When more than one stalk comes up in the spring, cut off all but one nice strong one. Do you dig & divide? When dahlias are left in the ground from year to year you usually get many stalks & not much bloom-- when they are divided & one tuber is planted they are much more apt to get one nice strong stalk that you can stop & then it will branch out & give you more blooms.

I always dig and divide in the spring and several could have been clumps with multiple shoots. However a number were from cuttings. The leader stalk kind of withered and was later replaced with a number of stalks that ran horizontal for 1-1/2 feet then turned up. I tie then up to the stake but it is difficult with the right angle curve in each stalk.