A perennial flower that can measure from 3 to 16 inches in diameter, the dahlia flower blooms from midsummer to the first frost in every true colour except for green, brown and true blue. The dahlia plant is native to Mexico and can be frost sensitive, so planting dahlias when the weather is still cool and possibly before the last frost can pose some difficulties. Yet with a few basics for planting the dahlia tubers outside in April, these colourful flowers will emerge in various shapes and colours.
Grow dahlia tubers in an area that receives at least six hours of full sunlight each day. Prepare the planting area by loosening the soil at the end of March. Break up large clods of dirt and remove any large rocks.
Amend the soil with a low nitrogen fertiliser, such as 5-10-10, and work in well. The fertiliser should be a slow release formula so it continually supplies nutrients to the tubers once planted.
Dig a hole for each tuber that is long enough to lay the tuber on its side and deep enough so the top of the tuber is 3 inches below the ground surface. Space the holes about 2 feet apart.
Insert a 5-foot wooden stake in the ground next to each hole. Placing the stakes in the ground before planting ensures the tubers will not be damaged.
Place one dahlia tuber horizontally in each hole. Cover with soil, lightly firming over.
Water the tubers well after planting. Use a soaker hose and water three to four times per week just to keep the soil moist. Once the plants reach about 1 foot high, provide only about 1 inch of water per week.
Cover the newly planted tubers with 3 to 4 inches of mulch such as pine straw, shredded bark or compost. This helps to protect the tubers from possible frosty conditions and cool temperatures.
Do not use fishing line or wire to tie the dahlia to a stake.