The best way to have short stems and upright blooms is to prune in late winter or very early spring by cutting the branches back so that there is just two buds on each branch. Remove any weak or small branches by cutting them at their source. The less branches you have the bigger the flowers. You can harvest the blooms now by cutting them back with long stems of short stems keeping in mind that you will still need to prune the shrub in late winter in order to avoid the floppy shrub look. A soaker hose is a better way to water to avoid wet petals which tend to weigh down the plant. You can also try to train your hydrangeas to thrive on rainfall alone. This will create a smaller more compact shrub. Do not overfertilize or you will get long and lanky branches. I use two tablespoons of Osmocote Plus around each plant in the spring once I see signs of new growth. Your blooms are gorgeous and a gift to the neighborhood. Keep growing, Marianne Binetti