Rhododendron Leaf Droop and Brown leaves - Dying ??

TerrysWorld · June 2021

One of my Rhododendrons appears to be dying.

They along with a Camelia and Azalea are grown in containers due to our alkaline soil.
During the winter I place them near a north facing wall of the house for protection and at all times they sit on small wooden feet raising off floor all year round.

Now being spring/summer they are placed on the patio seeing afternoon sun, shade otherwise.

From mid-may I have noticed the leaves drooping on one of the plants assuming this being from a late frost. On all the containers there is 25mm layer of grit on top of the ericaceous soil. Prodding my finger into the soil, it feels moist. I regularly feed with a liquid feed for them every 7/10 days. It has unopened buds from last year which are starting to drop along with the leaves turning brown. I've checked for any signs of the vine weevil eating the leaves, nothing. I've had this plant some 4 years with no problems.

Is it too late to save the plant by moving to a larger container with fresh soil with maybe added grit for drainage or adding a mulch layer or even moving it totally into shade at this time of year from the heat/sun to rest.

Thanks

luis_pr · June 2021

During the early Spring, azaleas, camellia japonica, hydrangea and rhododendron leaves have no problems but once temperatures begin to exceed about 29C in mid or late Spring, the leaves may begin to show symptoms of heat stress (including wilting/drooping). I have to plant all of these plants such that they get sun until 10-11am only and then shade during the rest of the day (afternoon and evening).

Feel free to transplant or better yet, move the container to morning sun only or dappled sun. Since transplanting will disturb the roots more than moving the pot, monitor the plants more often this summer if you transplant and test the soil daily for dryness by inserting a finger to a depth of 7-10 cm. Then water if the soil feels dry or almost dry.

I grow mine in the ground. Although my soil is alkaline (pH of 7.6), I prefer to amend the soil regularly and, while I do not aim to get the pH acidic, they tolerate the pH if I amend in Spring and at the end of the Summer with garden sulfur.

TerrysWorld · June 2021

Hopefully to the rescue by putting it in the shade by day to recover. 🤞

Fairygirl · June 2021

It sounds like they've become dehydrated during the dry spring, but also last year when buds were forming. The crucial time is late summer for that. If they go short of water at that time, they can't sustain the buds and open them properly.
I wouldn't keep feeding it though. If it's in a soil based medium [ie not just compost] then it's really just watering consistently that's needed, with maybe the odd foliar feed.
Even in rainy weather, the rain doesn't always get through the canopy of foliage, so it's very easy for them to dry out. Bark is a better mulch than gravel too.
Have you potted them into bigger pots too? It's quite difficult to keep them happy in pots unless they have adequate room to spread. They're shallow rooted, but the root systems [generally] are broad.
There's really no need to protect them in winter as such, but a north facing aspect is the best one for them if in pots, especially if you don't have great conditions re climate for them. They'll dry out less readily in a shadier spot.

TerrysWorld · June 2021

Thanks,
Worried now, as when moving them to hide from the heat of the midday/afternoon sun.
Noticed some leaves are going brown and crisp.

I used to use Bark but it tends to dry out from week to week watering and tends to gets blown away.

Any advice for best foliage feed, would spraying with tomato feed help with the dehydration. ?

Fairygirl · June 2021

Tomato food is for flowering or fruiting plants, so no, it wouldn't be suitable. Seaweed is ideal, but foliar feeds should only be done on cool/cloudy days, or after sunset when there isn't going to be any chance of sun on foliage

If the bark is drying that readily, it shows there isn't enough moisture present. In a shady spot, it shouldn't dry out quickly, even in warmer weather. Do you mean you're only watering once a week? That isn't anything like enough for potted shrubs in dry weather.

TerrysWorld · June 2021

Thanks,
Its what I've read for container (50cm dia pot) grown Rhododendrons to be weekly and the ericaceous soil feels damp by prodding a finger.

I will spray with a seaweed feed.

thanks again

Fairygirl · June 2021

It would depend on the size and maturity of the plant as to how often you water, as well as all the other factors -ie soil, climate and position. It's one of those 'how long is a piece of string' questions, because watering needs to be as frequently as the plant needs it.
Once a week for a potted rhodie wouldn't even be enough here in drier or windier spells,. We have a cooler damper climate which suits them, but once you put them in pots, it becomes a different matter. There's a limit to how much moisture they can access, and they're more easily affected by changes in weather. Sun and wind dry out pots very quickly too

Rhododendron Leaf Droop and Brown leaves - Dying ??

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