I'm not really into dahlias. I admire the flowers, but I seem to get indifferent results in growing them. I've learned that there is nothing to be gained in our climate by planting them early: they make great growth initially, but when the summer weather arrives they go into a slump. They can be revived by cutting them back severely (at the height of summer, not exactly when one wants to do that sort of thing), watering them generously and feeding them. With luck, they bounce back for an encore during the autumn.
A simpler approach is to wait until early summer to plant them. This year I waited until the last week of June to plant my dahlias, and the result has been steady growth which is now blooming freely.
The dahlias you see above are representatives of a new group raised in New Zealand by Dr. Keith Hammett and called the Mystic series. I bought my plants last year and grew them that first year in pots. This year they are in the ground and are better for it. These Mystic dahlias are characterized by finely divided very dark foliage. This dark foliage makes a nice contrast to the vivid flowers. They look a lot like some of the Mexican wild dahlias.
The one shown above is 'Mystic Desire'.