Hydrangea paniculata 'Limelight' in July

PeeGee or panicled hydrangea (Hydrangea paniculata) and our native Smooth hydrangea (Hydrangea arborescens) are pruned now in late winter thru early spring. Why? – because these hydrangeas bloom on new or current season’s wood.

Over the years these two hydrangea species grow to enormous sizes. When they overwhelm their garden space, severely cut them back to within 6 -12  inches from the ground in late winter or early spring. Next, thin out the number of shoots (canes), leaving several of pencil size thickness.  In the spring each cane will grow out new shoots which bloom this summer.

Severe cutting back  is called renewal pruning. Timing will vary with the species of hydrangeas planted in your garden.  After pruning apply a slow release fertilizer especially formulated for flowering shrubs. Follow the package directions. Apply a good organic mulch to a 2 – 3 inch depth around each hydrangea to conserve  soil moisture this summer.

Oakleaf (H. quercifolia) and  bigleaf  (H. macrophylla) hydrangeas may also be pruned now, but flower numbers in spring and summer may be greatly reduced.