Continue to fill in the hole as the plant grows. Place a stake 6 inches away from the root of the tall growing varieties at planting time. This is important because the central stem of the plant will need to be supported as it grows. When the plant is about a foot tall, tie it loosely to the stake. Continue tying the stem to the stake as the plant grows to insure an upright plant with straight branches.
Dahlias respond to deep and frequent waterings.
In hot, dry weather watering should be done at three-day intervals during the blooming season. Because dahlias are heavy feeders, they will respond to one or two sidedress fertilizer applications during the growing season. The first application should be made shortly after the sprouts emerge and the second in late July. Work it into the soil and water in well. Avoid getting fertilizer on the foliage.