Try Swan Island Dahlias in Oregon. They have always been helpful to me.

There is detailed info of about 300 varieties at: http://cubits.org/Dahlias/db/dahlia/browse.php

You can also check out the vendor list (some vendors have very detailed info about each variety they sell) at:

Www.dahliaaddict.com

Keep in mind that climate, fertility of soil and sun intensity can cause differences of growth in the same variety. One foot of difference is not really that much, and can vary year to year... 3 feet versus 6 feet really matters when planning a tiered garden.

Thanks guys for the quick responses. My main concern is taller plants in the rear of the bed. Also, do they need much fertilizer, and if so, when? I've got really good soil, have been adding organic matter for years, so I use very little.

Thanks again

I also like this database: http://davesgarden.com/guides/pf/?q=dahlias