Rhododenrons

Think I need some advice, My Rhododenrons are looking decidedly fedup they are 4 years old
Mrs A T de la mare white, and Ightham yellow this one sulks in the cold so I, have wrapped it in fleece ,Looked up to see if I could find the cause of the fedup ness reckon it could be chlorosis the soil here is very sandy, well in my small garden I have put loads of compost, and growmore, l etc,but they dont look very robust. The local wild ones near by are huge,any suggestions would be most welcome , they were expensive and from a reputable grower and are so beautiful.

 

Hello rosietutu, Can you still get hold of Miracle-Gro Ericaceous Feed in the UK? Mixing up a big watering-can-full for each shrub and watering it on slowly so it penetrates the rootball will sort out any chlorosis. (Other ericaceous feeds are available ;-)) The other possible reason for fed-upness could be vine-weevil infestation. Are any of the leaves looking notched along their edges? If so, you'll need to drench the soil and rootballs with Provado.

 

You could also try a good mulch of Ericaceous compost

 

Certainly I would stop feeding Growmore as pretty sure that contains alkali which Rhododendrons do not like. To be honest they don't really respond that well to being fed in my experience, I don't feed mine many of which (both species and hybrid) I have had for over 20 years. What they do like is plenty of water but free draining soil. Rhododendrons are surface rooters and dislike their roots being disturbed too much so best not to weed right around them. A thick mulch of bark chip or similar is much appreciated being good as a weed suppressant and reduces evaporation in dry periods. If possible post some photos of the plants leaves especially as they might shed some light on the problems especially if Vine Weevil is the culprit.
I'm wondering if other gardens/woodland in your area have healthy Rhododendrons? If they do then the problem is specific to your garden, if not then it might well be that the Ph of the soil in your area isn't suitable unfortunately. If this is the case then I'd recommend either completely changing the soil in the bed to Peat (no doubt not very PC these days!) or some other Ericaceous growing medium or perhaps lift the Rhododendrons and continue to grow them in big tubs with Ericaceous "soil".

Again from experience my yellow Rhododendrons aren't too keen on living here in a fairly cold part of the world! Perhaps there are very hardy yellow varieties, personally I now steer clear of that colour and make do instead with yellow deciduous Azaleas which do well here.

 

Ha Ha love the bit about the water !!! I have purchased this morning Gro-Sure Ericaceous Liquid plant food I will give that a go, interesting info about Growmore tho and the other thing I throw about is Chicken Maure pellets I do get a good crop of runner beans and raspberries. I have the tinyest garden you ever saw and I like to keep on top of it, tho not so agile now coming up 83 so digging/moving plants are out of the question just take a little stool into the garden and poke about weeds and such like with hand tools.and its raining again...

 

Just to double check what Silu said: Are there Rhododendrons and Azlaes in other people's gardens near you? If not its probably the soil pH that si the problem.

If you are already at the point where the leaves are yellow-ing I think I would go for something more potent than an ericaceous feed - e.g. Sequestrate of Iron / Chelated Iron. I would also put a small handful of Epsom Salts (i.e. Magnesium boost) around each plant. Buy that at the garden centre, much cheaper (for bulk) that buying at a chemist!!

 

Thank you I did wonder about iron, Nealy all of the surrounding shrubbery here are wild Rhododendrons 20feet high they dont seen to have a problem, reckon it will be a bit like pedigree dogs Oh I used to breed them! the finer the pedigree etc...Its raining again perhaps water lilies might be a better choice.

 

You soil is definitely suitable then! Yes, I would agree with the Pedigree comparison. Best to grow varieties known to be Good Do'ers