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.

Comments

  1. nella l davis-ray says:

    Thanks for the “radical, grim” photos. They give me nerve to try the same thing on my beloved “Pinky Winky” that I planted in 2009. According to the plant info it would reach 3-6 ‘ wide in about five years. It didn’t top out at 6. It’s more like 8 or 9. Pulling out the pruners this weekend.

  2. Marguerite says:

    Thank you for your posts, Deborah, they are always so educational. Have just hard pruned my very bushy Crab Apple trees , and I’m hopeful I have improved their health and flowering ability. As a followup the the previous Lilac question…. What would be a good strategy to keep a small lilac small going forward. ?

  3. stacie gombert says:

    Hi Deborah,
    I love your blog. Have you ever attempted pleaching? I’m thinking about adding lindens to my small courtyard but can’t buy them pleached in the U.S., so I’m thinking of attempting them myself. Any advice on the process would be great!

    • Deborah Silver says:

      Dear Stacie, the lindens on the driveway of my shop, Detroit Garden Works, are pleached. They look great. We grew them on until they touched, and then we pruned them into a pleached shape. best, Deborah

  4. Deborah Crabtree says:

    I have a hand-pruning business and I am passionate about it.

    I have a client who has several 20 year old, 12+ft, gnarly, multi-trunked pee gees that have never been pruned, until today when I pruned them. Many of the branches were dead and covered with lichen. The first one — I went after quickly with my pruning saw and pruned it to 3ft. Then I thought — I wonder if this old plant has enough vigor left in dormant buds to push out new growth. I more gentle with the others removing dead wood then pruned living side shoots to 2+ buds, ending up with 6 ft shrubs.

    Has anyone, Deborah and readers, had experience pruning old pee gees? I am anxious, especially the one I pruned first . Thank you!

    • Deborah Silver says:

      Dear Deborah, the will to live is very strong. The peegee you pruned down to 3′-it is anyone’s guess how it will respond. I am curious to know what happens! best, Deborah

      • Deborah crabtree says:

        I will let you know! Thanks for the response. One of these days I’m getting up north to visit your shop. Are any of your customers gardens ever on tour? It would be amazing to be able to see your work in person!

  5. VW garden says:

    I’ve just found your blog and have really enjoyed scrolling through many of your older posts. Your pots are especially inspiring, and I love your design insights from years of professional and personal experience.
    I have both Limelight and Little Lime, and I prune Limelight hard each spring. I’ve been pruning my Invincibelle Spirit hydrangeas hard each spring as well, but they’re growing in too much shade and get floppy no matter what. I’m planning to dig them up and pass them along to friends and plant Green Mountain boxwoods instead. I wish I could get mopheads to bloom well, but I’m at the bottom of a valley in Spokane, WA and our spring frosts just kill the buds. Even reblooming hydrangeas don’t manage to bloom before early fall frosts hit. Obviously a lot of breeding is happening for hydrangeas, so I’ll wait and someday there’ll be a good mophead that will actually bloom reliably for me!

  6. Susan Anderson says:

    Thanks. Pruned my hydrangeas yesterday, before the first massive rainfall. Should I give a first feeding now (I use Osmocote)?

    • Deborah Silver says:

      Dear Susan, I do not know where you are. I do not feed my hydrangeas until mid April or so. If you use osmocote, one feeding should be plenty. best, Deborah

  7. I am hoping all my snow will be gone this weekend, in which case, clean-up will begin. So much winter damage! My burning pile will probably double in size. I will prune as well as remove winter damage from ornamental trees and hydrangeas. Your hydrangea pruning strategy and recommendations are genius! I also love your block planting of hydrangea. A block of flowers must be a spectacular architectural focal point. Gardening brings much pleasure, even more so when learning and improving techniques. Thank you!.

  8. Debbie Qaltwr says:

    I had been told that Spring blooming shrubs shouldn’t be pruned until after they have flowered, or no blooms for that year. Is this correct?

    • Deborah Silver says:

      Dear Debbie, correct. Do not prune the spring bloomers until the bloom is over. The Limelight hydrangea blooms on the current year’s growth-in late July, for me. So pruning them now is fine.

  9. Jane cruickshank says:

    Thanks Deborah for the tutorial. The first nice day I shall prune…and prune.

  10. I am impressed with your pruning strategy! I look forward to seeing the result! I have an overgrown French Lilac. Should I prune it down to 4 feet tall or lower? I would appreciate any suggestions!
    I read all your posts. I love them! They are so helpful even though I live in Utah which is a completely different climate!
    Thanks so much!

    • Deborah Silver says:

      Dear Sharon, I would take 3 years to rejuvenate your lilac. I would cut a couple of the oldest and biggest branches to just above the ground every year. As to the timing-ask a nursery person in your area. For sure you will be cutting flowers off if you prune now. Lilacs bloom early for me. best, Deborah

  11. I always find it heartening that, after facing down a garden problem in the field, I open my inbox to find you battling the same difficulty, with the same sense of qualified optimism about the results.
    Thank you for the frankness of your posts, and your generosity in sharing your experience.

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