Rhododendron survival and drought

deanna in ME Barely zone 6a, more like 5b

3 years ago

So far in September we have had 0.16 inches of rain. We did get about 3" in August, which is better than many areas. I am now concerned about the garden entering winter with bone-dry soil. I planted many small rhododendrons in Spring 2018. Fall was perfect with ample moisture until the first frost. Horrendous winter after that. They barely survived the winter of 2018-19. I thought several could never recover, but they have ALL recovered, although some, including Nova Zembla, have still not flowered, which surprises me. Last fall was wet, so they all entered the winter with excellent soil moisture after a summer of tender loving rejuvenation. Last winter was mild, as well. They are about to enter their third winter, but the drought conditions are significant. Even getting deep watering done is difficult. I'll put a trickle of water at the base of the trunk, but the soil is so dry the water doesn't seem to be penetrating all areas of the rootball well. In addition, I have to be careful about watering since we are on a well and I don't have an endless supply of water. Last year they all got winter burlap protection and will get it again this year.

I believe my evergreen large-leafed rhododendrons need adequate moisture or their leaves will desiccate in winter. What about the small-leafed deciduous rhododendrons? I have some small-leaf evergreen rhododendrons that I don't think keep their leaves well, like Blaauw's Pink.

Some things will survive the drought, but won't be happy. I'm concerned my rhododendrons won't. What's a good plan this fall to prepare the rhododendrons and azaleas for winter?

My varieties:

Larger leafed evergreen rhododendrons 'Percy Wiseman', 'Nova Zembla'

Smaller leafed evergreen rhododendrons 'Ken Janeck', 'Blaauw's Pink', 'Tow Head', 'Rosebud'

Deciduous rhododendrons 'Mt St Helens', 'Mandarin', 'Gibraltar'

Native rhododendron 'Labrador Tea' (which like boggy conditions--lucky me)

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Comments (3)

luis_pr
3 years ago
Have you done a soil test to see if you have any mineral deficiencies? If rainfall is the almost only source of water and you currently have so many soil moisture related issues, this location may not allow for many or for large rhododendrons/azaleas. If there are no soil mineral issues, I would try dwarf/miniature rhododendrons only that will not need as much water. Or other plants.

You can prepare the plants by pruning dead wood, making sure they have 2-4" of mulch and acidic soil. and do no fertilizing now since we are too close to your average date of early frost (so you want the rhodies getting ready to go to bed and not be in "grow mode"). Of the varieties that you mentioned, Rosebud is zone 6 in some online sources, which is not winter hardy enough if you think 5b is your correct usda zone.
deanna in ME Barely zone 6a, more like 5b thanked luis_pr
NHBabs z4b-5a NH
3 years ago
I take a couple of gallon jugs and put a pinhole or two and then set them over the rootball. If you do this every day for several days and then try the hose trickle, it may have gotten the soil moist enough deep enough so there will be some absorption. You do want all your Rhodies, both large and small leaf to go into winter well hydrated.
deanna in ME Barely zone 6a, more like 5b thanked NHBabs z4b-5a NH
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deanna in ME Barely zone 6a, more like 5b
Original Author
3 years ago
Luis, thanks for the information. My soil is currently very conducive to rhododendrons. I have some older bushes that have got to be over 10 feet tall. They are thriving in the soil, but the winter of 2018-19 was devastating for many plants. People lost 20 year-old rhododendrons that winter. I’m just glad mine did survive, even if they hung on by just a thread when winter was over. What I really need now is guidance concerning fall is about watering. (And, yes, I know I am cheating nature with Rosebud. Technically we are zone 6a, and I was hoping its spot was a little protected, allowing it to thrive. So far we’ve made it three summer, with many flowers this year.) I definitely need to add more mulch before winter, so thanks for the reminder.

NHBabs, that idea sounds perfect. I’ve got plenty of milk jugs! I woke up this morning to the sound of rain, and was thrilled to see the weather forecast had changed to rain this week. I’m hoping the foggy weekend and gentle rains today have softened the hard surface soil, allowing rain in the coming days to really soak in!