Dahlias prefer full sun, but will be okay in partial shade.

In fact, plants grown for show blooms are often shaded by large golf umbrellas or shade cloth to encourage longer stems, to avoid washing out vivid colorations and to protect the blooms from water spots. But remember that a typical four foot dahlia can get to 6-8 feet by reaching for the light.

If you are a new grower planting dahlias in any type of shade, be sure to water the plants more (tree canopy can act as an umbrella while roots wick moisture away) and stake each plant very well.

Thanks - I've tried growing dahlias twice before in pots (once from a tuber that grew but never flowered, and once from an already blooming plant from a garden center); neither of them really thrived, so I'd like to try putting them straight in the ground to see if they do better. Would you recommend starting from a tuber, or an already established plant?

If you are just beginning now you might want to buy an established plant, since tubers take a long time to produce flowers. You can try it out this year, and save the tuber to plant next year!

Do you have luck keeping tubers for 18 months out of the soil, Jennifer? How did you store them during the summer? I've accidently left extras in a shoe box with no storage medium, but the tubers were pretty shriveled with not much life.

On the East coast, we are just planting out now. You'd be amazed how quickly a tuber sprout catches up with a more mature plant once the soil is warm and ready to help grow.

I don't keep them out for that long. I dig them in November and plant them in May, so I've never tried to store them longer.