Last year, my dahlias grew so tall that I had to stand on tip-toe to reach the blooms at the top of the plants. Varieties that were advertised as five footers stretched to seven feet or more. Staking quickly degenerated into an ugly wrestling match in which my poles, twine, and personal dignity suffered humiliating defeats. By the end of the summer, the plants were listing to the side like a row of inebriated red, orange, and burgundy bedecked party-goers.
So this year I wanted to make sure that I was careful to top the dahlias. Bloomin' mad dahlia aficionados do this in order to produce the largest flowers; I was topping in order to produce a smaller plant. The topped plant directs its energy into the lateral stems, ideally resulting in a fuller, more easily maintained plant. Here's all you do.
First, make sure the the plant has three or four pairs of true leaves. Take care not to include in your count the cotyledon leaves--the smaller leaves near the ground. (To keep the plant clean from foliage-bourne diseases, you can remove those cotyledon leaves anyway when the plant is about a foot high.)
Next, reach in between the pair of leaves and, using your fingernails, pinch out the stalk. Be careful not to crush, pinch, or damage any little leaves that are growing to either side of the stalk. Those guys are going to grow up to become laterals.
Cruel to be kind: it may hurt now to take away that delicious green growth but not as much as dahlia wrangling later. Next on the agenda: replacing the current light weight stakes with the heavy duty models. I'm betting on blooms by early July.