Do It Now


I usually write about hydrangeas in the late summer, when they are gracing most every garden in my zone with their armloads of marvelously frothy flowers. Ha. Hopefully that written description sounds just as extravagant as they appear in full bloom. This shrub, and all of its many iterations and cultivars, energizes and endows our late season landscape with an unparalleled and succinct representation of summer. Who doesn’t swoon over hydrangeas in bloom? I do. Each properly placed and well grown shrub is covered in flowers for weeks at summer’s end. It is indeed the super nova stage of the summer landscape. A brass band playing loudly in perfectly brassy unison, if you will. Hydrangeas representing in all their glory define what it means to be robust. They are so willing, and eminently worth cultivating. They give so much more than they need or demand. They are not wall flowers, or delicate ephemerals, or  gracefully weedy perennials-nor are they on that tough to grow list. They are like a freight train pulling in to the station with steam billowing up from the tracks and a horn blaring. Are you ready? If the leaf buds have broken dormancy and are swollen all along the stems of the shrubs  – and if those swelling buds are greening up  – it is time to prune.

Let me get what not to do out of the way first. My opinion on the matter is all I have to offer. Do not prune in the fall. Pruning is a call to grow.  Encouraging a shrub that is facing the winter to get up and grow is just not a good idea. Your best move is to encourage the long sleep. Movement towards winter dormancy in woody plants starts in my zone in August.  Once the leaves turn color, mature, and drop, leave all of the rest of the shrub intact. The most important thing to do to hydrangeas in the fall is nothing. Do not cut the flower heads off.  They look lovely with snow on them, and they wave in the winter winds. That cinnamon brown color is beautiful with evergreens. If you must remove the flower heads, OK, but do not cut these shrubs down to the ground in the fall.  That will force them to sprout from below ground in the spring. Be merciful. Leave at least 3 or 4 buds above ground when you prune-in the spring. If you are growing big leaf hydrangeas-as in hydrangeas that bloom on the previous year’s wood/growth, do not prune in the fall or the spring. Prune them promptly and only after they finish blooming. If you don’t know which type of hydrangeas you are growing, find out before you prune.

Hydrangeas do not respond very well to a formal shearing. Few plants do. Shearing hydrangeas  encourages multiple breaks below the cut, which result in a dense thicket of stems and leaves at the top. The bottom half of the shrub gets shaded.  I am amazed at how many hydrangeas I see pruned like this, but it is not good for the health of the plant, or the flowers.  I give my hydrangeas a shag haircut, keeping the stems at the top shorter and the stems nearer the bottom longer. The idea is to provide a sunny and airy space for each branch to live free. You can see this arrangement in the location of the flower heads in the photo above. Each branch has its own address.

What might not be so obvious is that these last 2 pictures show two different types in hydrangeas.  On the far left and far right of a center block of Limelight hydrangeas, as in Hydrangea paniculata “Limelight”, are rows of Incrediballs – Hydrangea arborescens “Incrediball.   They add flowers at a lower level, and they bloom earlier than Limelight. Their upright plant habit and carriage is vastly superior to their predecessor, the storied “Annabelle”.  You can see the Incrediball flowers are fairly round, and the Limelights are broadly cone shaped.  A certain amount of legginess is inevitable with Limelight. That mess of twigs is what you get over the winter with them. The Incrediballs help cover up those bare legs. These cultivars have different parentage, but they are pruned the same way.  They bloom on new growth. On what will be the current years growth.

So if it’s not appropriate to prune hydrangeas by shearing, what is the purpose of setting stakes and string? My yard, where these photographs were taken, slopes dramatically from one end to the other. The blocks of hydrangeas are a good distance apart. I would want those blocks to loosely resemble one another. The only way to tell if they approximately occupy the same spot in the landscape composition on both the north and south is to set up a level line. It’s easy to do with a bamboo stake or metal fence post, and a ball of spring. A tiny level can be clipped on to the string.

Pruning by eye can be incredibly inaccurate. I see a lot of that too. Pruning that matches uneven terrain, or follows a sloping driveway. Or pruning just to prune, with no thought to the horizon. I see that too. Sometimes it is hard to believe a level attached to a string line is accurate, but it is. I would never trust my eye to see a level line for pruning. It is terrible to wade through a big pruning project only to discover your vision for them is lopsided. And what is required to set it to right is not possible until the mistake grows out. I shudder to think of that. Happily most plants are very tolerant of off the cuff pruning. The recovery just takes time.

