Tips for Fall Clean Up and Pruning
On a beautiful fall day, garden clean up can feel so rewarding.... on a cold, rainy day, perhaps it's best to stay inside and just admire the fall colors. It's not a good idea to prune when it's wet, anyway, so you have a valid excuse!
Hydrangeas - so much mystery and confusion! Here are some explanations:
Big Leaf Hydrangeas - we grow only the varieties that are hardy here in zone 5, and these bloom primarily on current year's new growth. You may have one of the 'Endless Summer' types like 'BloomStruck', 'Blushing Bride', or 'Summer Crush' , or you may have one or more of the hundreds of other varieties! They bloom on new and old wood, but they mostly die back to the ground with our up and down winter weather so we rely on new growth for blooms.
But if we do have old branches surviving our winter, we want those blooms, too - so don't prune these until spring! Wait until you see green buds on the branches and/or at the very base of the plant. This might be late May depending on temperature. Prune dead branches back to the point of the new, green buds.
Smooth Hydrangeas - these are the 'Annabelles' of the world, or perhaps you have one of the new 'Mini Mauvettes'. These also bloom on new wood, and benefit from pruning because it strengthens the branches and encourages new branches, which results in more blooms! Pruning can be done in fall, but spring pruning is best. Wait for buds to start showing green, then prune back by about 1/3 of the height.
Panicle Hydrangeas - these are the woody. shrubby hydrangeas like 'Vanilla Strawberry', 'Diamond Rouge', 'Quick Fire', 'Limelight'', 'Little Lime', or 'Bobo', that do not need to be pruned at all if the height is good. Just remove the dead flowers either in fall or spring. If you have an extraordinarily tall variety, such as 'Limelight', prune back by as much as 1/2 of its height in the spring just before the leaves appear. Watch for those leaf buds to swell and start to turn green.
Choose your place to cut just above an outward facing bud to make sure your new branches grow the "right" way (up and out, not in, down, or crossing)
Climbing Hydrangea - these bloom on old wood, so if you prune in the fall or spring you will be removing flower buds. Best to prune right after flowering in the summer if corrective pruning is needed. Otherwise, don't prune except to remove old flower heads or dead branches.
Oakleaf Hydrangea - These are often used at the woodland edge, and can get quite large. They bloom on old wood (previous season's growth), so don't prune late fall or spring. If pruning is needed, prune no later that August after the blooms have appeared. If no pruning is needed, just remove the previous year's blossoms.
Most are best left standing for winter interest. Birds will perch on them and eat the seeds, beneficial insects might be making a winter home there, and most of the grasses stand up well to the winter winds and snow providing a beautiful background for winter. Calamagrostis "Karl Foerster' is one that I sometimes cut back in fall, but only because it emerges in spring so much earlier than the others and I am often busy in spring and forget to cut it back before the new growth starts.
Lavender, butterfly bush, beauty berry - leave them standing until spring. Some plants appreciate having extra branches to help them through the winter. If there is dieback, you can prune that out in spring after the new growth starts!