Hi luis, My Rhodies are new this year, and the sun they get is in the afternoon-evening We had a long hot Summer here this year, and not much rain, I did water my Rhodies every two or three days. I live in zone 5, which should not be a problem.
Rhodies should be planted to receive morning sun only in the summer, except in areas close to the border with Canada where they sometimes can withstand full sun. Leaves can get a scorched look when they get too much sun or when they get periods of dry soil & moist soil. Evergreen rhodies should now be sleeping so their leaves will look as they did before; therefore you will not see an improvement in the way they look until they leaf out in Spring.
The sun this time of the year will not harm the leaves much so just keep them well mulched and keep the soil evenly moist at all times when the ground is not frozen. Watering once a week or once every two weeks -depends on your soil moisture- is ok. Since they are not active now, consider this time a good time to transplant to a location where the leaves do not get afternoon sun in the hot summer months. But leave them there if you think the scorched leaves were due to moisture problems.
Rhododendrons can sustain root damage from heat and limp along for a few months before they show signs of dessication such as wilting.
Here are some of the more common causes of Rhododendron suffering or even death.
1 The root ball of a potted rhododendron is often growing in a circle if it is in the pot for a long time. The roots cannot reach out for the water and nutrition, and the plant is severley stressed. Before you plant, you should take the plant roots out of the pot and free them by raking them out from the tight ball.
2 There are some Rhododendrons may exist in full sun but even these do better in high shade,
3 poor drainage will easily kill a rhododendron
4 don't fertilize a newly planted rhododendron. IT has been heavilly fertilized in the Nursery you bought it from. More fertilization will burn the roots.
I hope this helps
Thanks Arfitz, yes that does help, but I did do things wrong. My Rhododendrons sat in pots for over a month at my home before I planted them. I did not do much with the root ball either, and another bad thing I did, was I fertilized the shrubs very heavy. Clumps of the leaves would droop, so I would cut some off, and then the same thing would happen again.
It's a wonder their not completely dead yet. Hope they can be saved.
I'm going to ditto arfitz and emphasize what he said. I massacre the rootballs when I plant mine. I go all around the rootball with a hand-held 3-pronged soil scratcher whatchamacallit.
Drainage. Don't plant them in a hole. Plant them on top of the ground (weed and grass free of course) and put a good soil for rhodies around them up to where the roots meet trunk. Mulch with pine needles. I have excellent results with this method.
If I do feel like fertilizing any of them I do it during winter or early spring and just lightly dust their root zone with cottonseed meal only. Not sure if it makes a difference but it won't burn their roots.
Also make sure you don't let the rootball dry out before it makes new roots in the surrounding soil. If you see a newly planted rhodie wilting that is more than likely the reason. The surrounding soil can be moist and the root ball dry as a bone at the same time.