Dahlia 'Annika': A glorious dark-leaved dahlia, which will produce a prolific and very showy display of vibrant flowers from midsummer. The contrast between the magenta-pink blooms and purple flushed foliage is brilliant and is particularly useful for adding a colourful twist to the planting scheme. Grows to 45cm.
There’s no need to water the soil until the dahlia plants appear; in fact, overwatering can cause tubers to rot. After dahlias are established, provide a deep watering 2 to 3 times a week for at least 30 minutes with a sprinkler (and more in dry, hot climates).Like many large-flower hybrid plants, the big dahlias may need extra attention before or after rain, when open blooms tend to fill up with water or take a beating from the wind.
To flower well, dahlias need full sun, preferably at least 8 hours. In hotter climates, (Zones 8 and up) they will do better with some afternoon shade.
A mid-season application of an organic flower food will give them a boost. Whatever fertilizer you choose, look for one with a low nitrogen ratio. Don't fertilize after August. You are going to be digging and storing the tubers soon and you want them ready to go dormant.
Dahlias like a rich, well-draining soil with plenty of organic matter and a fairly neutral soil pH around 6.5
A lot of growing information says to pinch the growing tip, to encourage multiple stems. Hans says that is not necessary and will actually reduce the size of the mature plant. Instead, he recommends removing only the first flower bud. That will be enough for the plant to branch out.
Dahlia foliage dies back with the first light frost in fall. In colder regions, the tubers should be dug up before the first hard freeze and stored indoors.
If you are planting your tubers in containers, mix in 1/3 garden soil, for better moisture retention. Potting soil dries out quickly and the tubers need to stay moist until they have sufficient roots.