My level line set up is an approximation of the horizon. In the ballpark, as it were, or within shouting distance. It is not exact. It does not represent or enforce a rule. Nor does it rule the pruning process. It provides orientation. As in up and down, and left and right. It provides a framework from which to work. Taking the time to set up 2 poles and a level line is a way to walk away from the the noise of the day, and study on this first foray into the new garden season. It is a way to get ready for the job at hand. But in spite of all this, should you decide to prune your hydrangeas from the hip, Mother Nature will treat you just the same as any other gardener. Indifferently. But indeed you will notice the difference.

The pruning of my hydrangeas is underway.

A Pruning Strategy

The best time to prune deciduous shrubs is whenever you have the time available to prune. But no doubt some pruning dates are better than others. Late March is the perfect time time in my zone, provided the ground is dry enough be walked on. The bare branches make it easy to spot what is dead or weak. Or which cuts would result in a better looking or more graceful shape. In general, the shag haircut theory of pruning promotes good shrub health. Big at the bottom, and narrower at the top. Pruning such that no two branches are the same height or forced to  occupy the same space helps to insure that every bud ready to leaf out will have its own light and air space. A place to grow without interference is an ideal place for a branch to be. I like to leave the branches near the ground long, and the branches on the top shorter. Visualizing what has to be cut back on the top so the lower branches get the light they need will result in a shrub that is green and growing from top to bottom. If you think the Limelight hydrangeas above do not look like I took my own advice, you are right.

There is a story behind these leggy Limelights.  Planted as a 5 plant by 5 plant block of 25 some 12 years ago, they had overgrown their space. The lesson here? A shrub that will grow 6 feet tall by 6 feet wide probably will top out at 8′ by 8′ left to its own devices. Keeping a plant smaller than its genetically determined size is, over time, a losing battle. My 25 plants had become a single organism. Removing any of them from the mix would expose a not so lovely look at a dark and bare interior. It was time to take out the outer front and side rows. Once I reduced the size of the block to a four plant by 4 plant block, I could see what I had left over was a mass of hydrangeas on 3′ tall bare stalks. As in, a block of multi-trunked hydrangeas on standard.

Of course these hydrangeas had gotten leggy in the interior. I am sure no light reached the ground during the summer. The outside rows has been pruned to facilitate growth from top to bottom. The interior shrubs has been pruned to encourage growth on the tops. All very predictable, this. Last spring I planted Little Lime hydrangeas in from of those Limelight legs, thinking this shorter version would create a coverup.

That strategy left more that a little to be desired. Little Lime is by no means a smaller growing version of Limelight. The flowers are a different shape and color. I was not crazy about the two plants side by side. Hydrangea Bobo might have been a better choice. That said, I knew my only real option with the limelights was to take a renovation strategy. Hard pruning old hydrangeas hard is only shocking if you do not take into account how fast and much they grow between April and the late July bloom time. A single branch may grow 3 or 4 feet in one season.

This is a radical and grim look, but I suspect they will be full of flowers by the beginning of August. How so? The renovation plan calls for a second pruning in June. I am not interested in long single branches with few and hugely ungainly flowers. Cutting back a long branch midway to the bloom time will result in side branching at the cut. This may result in a delayed flowering, but there will be flowers nonetheless. Next year they will regain their fulsome look.

Hydrangeas respond much more quickly to renovation pruning than other less vigorous shrubs. It won’t be long before they start growing out of this.

Knowing the best time to prune doesn’t necessarily result in action. I should have pruned these hydrangeas harder last spring, when the extra rows of plants came out. If you are like me, what I need to do in the garden routinely gets away from me. How indulgent hydrangeas are of less than stellar care is just one of the reasons to like them. Pruning times depend on whether they bloom on new or old wood. Since the Limelights bloom on new, or the current season’s growth, no matter how much or how little you prune, you are not removing flower buds. Just buds which will become leaves. So prune away.

 Pruning is a paradox. We sometimes prune back shrubs to limit their size, not realizing that a pruning cut, from a shrub’s point of view, is a call to grow. To branch out. A single pruning cut on a large sized branch results in lots of buds breaking in every direction below that cut. This late winter photograph of a hedge in my neighborhood tells the story. A hedge of substantial size was cut back for a number of years-at the height this gardener could reach. The result was lots of branching at the top, which eventually shaded out the branches at the bottom. Once the hedge became too tall to prune without a good sized ladder, the pruning stopped. The result is a rather interesting mix of bare sticks at the bottom,  dense branching at the mid level, and long unbranched growth at the top. Add to that mix, some weed trees that got a foothold in the hedge, and have grown to a large size. In this location, a very tall vase shaped hedge is probably a good idea. The traffic on both sides can come in and out the driveways under the umbrella shaped part of the hedge. I will be interested to see the summer look.To prune or not to prune-now is a good time to decide.