Hardy rhododendrons
Moderators: lucky1, Alchris, Kansas, Wes North Van, Laaz
Hardy rhododendrons
Does any one grow rhododendrons in zones 5 6 7 8? I see rhododendrons everywere. Some look like woody bushes or others look small plants. In florida rhododendrons were big trees.
Rhododendrons
Hi Donny
My first outdoor plant craze was cacti,then rhododendrons.
My favourites are the big leafers.
Do you want some pix?
My first outdoor plant craze was cacti,then rhododendrons.
My favourites are the big leafers.
Do you want some pix?
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- Sprout
- Posts: 72
- Joined: Sat Nov 19, 2005 3:33 pm
- Location: Boise, Idaho, USA (zone 6b-7a)
I am growing some
People tell me "You can't grow rhododendrons in Boise!" But I can and do. Generally I plant hardier varieties usu. to about zone 5 or 6; the zone 4 Rhody's (PJM, etc.) do not appeal to me, and the zone 7 varieties do not seem to do well here. (Other plants hardy to zone 7 do fine here for the most part though.) My rhododendron beds are supposed to be a little taste of Seattle, maybe minus the latte kiosks. Some things I have to do here:
-They must get at least partial shade here; if they get any afternoon sun in the summer they are likely to suffer leaf burn. Boise summers are not exactly conducive to rhododendron gardening; the air is hot and dry and the sunshine is intense and unrelenting. (In case you were wondering, I have tried a few azaleas but after fairly decent success they were destroyed by my dog, trying to find her stash of pork bones. I will try them again though.)
-I also have to water them in the winter; many places that I have them are under the eaves and do not catch the rain and snow. I will actually hook up the hose again to water the Rhody's on a mild day.
-I usually do not use the sprinkler to water my plants but it seems to do good for my rhododendrons, especially on hot summer days. The shady sheltered spot I have my main bed in keeps too much it from evaporating, yet enough evaporates to create a cooler, more humid microclimate for at least the rest of the day.
-Treasure Valley soil is not as bad as one might think for rhododendrons; yes it is slightly alkaline but it is nutrient rich mineral soil. All it needs is some peat/manure/compost/other organic pH lowerer. They enjoy plenty of ammonium sulfate too. The silt-clay mixture holds water well, so I only have to water about once every seven to ten days except during the hot parts of the summer.
-Mulch is a must, even more so than in wetter climates. In the summer, if my Rhody's are not mulched they will wilt every day in the heat and require daily water. After I mulched them they quit wilting and only needed water about every two or three days, even when temperatures got above 100 F. Last summer they did not wilt even when the high was 108! In the winter the mulch protects the soil from drying out too much from thawing and re-freezing.
It is obvious when driving through town who knows how to grow Rhody's in Boise and who does not. Well taken care of Rhody's can get to 4 or 5 feet tall here and stay very healthy; others will stay about 2 feet tall and lose a lot of leaves to the heat; they often succumb within a couple of summers.
-They must get at least partial shade here; if they get any afternoon sun in the summer they are likely to suffer leaf burn. Boise summers are not exactly conducive to rhododendron gardening; the air is hot and dry and the sunshine is intense and unrelenting. (In case you were wondering, I have tried a few azaleas but after fairly decent success they were destroyed by my dog, trying to find her stash of pork bones. I will try them again though.)
-I also have to water them in the winter; many places that I have them are under the eaves and do not catch the rain and snow. I will actually hook up the hose again to water the Rhody's on a mild day.
-I usually do not use the sprinkler to water my plants but it seems to do good for my rhododendrons, especially on hot summer days. The shady sheltered spot I have my main bed in keeps too much it from evaporating, yet enough evaporates to create a cooler, more humid microclimate for at least the rest of the day.
-Treasure Valley soil is not as bad as one might think for rhododendrons; yes it is slightly alkaline but it is nutrient rich mineral soil. All it needs is some peat/manure/compost/other organic pH lowerer. They enjoy plenty of ammonium sulfate too. The silt-clay mixture holds water well, so I only have to water about once every seven to ten days except during the hot parts of the summer.
-Mulch is a must, even more so than in wetter climates. In the summer, if my Rhody's are not mulched they will wilt every day in the heat and require daily water. After I mulched them they quit wilting and only needed water about every two or three days, even when temperatures got above 100 F. Last summer they did not wilt even when the high was 108! In the winter the mulch protects the soil from drying out too much from thawing and re-freezing.
It is obvious when driving through town who knows how to grow Rhody's in Boise and who does not. Well taken care of Rhody's can get to 4 or 5 feet tall here and stay very healthy; others will stay about 2 feet tall and lose a lot of leaves to the heat; they often succumb within a couple of summers.
Who wouldn't want free pie and chips?
Your right about partial shade because we get very hot in my area and if placed in full sun they could get burn but in boise its much hotter. The only record I saw was 41C I planted my Rhododendrons yesterday and got good results.People in trenton mulch theirs because they heard they Rhododendrons can die in wet cold. Even in severe heat I see them wilt so people mulch them. Our summer normal is 26C but it always goes higher. Last summer we had tempuratures 35C non stop. They tend to do good in our soil. In 1982 I was at school and had a garden the soil depth was only a ruler and a half People put in Rhododendrons and got to wet and froze up freezing rain too and completely dead. Not deep enouth to put in anything. So you are very right.Rhododendrons do not get that big here but atleast 7 feet tall bushes.
- Wes North Van
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Rhodos
Rhodos have to be the most common tree and shrub in Vancouver. Some grow into large trees. My neighbour has on that is 15' tall. My largest is over 10'. I probably have 20 different rhodos in my yard. They like acidic soil so I always add peat moss to the soil and fertilize them just before and after they bloom with miracid. Water well in the summer. Even here with warm not hot summers they need lots of water.
There are native large leaved rhodos in the PNW.
Here are a few pics.



