Can anyone tell me what is damaging the leaves on this evergreen Rhododendron
Hi spring jean, is it merely discolouration? It's quite difficult to see on your photo. If so, it might be lacking nutrients, either because the rain's washed them away or because it's not compatible with the soil/compost it's in. According to the RHS plant finder website, they like 'moist, humus-rich, acid soil but will not tolerate deep planting'. So, in pots they usually need to be in ericacious compost. And does it need potting on in fresh compost and a slightly bigger pot?
Give it a dose of sequestrene. It won't turn the current leaves darker green but new growth should be a lot healthier. If you live in a hard water area use rain water when possible or else retreat with sequestrene every 8 weeks through to autumn.
So, when the leaves are yellow on any plant will sequestrene help? I have a few plants that have yellowy leaves (including a digitalis) and I think it's due to all the rain washing the nutrients away (the digitalis that were in other drier places look healthy). I was going to scatter blood fish and bone around but is that inadvisable?
Yellowing (Chlorosis) is due to lack ofnutrients . this can be because the soil or compost is short of nutrients, or because of waterlogging which can prevent nutrient uptake, or, in the case of acid loving plants, it can be because the soil is alkaline, which stops the roots from absorbing the nutrients. Sequestrene contains nutrients in sequestered form, which is techie for a form allowing them to pass into the roots. Basic sequestrene only has sequestered iron, the main cause of chlorosis. Sequestrene + has a lot more nutrients in this form.
Digitalis is OK in alkaline soil so use something like miraclegro for a quick pick me up.
Oh blast, I just bought the basic sequestrene online and now wonder if I should have bought the +. However, it won't go to waste - a friend has a magnolia with the same problem as the rhododendron so I can give it to him. But that's great about the miraclegro idea for the digitalis - I'll do that, thanks.
I was given this as a gift last spring in a pot, I planted it in this big tub soon after also using ericacious compost. I wondered if I fed it with plant feed ericacious that might help
Are you in a hard water area?
Ericacious feed should help, in a pot it will need feeding anyway. Rain water is best for watering. Every year you should scrape away a bit of the top compost and give it some new ericacious compost. I think it looks hungry.