A DASH of Gardening: Pruning – Hydrangeas

This is a high-level overview of some pruning best practices that can be applied to many garden and landscape plants, but with a focus on pruning hydrangeas. 

Winter Pruning – Hydrangeas

Now that we have survived the first major hard freeze of the year and it’s finally caused all my plants to drop their leaves (and I’m finally feeling a little less achy these days), I’m heading outside during these few bright winter days to continue working on the pruning and garden cleanup that I started in fall.  My focus between now and spring is to prune, prune, and prune my bushes and trees.

Since I became caretaker of this very old garden, I have been slowly working on cleaning up and rehabilitating it as best is possible.  The biggest issue to tackle being the overgrown and mature fruit and landscape trees that are starting to show their age.  At my previous house, I had run into many of the same issues, but at a much smaller scale.  I eventually hired an arborist and tree pruning service to come out and remove two trees and limb-up several others; something I likely need to do at my current house but is not immediately in the budget.  For now, I’m just slowly working my way around the house and trying to get as much pruned as I can each season.

A Little Bit About Hydrangeas

One bush I am extremely familiar with from my previous house and now have five of here at my current house is the hydrangea.  Hydrangeas are a very common bush grown in many Pacific Northwest gardens because they love moist, shady environments like we have here.  They also thrive well and become the incredible, intense blue shade when planted in acidic soils, like that created by decomposing pine needles and other plant material, another common feature of gardens in the great PNW.

Because you can get hydrangeas in a number of colors by growing them in different soil conditions, they are a favorite in floral arrangements and decorating.  Their fluffy blooms are frequently used to help fill out bouquets and centerpieces and add a lovely softness to the overall floral design, (check out this cute arrangement I did a couple years ago for Valentine’s day).  This is one of the best cut-and-come-again type plants because as you cut the blooms for filling vases, the bush will usually put the energy into growing more flowers, which means you get these great cloud-like bunches of flowers all summer and fall until the first frost.

Types of Hydrangeas

There are several types of hydrangeas that might be growing in your landscape, all have very similar bloom structures, but different leaf and growing habits.  At most of my local big hardware stores, I will see the Bigleaf Hydrangea or Hydrangea Macrophylla in several different colors depending on the soil acidity that was maintained by the nursery in which it was grown.  These are a nice landscape bush with the typical big round balls of fluffy blooms.  They generally have bright green leaves but can also have variegated foliage.  They can be quite vigorous growers, as I have experienced, especially if kept in rich, well-drained and moist soil and protected from harsh afternoon sun.  I have had several grow to be nearly 6’ tall, though they can be grown to as large as 10’.  Many people prefer to keep them in the 3-4’ size and they can be pruned as such if done carefully.

I have also seen at some of the larger local nurseries, such as Kent East Hill Nursery or Flower World in Maltby, some Hydrandgea Paniculata ‘Grandiflora’ or a Peegee hydrangea.  These are frequently pruned to take on a more tree-like form, similar to a lilac.  You can do the same with a Bigleaf Hydrandgea, but I tend to think they do better as a bush.  The Peegee has these lovely, elongated clusters of blooms that droop off them in the summer.  They typically start white and turn pink, I have not seen any that have been made blue or purple through soil treatment, but perhaps someone out there is doing that.   With a similar bloom form, but much different leaf shape, you can also find at some nurseries the Oakleaf Hydrangea or Hydrangea quercifolia.  Just like their name suggests, they have fun, oakleaf shaped leaves, as well as pretty, reddish bark that can be appealing in the winter months.

The last growing form of the hydrangea is a climbing type.  These are a wonderful vine like version of the hydrangea that can stretch as long as 40’ or more if kept in good conditions and well maintained.  These have lovely white flowers and dark green leaves.  The bare vines remind me a bit of very mature grape vines.  There is one of these growing on the south side of my house and has now merged with the old split-rail fence it was grown against.  I’m currently considering relocating this somehow since my neighbor is planning on partially replacing the fence and I’m concerned about its longevity in its current location.  Another dilemma for another day to be solved.