There are native large leaved rhodos in the PNW.
Here are a few pics.



Wes North Vancouver Zone 8b/9a
Keats Island BC Zone 8a
Palm Springs CA Zone 9b/10a
Keats Island BC Zone 8a
Palm Springs CA Zone 9b/10a
Great photos
Rhododendrons will not grow into big trees in zone 5 & 6. But there is alot of Rhododendrons that will survive.The Rhododendrons do not like extreme hot summers. Even worse with no rain.We have podzolic soil and is not that good for Rhododendrons. We can be to hot for some Rhododendrons.I like the palm even though its not as hardy as some Rhododendrons.It will not survive without protection in zone 5 & 6. some Rhododendrons don't need protection for my zone.

- Wes North Van
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Donny
Thanks!
All of my rhodos are by my palms. The first pic shows my largest rhodo which is 10' tall.
When I planted the palm beside it 12 years ago, the rhodo dwarfed the palm. Now the palm dwarfs the rhodo.
I plant rhodos and azaleas by the trachies because they like the same kind of soil, acidic.
I'll take some more pics when they are in bloom which should be any day now.
All of my rhodos are by my palms. The first pic shows my largest rhodo which is 10' tall.
When I planted the palm beside it 12 years ago, the rhodo dwarfed the palm. Now the palm dwarfs the rhodo.
I plant rhodos and azaleas by the trachies because they like the same kind of soil, acidic.
I'll take some more pics when they are in bloom which should be any day now.
Wes North Vancouver Zone 8b/9a
Keats Island BC Zone 8a
Palm Springs CA Zone 9b/10a
Keats Island BC Zone 8a
Palm Springs CA Zone 9b/10a
I've done some internet research on Rhodos and found a couple of Rhodo varieties that may be tall, hardy and evergreen. I am looking to replace a suckering lilac in the back yard that my wife loves.
Has anyone had any experience with the following;
R. maximum or R. maximum roseum---Supposed to be Zone 3b, Evergreen and up to 15' tall(read 10' in Alberta) Sun to Pt shade
R. catawbiense variious cultivars white through red--- supposed to be Zone 4a, Evergreen and up to 10' tall Pt shade to shade
The Rhodos would be great replacements if they are 10' tall and evergreen.
Allen
Has anyone had any experience with the following;
R. maximum or R. maximum roseum---Supposed to be Zone 3b, Evergreen and up to 15' tall(read 10' in Alberta) Sun to Pt shade
R. catawbiense variious cultivars white through red--- supposed to be Zone 4a, Evergreen and up to 10' tall Pt shade to shade
The Rhodos would be great replacements if they are 10' tall and evergreen.
Allen
You don't have to be crazy to grow palms in Alberta..... But it helps
-
- Sprout
- Posts: 72
- Joined: Sat Nov 19, 2005 3:33 pm
- Location: Boise, Idaho, USA (zone 6b-7a)
Rhododendron roseum
Rhododendron roseum from what I have heard is one of the hardiest Rhododendrons on the planet. There may be even hardier cultivars of it. Here in much warmer and much more southerly Boise, it seems to do ok in partial sun; up there in Edmonton the low sun angle should make a sunny spot just fine. It will definitely need watered in before it gets too cold. Does Edmonton get the Chinook winds like Calgary and points south do? If so give them some water during then, if not throw some snow at their bases. Cold weather will dry rhododendrons out esp. if planted under an eave where they cannot get the rain and snow; I have also heard snow will insulate plants, to an extent. I don't think they will get ten feet tall that far north though...
