Deciduous Azalea Techniques

[coltranem]

Repot didn't hurt the flowering anyway. Many blooms yet to come then cutting back the long ones again.

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Nice @Underdog I finally got mine to flower but it sort of meant doing nothing all last year and letting it grow.

 

[Underdog]

Nice @Underdog I finally got mine to flower but it sort of meant doing nothing all last year and letting it grow.

Yea, I am still confused about what makes these things tick. If you read back in this thread you see I was convinced it had to be year old wood but this year I had some flower buds set on both old and new growth. When these are spent I'm cutting back pretty hard on the long nodes and leaving the shorts. shrug...
Yours has a nice trunk.
@Leo in N E Illinois and @osoyoung what is the secret?

 

[coltranem]

So I have been thinking you need to prune very early and then leave it a lone to get flowers. I am thinking of concentrating the next few years on developing ramification through frequent pruning and pinching. Once ramfied better I am hoping that I can let it run and get flowers but that new growth won't be so leggy due to ramification.

 

[Leo in N E Illinois]

I earned the hard way, the deciduous azalea need to be at least heeled in, pot buried, to winter successfully here. Just set on the ground is not enough protection. Lost a couple that way. Also learned that it is important to repot before growth gets under way in spring. Late repotting results in death. This applies to deciduous azalea and to Satsuki azalea. Lost a couple this way. So this year, I missed and yet again the repotting window. Below is my only remaining deciduous azalea in the nursery pot I bought it from the nursery in.

Its still alive, healthy and blooming, but basically I haven't done anything. I find I am an "azalea master" only in that I have mastered the many ways to kill them. but I do know why each one died. Its not really funny. I will try in the future to do right by this one. I have got to remember to get into the well house before it is time to move things out and start repotting. It really needs to go into a better mix. All Kanuma next year.

Deciduous azalea 'Soft Shimmer'



'Soft Shimmer'

 

[Leo in N E Illinois]

I'm thinking about a hard pruning after blooms. Then repot next spring.

 

[Leo in N E Illinois]

Ended up pruning back, but kept a pair of leaves on each branch. I feel the whole thing was too weak to risk cutting back to a leafless state.

 

[Kullas]

All of mine is getting a repot into my kanuma mix. It makes it so much more manageable in watering. I have one in kanuma and I love it.

 

[FinnLakk]

Thought I'd share my two collections here. I have nothing of note to add as of yet but excited to learn and develop these.

They have both come from the same mother plant and are natural ground layerings. The mother is a behemoth that I'm looking forward to digging in a few seasons
Flowers on mother plant:
Past their best there but hopefully someone can identify?

 

[Underdog]

This one was repotted early April before flowering, which it did well. I cut off all the long internode spring growth and the current growth is much tighter. Buds setting now which may be a second flush? or flower buds?

 

[FreshAirSunshine]

I am interested in native azaleas as well and am growing two (Weston’s Lemon Drop and Golden Lights) and was in the process of putting together a post in the 5-year-native-plant contest when I decided to make this write-up. If people think it's not appropriate I can deleted it or if it’d be worth a separate thread/post feel free to make one on it. Just figured the time I spent finding this info may be useful to others who are new to these plants like myself.


I did a bit of literature review for deciduous azaleas (with some overlap of general rhododendrons in the US and evergreens when unavoidable) since most bonsai-specific sources don’t touch them. I’m sure there are many people on here who have already looked into this but what the hey – I haven’t found a centralized source for lit review so some other newbie may not either.


My lit review was focused on trying to learn their general care but also learn specifically about leaf size management and long internode reduction/increasing lateral branching. Some info there but also just some general info.


General Resources:


The American Rhododendron Society

https://www.rhododendron.org


Journal of the American Rhodedendron Society

https://www.rhododendron.org/journal.htm


Azalean Society of America

https://www.azaleas.org


The Azalean Journal

https://www.azaleas.org/the-azalean/



Specific Resources/Primary Literature on Deciduous Azaleas:



Overwintering



“Cold Hardiness of Floral Buds of Deciduous Azaleas: Dehardening, Rehardening, and Endodormancy in Late Winter”- https://journals.ashs.org/jashs/view/journals/jashs/132/1/article-p73.xml



“Effect of Fall Fertilization on Freeze Resistance of Deciduous versus Evergreen Azaleas” - https://meridian.allenpress.com/jeh...ct-of-Fall-Fertilization-on-Freeze-Resistance



