Pruning rhododendrons

What do they mean by dead heading?
To me, with rhodos the new shoots are usually coming from behind the old flower head when it dies, I usually would just take off the dead flower parts and let the new shoots grow.

When they say dead heading are they actually doing it as you would, say, a rose bush, and cutting back the flowered stem lower down.

 

Agreed @pete
From what I saw, no they did not, she simply pinched / twisted off the spent flower head

 

OK,so it's not going to keep the plant smaller and more compact , agree.

 

When we moved into our house, there were massive rhododendrons all the way along the boundary with the road, probably about twenty . Almost all are nice varieties of what I’d call ‘ordinary’ rhododendrons (there are several in the woodland that are fancier ones with big spiky flowers - when they flower, which isn’t often)
They were so large, we decided to take a ruthless approach, and cut them all down to about a metre from the ground. They all recovered, and have been flowering beautifully, but are now at least twenty feet high again. The main factor in our garden seems to be the lack of light. They are all on the north side of our woodland, and in the shade of some massive beech trees. Even the ones I’ve tried to prune properly get really leggy.
This is one of them in bloom.

 

Just keep on top of it @OwdPotter and take a view [pardon the pun!] every so often. I understand that it's very useful for you.

Interesting that the Google site mentions R. ponticum @Pete8 . They clearly don't know the devastation that thing wreaks, and keeps wreaking.
Hideous the problems it causes up here, don't know if it's so invasive elsewhere.

 

I've never seen one growing anywhere outside of gardens around here @fairygirl
But it's mainly arable fields around here and never seen one if a hedgerow either - I'm pleased to say

 

Interesting @Pete8 - just shows the massive differences [again] around this small country we all live in.
They were just doing an item in Wester Ross, on our countryside programme [Landward] about getting stuck into it all. It's a horrific undertaking due to the fact that it really has to be dug out, or it just comes back. If it's not 'managed' it just goes ballistic, so they've decided to clear it all, and then try and manage it, but it's a huge undertaking. I know the first time I went back to Glen Etive after many years, I couldn't believe the difference because they'd been shearing it to oblivion there too. You had to wade through tons of it - at waist to head height, to access many of the popular hills there.

 

We have several clumps of R. Ponticum in the garden. Very hard work to get rid of. It can be cut back to the ground, and still returns, plus any leggy branches that touch the earth, sprout roots and become a new plant. A lot of work with the mattock needed. I’ve managed to get rid of quite a lot, but some of it is growing on the steep slopes, and hard to get at. I’m loath to resort to chemicals, but might need to eventually. Unfortunately, I daren’t tackle some of it right now, as the surrounding undergrowth is popular with nesting birds.

 

R. Ponticum just doesn't stand a chance around here, I think its too dry most of the time or maybe the fact that although its not very alkaline we do have the chalk under our feet.

 

To me dead heading Rhododendrons means, breaking off the seed heads to allow the plant to put energy into growing not producing seed. You can break the heads off with care! after flowering but it is also easy to snap off the new growing point below the dead seed head. Best to leave dead heading for a couple of weeks post flowering so the growth below is a little less likely to break…..this advice is from bitter experience!
I grow over 3 dozen Rhododendron and therefore I have neither the time nor inclination to dead head altho I do on young plants. Once the plants, if bought at a decent size (say 5ltr pot size) have been in situ for a couple of years it really is not that vital to dead head. Mine flower very well without any dead heading.
As for pruning, yes most Rhododendron do respond to pruning altho some of the species ones don’t appreciate being cut back too much. If in doubt I delay prune, ie prune part one year and the other the next to lessen the shock.
Re hellish Rhododendron Ponticum, I am not unconvinced some of the less scrupulous sellers ( the likes of well know supermarkets!!!) do not sell cut price Rhododendrons which have been grated on R.Ponticum. I know quite a few folk who have bought white pink and red flowering Rhododendrons only for them to revert to hellish purple within a few years. You get what you pay for more often than not.

 

Locally it's hard to grow rhododendrons because our soil doesn't suit and we have rock hard tap water (plus live in a very dry part of the country where rain runs out quickly) but they have still taken a foothold and caused problems. They are mostly restricted to old pine plantations where the soil has changed enough to suit.

I think it was in the brecon beacons but we drove along a road with a hillside covered in the stuff. This road was more than a mile long, so I think it's a common thug there. There is a similar road in North Norfolk but not quite as long or dense in the coverage.