March 13, 2009

Hydrangea Pruning or Pruning Hydrangeas After Winter

How and when to prune hydrangea - this is an often asked question.

The best time to prune hydrangea is it in the spring, after the most severe frost is gone. Rather do not prune plants before winter, as it easier for them to survive when the real cold hits the garden. Not pruned plants and not cleaned perenninal remains give the shelter to many beneficial creatures. Look at this picture, how many ladybirds (natural aphids enemies) have been hiding from the cold under dead leaves on the flower bed.

In my 6 zone garden I prune hydrangea at the beginning of March. Depending of weather conditions you may prune hydrangea also end of February. I have in total 12 different hydrangeas and I will show you how I pruned them.

Recommended further reading Hydrangeas in the North: Getting Blooms in the Colder Climates

Hydrangea paniculata pruning
This one is easy, because it always flowers on current year growing stems. Therefore main role of pruning, as you can see, is to keep the proper shape and density of the plant. This is especially important when hydrangea paniculata is still young - pruning makes it more dense right from the bottom. The general rule is to keep 1-3 buds pairs on the stem.
In the first year it looked like this before pruning:

I pruned it low, at the level of 25 cm, in order to give the plant nice dense shape.
Next year I prune it 10 cm higher (1 buds pair)... (see how Hydrangea paniculata Limelight looks 6 months later, while blooming in August'09)...

......and additionally, I keep the inside stems higher, while outer stems are cut shorter. This will give hydrangea paniculata nice symmetrical shape. If your H. Paniculata is too large, you don't have to be affraid - just prune it as much as you need. It will show happily new leaves soon.

Hydrangea macrophylla pruning
(Bigleaf Hydrangea, French Hydrangea, Lacecap Hydrangea, Mophead Hydrangea, Penny Mac and Hortensia - all name same plant)
H. macrophylla does not require too much pruning, unless it is really required due to frost or physical damage of the plant.
First of all examine entire plant and check what is the situation with buds. From nature buds are naked, they do not have any protection against freezing - this is why they flower best in the zones = or lower than 7.
In lower zones, it shoud be planted in cosy corner, sheltered by other plants. It also may needs covering for winter. This winter mine were not covered, survived -20C, buds look so-and-so.
If you look at the buds and see, that they are completely brown - this means high possibility of damage - such buds must go!
If you see green inside of the bud.... like on the picture below........

- there is a chance that flower, formed previous year, has survived. So we spare this one and see if we were right.
Pruning of Hydrangea macrophylla is easy if you remember to not prune it too much - it will love you for this. Next thing you should do is to remove dead flowers, that are so ornamental in the winter garden - and look where is the nearest set of green buds and cut 1 cm above it. That is all you need to do to keep it ready for the happy summer.

Hydrangea aspera pruning
It does not require pruning and actually it doesn't like it. This is large shrub (up to 5m), so you need lot of space to make it real stunner.

Hydrangea arborescens Annabelle
Flowers form on current year stems, so in general you may prune it to keep the shape of the shrub. However don't prune it too hard if you don't want to stalk your flowers. Fresh stems are not rigid enough to hold big, white flowers. I make rather cosmetic pruning - only if I see dead stems or want to change its shape. As you can see this hydrangea does not need pruning this year.

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Recommended further reading Hydrangeas in the North: Getting Blooms in the Colder Climates


Lisa at Greenbow said...

Intersting tutorial. I usually don't prune anything off my hydrangeas until they show me what is going on. Then eventually I cut out the dead limbs and flowers heads from last year. I guess I was doing it right.

CanadianGardenJoy said...

Hi Ewa ! Thanks for the reminder about what I am supposed to be doing with my Hydrangea , eventually when the Frozen North here THAWS !! LOL

Tara Dillard said...

You are brave Ewa. Hydrangeas are a several week class. Penny McHenry, founder of the American Hydrangea Society said, Make a rule for hydrangeas & they'll make a liar of you.

You're right each year is different for timing hydrangea pruning.

Penny pruned late winter too. The University of Georgia agriculture school did trial studies of pruning mophead hydrangea. Result, prune after flowering in late summer.

Penny tried that and had complete failure. She went back to her experience of 3 decades. Pruning as you described in your post.

Being intuitive I have always copied Penny's pruning. Except her foray into late summer.

Plants don't read books. I copy what works in other people's landscapes.

Garden & Be Well, XO Tara

garden girl said...

This is very helpful Ewa. I've had hydrangeas in past gardens but none here yet. This winter I grew some Annabelle and Endless Summer cuttings and ordered an oakleaf. Since I haven't grown these varieties before, I'll refer to this tutorial when it's time to prune them for the first time.

I especially appreciate what you said about pruning Annabelle, since I've read they should be pruned to the ground each spring. What you're saying makes much more sense to me. I want them upright, not so floppy as I've often seen them.

joey said...

Excellent Ewa! I also have Oakleaf Hydrangeas (H.quercifolia) that bloom on old wood. In natural settings, best left unpruned unless for dead limbs and a bit of shaping after flowering.

Ewa said...

Dear Lisa,
If they grow the way you like it, it is fine to leave them without pruning. If they look fine, you do the right thing.
I pruned my young H. paniculata, cos I saw few of them in other gardens, which were not so nice, because they were not trained from the beginning.

Ewa said...

I have a feeling, that sometimes things are made more complicated than they should be.
I also have a feeling, that sometimes things are presented on purpose as complicated, so they can't be understood.
I try to keep as many things as possible, as simple as possible.
I studied the subject a lot, cos I love Hydrangea and I was trying for pretty some time to figure out what is best for them.
I know I do not cover everything, but basics - yes.
In my zone I can't prune mophead after they flower, because they flower until November - in the meantime I rarely deadhead the gone flowers.
About timing, in general I think that for H. paniculata, time when crocus is flowering, is the last time - any suggestions you have?

Lona said...

I love hydrangeas and have several around in the yard. You gave a great tutorial on pruning. I will have to get after mine here soon.

Barbara said...

You're right with what you wrote about the pruning of H. Annabelle. According to books one should cut them right down...what I always did. But this year I forgot it and I do hope it will come out as you said. The stems should be much stronger now for the big flowers to hold. I wonder whether it really works ;-) !

Pat said...

Eva, it looks as if my Hydrangea Paniculata has suffered frost damage. We have had a bad winter and some late frosts, just when the new leaves were out. Will it survive, do you think? Is there anything I can do to help it?

Thanks, Pat (Ireland )

Ewa said...

H. paniculata is very hardy. Up to 35C - have you had more last winter?
Maybe there is another reason of the problem. Any pictures you can share?