet tall and display flowers the size of dinner plates. Dahlias prefer an open, sunny location. Choose plants of a size appropriate for your garden space.
Examine tubers and select only those that are free of rot, mildew or mould. Firm, fleshy and healthy tubers will produce the best results. Dahlias prefer a neutral to high acidic soil. Avoid planting under trees or shrubs. Dahlias require nutrient-rich soil with fast drainage. If the tubers are constantly wet, or planted in soggy ground, root rot is encouraged.
Place the tubers in a tub or bucket. Cover with lukewarm water and let stand for two to four hours. Drain the liquid and your tubers are ready for planting. Dahlias do best in soil that is 50 per cent garden soil and 50 per cent organic matter. Add organic compost or well-aged herbivore manure -- sheep, cow, horse, llama, mule, goat -- to the soil and cultivate to a depth of 12 inches prior to planting dahlia tubers.
Plant tubers 10 to 12 inches deep spaced 12 inches apart. After planting, soak the area well, using a garden hose or sprinkler. Water should permeate to the tuber. Dahlias require plenty of moisture. Provide at least an inch of water per week. Never allow the soil to completely dry out.