Pruning rhododendrons

I’m not a viewer of beechgrove but caught the end of it last week whilst waiting for something else. So I wasn’t really watching it.
My attention was caught by one of the presenters who I’m sure said to ‘deadhead rhododendrons to maintain their current size’, or something along that line.
I have several rhodo’s around the place, and they are getting big.
As new growth appears to emerge from below the spent flower, I don’t really see how deadheading is going to restrain the plant’s growth?
Is that correct or did I mishear or misunderstand what was said?

 

Dead heading as you say will not keep the plant small in my opinion.

You can prune directly after flowering.
Light pruning will hopefully not cut down on flowering too much next year.
Heavy pruning probably will result in lots of leafy growth for the first year at least.

 

You can usually cut them back quite hard without any problem, and you can also take some stems right back each year, over a few years, to overhaul the entire shrub if you prefer. That means you still get flowering. Cutting back hard means no flowers for a while, and can sometimes be tricky depending on the type and your conditions, as it can be... a bit fatal if you go too far.....
Any pruning is best done after flowering, as already said.
It's always a good idea to check them over to see if there's any old, dead ones which you can remove, or any that are crossing and rubbing. That helps maintain the general health.

Deadheading won't really do anything other than removing those spent heads. If you take a little bit more stem it'll help to keep them a little smaller than they would naturally be , but not by any noticeable difference, because they'll still grow through the season, sometimes by quite a bit, depending on the variety.

 

There was a mature rhododendron in the garden when I moved here nearly 40 years ago.
Whenever it gets to about 12ft high and wide I cut the whole thing back to about 2-3ft.
All that is left are thick bare stems with barely a leaf in sight.
Within weeks it sprouts again and after about 5 years it's back to 12ft, so I repeat the process.

 

Yes - some can be fine, and others won't do so well @Pete8 .
There was a bright pink one here when I moved in, and I was undecided about it. It had really nice foliage though - rusty brown underneath. I wanted to move an oak leaf hydrangea there, so I cut it right back. That saved having to dig it out....

 

Pruning if the bush is thriving will do no harm; it will however not renovate weedy, sickly examples. To kill a vigorous rhody is not easy. any root left remaining will likely strike again.

 

Thanks folks,
When I said they are getting big...
This was 2018

This was 18:20

How big can these things grow?
This is probably about 12"x12" now @Pete8 so that kind of cut back might well be the only option if it gets much larger, cos there is no way i'm getting up on top of that with my knees.

 

Mine is back to that sort of size again @OwdPotter
I can't be sure when I last done the 'deed' but I think it was about 5 years ago.
Here it is now - you can just see the dead flower spikes (top centre) the centre of the pic - just to the left of my rambling rose, so that's about 12ft again.

I won't be deadheading it

 

Mine was certainly healthy - they grow like weeds here due to our climate. It wasn't going to reappear though- after being cut hard right back to the base.
How big do they grow? How long is a piece of string @OwdPotter ! There are hundreds and hundreds of varieties. If they like the conditions, they can get massive.
If it's too big for your site, and you're struggling to manage it, you have nothing to lose by cutting it back. If it doesn't survive, you can put something easier in it's place. You can always take some of it back - the bits you feel confident in reaching, and then see what happens.
Or - would someone help you with a ladder and a big saw? I used to do my Dad's hedge for him [20 odd years ago] when it was way too big for him to manage by himself. It didn't bother me being up a ladder, reaching across the massive spread of it etc, at that age, but I would hesitate a little bit more now if I had no one to help me.

 

Ahhh I’m glad I’ve found this! I heard the below on gardeners question time a few weeks ago! I have a friend who’s inherited a very mature garden with her new house and there’s a couple of old rhododendrons that are tall but with flowers and leaves just at the tops of the branches. We were wondering if they could be pruned down but according to GQT not all can be cut back!


Q - I have some very colourful Rhododendrons in my garden. They are getting very leggy and have long woody branches with a bud at the end. How can I prune them?

Christine – some Rhododendrons can be pruned and some can’t. To find out, push your hand along the bark about a foot (30cm) from the soil. If you feel bud initials that are like small grains of rice then you can prune it. If you don’t feel them, you will kill the plant by pruning back.

 

I’ve just watched the Beechgrove program and the presenter said the following

“Dead heading Will keep your plant nice and compact and stop that leggy growth”

all ok if your rhododendron is quite small to start with!

 

An interesting post, thanks @Millie16

Google lists some of the varieties that may not respond well to pruning.
Looking at the varieties that may be at risk, they look different to most of the types I see locally.
Mine is a bog-standard purple one that was planted long before I arrived.

Here's the info-

Some rhododendrons can be pruned, but others shouldn't be heavily pruned or cut back to the trunk. Rhododendrons with smooth bark or large leaves may not respond well to hard pruning, while those with rough bark, like Rhododendron ponticum, often tolerate it well.
Here's a more detailed explanation:
Rhododendrons that can be pruned:

• Most varieties: Many rhododendrons can be pruned to remove dead or diseased wood, maintain shape, or encourage new growth.
• Deciduous azaleas: These often respond well to hard pruning.
• Rough-barked rhododendrons: Rhododendron ponticum and similar species tend to regenerate well after pruning.

Rhododendrons that should be pruned with caution:

• Smooth-barked rhododendrons:
  Varieties like Rhododendron thomsonii and Rhododendron barbatum may struggle to sprout new growth from the trunk if cut back severely.
• Large-leaved rhododendrons:
  Many large-leaved species, like Rhododendron sinogrande, may not respond well to being cut back to the trunk.
• Small-leaved cultivars:
  Some small-leaved rhododendrons may not require maintenance pruning, especially if they don't set seed after flowering.

Pruning techniques:

• Remove dead, diseased, or damaged wood: This is generally recommended for all rhododendrons.
• Deadheading: Removing spent flowers encourages new growth and can be helpful for many rhododendrons.
• Shape and maintain natural form: Pruning can help control the size and shape of rhododendrons.
• Rejuvenation: In some cases, severe pruning can be used to rejuvenate an old or overgrown rhododendron, but this is best done with caution and may not be suitable for all varieties.
• Consider the flowering time: If you prune rhododendrons that bloom in spring, do so after flowering to avoid removing flower buds.

Important notes:

• Pruning timing:
  Most rhododendrons can be pruned in late winter or early spring, or after flowering, according to RHS.
• Soil and nutrients:
  After pruning, particularly if it's severe, it's essential to mulch, feed, and water rhododendrons to encourage new growth, especially if the soil conditions are poor.

 

Lots of good info there thanks Pete8!

 

Thanks @fairygirl
I don’t mind it as a large plant, it provides visual screening from the road, and as a useful side is now tall enough to block the light pollution from the street lamp from shining into the lounge window.
I have trimmed it back up to about 2m for access, so good for another year at least.

 

Hmmm, this is what started it and I think we all seem to agree that it won’t