Who wouldn't want free pie and chips?
Thanks Desert Dave.
We don't get the chinooks that Calgary does as we are too far from the mountains. But over the last few years the jet stream has been getting farther north for most of the winter. Now instead of -30 C for 3 to 4 weeks after xmas with 1-2' of snow cover, we get -30 on 1 or 2 days in late November or mid January with no snow. Instead of consistent temperatures below freezing from mid December to early February with snow cover, we now get erratic temperatures between +10 C and -15 C and almost no snow cover.
Last winter the ground dried out so bad that it had cracks up to 18" deep. The garden hose would not fully thaw out, so I packed water at least once a week from the house to the important parts of the yard.
Allen
We don't get the chinooks that Calgary does as we are too far from the mountains. But over the last few years the jet stream has been getting farther north for most of the winter. Now instead of -30 C for 3 to 4 weeks after xmas with 1-2' of snow cover, we get -30 on 1 or 2 days in late November or mid January with no snow. Instead of consistent temperatures below freezing from mid December to early February with snow cover, we now get erratic temperatures between +10 C and -15 C and almost no snow cover.
Last winter the ground dried out so bad that it had cracks up to 18" deep. The garden hose would not fully thaw out, so I packed water at least once a week from the house to the important parts of the yard.
Allen
You don't have to be crazy to grow palms in Alberta..... But it helps
I got three rhododendrons locally. All of them hardy in Zone 3b and 4a and are evergreen.
[/img]
This is the Peter Tigerstedt. It is supposed to grow to 7 feet, flower early May - white blooms with a brown/red splotch.

This is the Hellikki. It is supposed to grow to 5 feet. The flowers are red and bloom in mid May.

This is the Haaga. It is supposed to grow to 6 feet. The flowers are pink with dark pink splotches and bloom early June.
Now I need to rip out a dead tree and the Lilac bush to make room for them.
Allen
[/img]

This is the Peter Tigerstedt. It is supposed to grow to 7 feet, flower early May - white blooms with a brown/red splotch.

This is the Hellikki. It is supposed to grow to 5 feet. The flowers are red and bloom in mid May.

This is the Haaga. It is supposed to grow to 6 feet. The flowers are pink with dark pink splotches and bloom early June.
Now I need to rip out a dead tree and the Lilac bush to make room for them.
Allen
Last edited by Alchris on Tue May 02, 2006 9:49 am, edited 1 time in total.
You don't have to be crazy to grow palms in Alberta..... But it helps
- Jay-Admin
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I usually use photoshop but here's an easy way of doing it. Go to this site. http://www.resize2mail.com
Regards,
Jay
Regards,
Jay
- Wes North Van
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Azalea pic
This one of my favourite azaleas I have.


Wes North Vancouver Zone 8b/9a
Keats Island BC Zone 8a
Palm Springs CA Zone 9b/10a
Keats Island BC Zone 8a
Palm Springs CA Zone 9b/10a