“Effect of Fall Fertilization on Freeze Hardiness of Deciduous versus Evergreen Azaleas”- https://journals.ashs.org/hortsci/view/journals/hortsci/40/4/article-p1126B.xml



Fertilization



“Nitrogen Availability Alters Mineral Nutrient Uptake and Demand in Container-grown Deciduous and Evergreen Rhododendron” - https://pubag.nal.usda.gov/download/23622/pdf



Use of Chemical Growth Factors



“Micropropogation of azaleas using thidiazuron” - https://www.actahort.org/books/227/227_60.htm



“Thidiazuron: A potent cytokinin for woody plant tissue culture.” - https://www.researchgate.net/public...e_culture_Plant_Cell_Tiss_Org_Cult_33_105-119



“Single Cyclanilide Applications Promote Branching of Woody Ornamentals” – Azalea examples - https://meridian.allenpress.com/jeh...le-Cyclanilide-Applications-Promote-Branching



“CYCLANILIDE INCREASES BRANCHING OF HERBACEOUS PERENNIALS” -https://www.actahort.org/books/886/886_20.htm


Extension of Reports on Cyclanilide (Tiberon) Already Provided

“The Use of Plant Growth Regulators for Branching of Nursery Trees in NY State” - https://rvpadmin.cce.cornell.edu/uploads/doc_158.pdf

“Maxcel Applied Multiple Times is Effective and Safer than Tiberon for Feathering of Apple Nursery Trees in NY State” - https://rvpadmin.cce.cornell.edu/pdf/submission/pdf181_pdf2.pdf


Physical Pruning/Branching


“Growth response of seedlings of flame azalea to manual and chemical pinching” - https://meridian.allenpress.com/jeh...owth-Response-of-Seedlings-of-Flame-Azalea-to


Budbreak/Leafing


“Growth of Rhododendron cultivars as affected by temperature and light” - https://www.tandfonline.com/doi/abs/10.1080/14620316.1998.11511053?journalCode=thsb20


Rooting


“Rooting Response of Deciduous Azaleas, Rhodedendron Section Pentanthera, Stem Cuttings to Mist Regimes and Media Mixes” - https://etd.auburn.edu/bitstream/handle/10415/6460/Thompson, P.G. Thesis.pdf?sequence=2&isAllowed=y


“Rooting and Night-Lighting Trials with Deciduous Azaleas and Dwarf Rhododendrons”

https://ahsgardening.org/wp-content/pdfs/1963-04r.pdf


“STARTING AZALEAS FROM LEAF-BUD CUTTINGS” -

https://scholar.lib.vt.edu/ejournals/JARS/v32n1/v32n1-toivio.htm


“Lazy Propagation” - https://scholar.lib.vt.edu/ejournals/JARS/v54n1/v54n1-towe.htm


“Micropropagation of Flame Azalea” -

https://meridian.allenpress.com/jeh/article/6/2/45/80358/Micropropagation-of-Flame-Azalea


“Energy Conservation in Rooting Deciduous Azaleas” - https://scholar.lib.vt.edu/ejournals/JARS/v38n1/v38n1-cummins.html


“Pruning For Bushy Growth”

https://scholar.lib.vt.edu/ejournals/JARS/v41n3/v41n3-delp.html


Environmental Conditions


“Factors affecting simultaneous reproductive and vegetative budbreak in Rhododendron subg. Hymenanthes” - https://conservancy.umn.edu/handle/11299/113990


Interesting Reads


“The Weston Hybrids”

https://www.rhododendron.org/v53n4p195.htm


“In Search of a Yellow Evergreen Azalea” - https://scholar.lib.vt.edu/ejournals/JARS/v42n2/v42n2-badger.htm


“Magic on the Mountain: An Azalea Heaven on Gregory Bald” - https://scholar.lib.vt.edu/ejournals/JARS/v50n2/v50n2-mclellan.html

 

[shinmai]

Thank you for sharing! Lots of useful material. Well done.

 

[FreshAirSunshine]

Does anyone have specific tips for getting deciduous azaleas ready to overwinter? I know it’s time to stop fertilizing if we haven’t already but I’m not sure the extent to dial back on water or if there’s other things I should do. I do have a cold frame ready and insulation/fleece for the trees but I’m also not sure when to wait till before moving trees into them - after first frost? Before? The trees are cold hardy - northern lights, girards Cathy, Westons lemon drop.

