How To: Clean Up Hydrangea

Today I did some spring cleaning in my yard. Specifically with the White Dome Hydrangea (Hydrangea arborescens 'White Dome'). Like many people we left the hydrangea up for winter interest and now it is time to get them cleaned up for another growing season. Here is what they looked like before I started:

First I'll dive right into pruning the hydrangea, then I'll talk about cleaning up the ground underneath them. Note: This pruning method can be used for any Arborescens-type hydrangea including Annabelle, Invincibelle Spirit, Incrediball, and Bella Anna. It's best to wait until they have put out some new growth; you need to know where the live wood is before you can know where to start cutting. First, locate the set of leaves closest to the end of the stem. Then move down one set and make the cut just above those leaves.

Why? The second set of leaves is usually the most vigorous and the wood below it is the most healthy. Most often the second leaf set is larger than the first. It might feel like you're taking off too much of the plant. Don't worry - Hydrangea arborescens are vigorous growers, and not only grow back on old wood but send up new canes as well so it will have no problems filling out.

While cutting back the canes, keep an eye out for damaged or bent canes. Depending on the vigor of the leaves, cut these canes above the first or second leaf set below the damage. In the case shown below, I actually chose the third leaf set; the first set was on damaged wood and the second leaf set was weak.

It may be necessary to cut back all the way to the base of the plant. I noticed that some of the shrubs had canes growing along the ground. I cut these off all the way to the base, even if there were lots of nice leaves; having the canes in full contact with the mulch and soil is an invitation to rot and disease.

Sometimes the damage isn't as obvious as a cane that is bent or broken. If a cane twists easily to one side or flattens when you pinch it, it is a sign of an almost-dead cane and should be cut off. Here is what the inside of a healthy cane looks like:

Bright white pith with a healthy green ring.

And unhealthy canes:

Discolored, corky pith with gray ring.

Yellowing pith and slimy, mashy green ring.

Also, remove any spindly or thin canes. These canes don't have enough vigor to amount to much, and removing them will keep the plant's energy focused on the larger healthy canes, and prevent the center of the plant from becoming over-crowded.

~~~~~~~

Now, on to cleaning up under the hydrangea. Like I said earlier, we left the hydrangea up all winter. The downside of this is that the shrubs became leaf-catchers. The result is that there was a thick mat of leaves underneath the entire planting of hydrangea. So I started raking, and after the first few passes it was clear I started none too soon. First, I was amazed at how many leaves there were - 5 inches / 12.7 cm of wet leaves, courtesy of our Silver Maple (Acer saccharinum). Second, the debris at the bottom and the mulch underneath was rotting. Not decomposing into lovely soil - rotting into a soppy, fuzzy mess.

Waiting any longer to clean this up would have caused the bases of the hydrangea to rot. I was planning to topdress the area with some new mulch, but I'm going to hold off on that until the ground dries out.

So, how do you go about cleaning under hydrangea? I started out using my standard size garden rake, but it could only get so close to the plants before it started hooking the canes. So I switched to my mini-rake (every gardener needs one of these!) which easily reached into the narrow areas between the plants. But remember what I said about the leaf-catchers? The base of each hydrangea was stuffed with leaves. No rake would get them out, and certainly not a leaf blower. So I knelt down and pulled the leaves out by hand. (Gloves were a definite necessity - slimy leaves and soggy, fuzzy crabapples would not have been pleasant without them.)

I actually alternated between tasks: cut back some canes so I could get the rakes closer to the plant, rake a bit, trim some more, rake, remove leaves by hand, rake, move to another plant, repeat. It took about an hour to clean up five plants. Here is a reminder of what the area looked like before:

And here is the result - 

And the leaves? Remember, they were wet so this is not a fluffy leaf pile:

An hour or two of work, a job well done, and the White Dome Hydrangea are all set to go for summer!