How I Prune Hydrangeas

I have three hydrangeas, all a bigleaf variety, in the garden bed at the east side of my house.  Two of which were planted by the original owner, and one I added last spring.  The older hydrangeas I cut back severely my first winter in the house as they had been poorly pruned or not at all over the years and were an irregular blob of greenery without any blooms on them.  It was pretty sad since I knew that the severe hacking I was giving them that season was only going to prevent them from blooming again but would hopefully allow me to cut out some of the bad older growth this winter…which I did.

I’m going to start with the small one I planted this past spring.  Happily, it survived the very dry summer and autumn due to my consistent watering, and now is working on some new growth.  This is a perfect time to prune this because I can see easily what is dead versus not and where I am going to get growth versus likely not.  Once I prune, the plant will put energy into growing leaves and new shoots just at and below the point at which I cut.  This in turn will promote more bushiness in spring and help make the branches more robust and less leggy as it continues to grow.

My goal with this little guy, and the other two hydrangeas I was gifted by my boyfriend’s wonderful mother, is just to cut out the dead things and cut back the remaining branches by about half.  I’m also looking for any branches or shoots that are going to grow unproductively this next season, such as those that are going to rub or cross over other stronger branches.  This can create rub spots and cankers on the limbs that make it more susceptible to disease or rot.  You can see that once it’s cleaned up, it looks pretty sparse, but trust me that this is better for it to continue to develop into a stronger larger bush this next season.

The next hydrangea I tackle is the smaller of the two that were existing when I moved into this house.  This one did bloom last year, and had some pretty light blue clusters, but was still in recovery mode mostly from the intense haircut it got the past winter; I only got about four blooms.  The hydrangea is only going to create shoots that will grow blooms off of old or existing wood.  You will not get them off the new shoots coming in from the ground. 

So, keeping that in mind and with the same principles I had applied to the smallest bush, I pruned the hydrangea back.  This one had several older branches though that I really needed to get out because of how wonky they’d been growing for so long.  I decided to go ahead and take them out and risk that I would again not have a lot of blooms on this bush this year for the sake of the plant’s longer-term health and appearance.  It’s a nice size right now that I feel I’m intervening at a good time for it to mature into a nicely shaped and healthy specimen. 

Clearing out the middle of these bushes of dead leaves that have settled into their centers in also a good way to promote the health of the bush and mitigate risk of disease or mold growth.  After a much less intense haircut, I am left with a much sparser bush, but still with lots of good opportunities for new growth and maybe some blooms.

The last hydrangea I’m pruning in this post is the biggest and oldest of the three in this garden bed.  It was tucked back into the corner against the house and has been stretching itself out in order to get better access to light and nutrients since it was planted.  Hydrangeas can tolerate and do well in shade, but this one may eventually need to be migrated further from the house; we’ll see how it does this next season. 

Similar to the other older hydrangea, I had really intensely cut this one back last year, and again this year in order to remove the older, poorer growth.  This one did not bloom at all last year, but instead just grew a ton of new shoots, which was great, but needs to be reeled in again.  I’m hopeful that even though I’m doing another heavy pruning it will bloom and I can see what they look like, but right now I really just want this to get into better growing form.  Same principles of pruning as the others, but I’m taking out more of the growth in the middle of the bush and as many of the old and twisted branches as I can to promote the growth on the straighter newer shoots from last year.

Nice cuts!

When you prune most bushes or plants, you want to pay attention to where the plant is able to produce buds or new growth from and aim to cut immediately above that point at an angle, without damaging the growing node or bud.  Leaving too much wood or stem behind can create a point for disease to enter as that piece of wood beyond the growth point dies off.

If you are like me though and are sometimes a little less dexterous or very shakey, just try to get as close to the bud or growth point as possible and come back another day when you’re steadier and retrim as required.  Many plants are really forgiving and can survive some less-than-ideal pruning, such as the hydrangea, but as you are able, it’s best to go back and re-prune where there is extra dead wood to prevent disease or rot issues.  You may try doing a first round of pruning with some larger shears you can control better, then another day do some touch-up with a smaller set of sharp nippers.

Happy pruning!