 

[Underdog]

My Gibraltar will sit right here until consistently below freezing. Then under the bench in mulch on the north foundation. More worried about the pot surviving than the tree.

 

[Leo in N E Illinois]

Does anyone have specific tips for getting deciduous azaleas ready to overwinter? I know it’s time to stop fertilizing if we haven’t already but I’m not sure the extent to dial back on water or if there’s other things I should do. I do have a cold frame ready and insulation/fleece for the trees but I’m also not sure when to wait till before moving trees into them - after first frost? Before? The trees are cold hardy - northern lights, girards Cathy, Westons lemon drop.

Do not withhold water, dry an azalea out, they are toast. They will use less water in autumn, use your finger (more accurate than any meter) to check soil moisture. Keep moist, but not saturated. In the Midwest, we have not had much rain, if you get multi day rain episodes, maybe put the azalea out of the rain once it is saturated.

I would not move it to the cold frame until the ground freezes, at least freezes a little. Put too early in cold frame and voles, mice, ground squirrels and other bark eating varmints will move in and nest around the trees. They will eat bark over winter, killing your favorite trees. Always wait until after ground .has frozen and varmints have already found their winter shelter.

 

[shinmai]

Disagree about stopping fertilizer. I’m also in 5b. In September I switched to 0-10-10 in a liquid concentrate, one tablespoon per gallon. I’ll be doing that every two weeks until temps go below 30. [This is for all my deciduous trees, not just azaleas.] Leo is absolutely right about not letting them dry out. My trees go into a small greenhouse that’s heated to 37 degrees, and in winter I water lightly about once a week or so.

 

[FreshAirSunshine]

Thanks for the input. Mice etc aren’t a concern for me - the cold frame won’t be accessible to any critters (unless they can fly). Good to know about the water - I’ve been keeping them reasonably watered and protecting from drying out but wasn’t sure if I should - it just felt correct. I had been doing the finger and chopstick water tests and just adjusting the watering frequency to match the drying rate as the humidity changes. Wasn’t sure on fertilizer but sounds like you’ve had no trouble in my zone @shinmai. I don’t have any zero nitrogen stuff right now though.

 

[shinmai]

https://www.amazon.com/dp/B097RXBVZL?psc=1&ref=ppx_yo2ov_dt_b_product_details

 

[Bonsaipadawan]

Hello everyone I wanted to make an update on my azalea that I had posted some questions about almost exactly a year ago. So last winter I had it arrive from Florida to NYC and I believe that shocked the plant to drop all of its foliage maybe in transit.
I kept close attention in it this winter and it didn't experience as much leaf drop as some of my satsukis did. I find this curious not sure what you all will think. I did a repot a year ago where I used bonsai soil but I didn't know at the time Kanuma is what some say is better. I did tease the roots a little today and added some organic mix, mixed with kanuma into a larger cloth grow bag. I am going to enclose some photos of it this past summer and from today pre repot. I wasn't very invasive with the roots.

I am thinking up potting it will put more vigor into the tree. Do you all think my next steps should be. Should I be considering chopping some of the larger straighter branches?

It was a lot of fun to see it explode with growth, going from no foliage to a whole lot.
I also included a flower from the plant.

I remember the seller told me it's girards crimson but a member here assured me they do not believe it is I am hoping the flower might help to identify it but I think that might be difficult as there are thousands of azalea varieties out there. I appreciate all the help you all have given me thus far and felt like I could use a little advice but also update the thread on the azaleas first year with me and what I've seen and observed.

 

[FreshAirSunshine]

@Bonsaipadawan glad to see it recovered! While not a Japanese azalea, the Girards azaleas are evergreen, not deciduous, so I’m not sure if it really fits the theme of this thread. I have a Girards Kathy White which I hope perks up like yours - mines looking a little sad right now but honestly looked a little sad at purchase as well so….

 

[FreshAirSunshine]

@Bonsaipadawan glad to see it recovered! While not a Japanese azalea, the Girards azaleas are evergreen, not deciduous, so I’m not sure if it really fits the theme of this thread. I have a Girards Kathy White which I hope perks up like yours - mines looking a little sad right now but honestly looked a little sad at purchase as well so….

I see I was not properly addressing the debate you had last year. If it didn’t experience as much lead loss as your satsuki then it sounds like an evergreen to me but obviously that’s been surprisingly hard to pin down in your case. I say that knowing with the weird weather my Northern Lights deciduous azalea only recently finally dropped all its leaves.