I can't explain your leaf drop without further information, but rhododendrons have a very shallow root system that should be kept moist. A good layer of mulch would be good, and acidic soil, bright shade/dappled sun, no direct afternoon sun.

I wouldn't recommend trying to move the rhododendrons unless you have some idea of how large they were before being severely pruned. Trying to get a big enough root ball is going to be something of a challenge.

If the branch stumps were thick, say more than 2 or 3 inches across, then moving them is unlikely to be successful I'm afraid. Hard to say why all the leaves fell off earlier in the year - its a pity you don't know why they were cut down in the first place, perhaps they had some problem and whoever cut them down thought that might be the end of them.

I was thinking that too, Bamboo. Perhaps it is R.ponticum
& not a variety.

Thank you all for your quick replies! In terms of the leaf drop I suppose it was really more new branch drop. The whole branches fell off with leaves attached! ? No browning, no apparent reason, they just fell off at the joint! The previous owners cut everything (cherry laurel, japonica acuba, forsythia) down to stumps before putting the house on the market so no clues there.

I'd say the stumps were at least two inches so looks like they are staying put... Possibly unless they are R. Ponticum... I've just looked R.Ponticum up and ours do look like them to me but from what I've read it seems they may not be too good for native species or bees. Is this something to be got rid of? It seems a shame as they are so pretty but want to try to grow things that are good for nature.

I'll try to upload a picture. If someone could tell me if it looks like it is R. Ponticum then that would be very much appreciated.

Unfortunately, its next to impossible to tell if its R. ponticum unless the flowers are present - R. ponticum growing in gardens isn't too much of a problem, the problem is its ability to seed itself far and wide, particularly in the wild. In gardens, it can be kept under control.

There is, though, a connection between phytophthera ramorum, a serious fungal infection, and R. ponticum, but again, this is more of a major problem in the wild rather than in gardens. However, since you've had a branch or two fall off in the summer, you might want to check the link below for symptom description of both phytophthera ramorum and p. kernoviae, in case your plants are infected - you'll note that cases of these diseases are still notifiable

https://www.rhs.org.uk/advice/profile?PID=329

Thanks Bamboo. I'll have a closer look tomorrow to see if they are showing any other signs of being poorly. Fingers crossed it may have just had something to do with the funny weather we had earlier this year. They tried to flower again in September so seem confused!

I've uploaded some pics of the bush and flowers. Flower is my profile pic :)

If they are R. Ponticum do you know if they would usually respond ok to pruning? They seem to be growing fairly quickly so I'm thinking at some point they will outgrow their space.

Thank you for your help.

The flower looks typical of R. ponticum to me and, personally, I'd remove and plant some better favoured Rhodos! You are going to constantly struggle to keep this under control and there are so many species why keep something that wants to grow like a thug?

Not sure its R. ponticum - the flowers look a little too pink, ponticum flowers are distinctly mauve or lilac in colour. One thing I can see though, and that's vine weevil damage on the leaves - those notched bits on the edges of the leaves are where they've had a go. Shouldn't be too much of a problem in open ground, but if you've got any plants in containers, you should keep an eye on those and you may need to drench the potting compost, see info below

https://www.rhs.org.uk/advice/profile?PID=234

As for pruning, if branches are falling off on their own, sounds like they're 'pruning' themselves, but yes, you can cut back, but don't do it every year. If they get out of hand quickly, it might be better to remove them and plant something else, or a smaller variety.