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New to Azaleas, Help for a tropical climate

Posted by Ebonhawke none (My Page) on
Thu, Feb 9, 12 at 8:56

Hi! I'm new to the forums but I have been reading a lot of posts about various techniques and such from such a helpful community so I work up my courage to ask some questions:

I live in the Philippines with a tropical climate. I recently bought a Japanese azalea with bright and vivid pink flowers and small leaves. I bought the smaller version since it is cheaper but the nursery has the mother plant on display and it is a about 5 1/2 feet tall. I washed off all of the soil around the roots when I got home and saw some vine weevil grubs inside, I am pretty sure I removed them all and managed to catch the 2 adult weevils while I was transplanting. I prepared a 26 inches diameter plastic pot about 20 inches tall and put on a neutral potting mix I bought from the same place. The mix is very well draining when I water it, it took less than a minute for the water to flow out beneath the pot. My tap water is alkaline with a ph of about 7.5 so I mix in some vinegar when I water it. At about a week since transplanting, some leaves exhibit brown tips and some got black spots which rapidly made the leaves turn yellow and fall off, as I near the 2nd week, the black spots became fewer and yellowing is almost gone, I got new shoots from everywhere but the problem is all the flower buds that existed turned brown and some fell off, is it normal or does it have something to do with the temperature where I live in, my garden is on a rooftop 5 storey building so most crawling pests won't reach my plants. I have 14 feet high walls all around so sun is also no problem, since I have a tropical climate, I have 32 degrees celsius daytime temp and about 27 degrees celsius nighttime temp. Very high humidity here so I use a drip system now to water it. I mulch with coffee grounds and put some slow release 14-14-14 fertilizer pellets to help with acidity, also thinking of buying some ammonium phosphate since I'm thinking of buying more azaleas if my prognosis is good. Is it normal to not get flowers in the first season? Or should I think of getting other kinds of plants and not azaleas. I'm sorry for the very lengthy post and I hope you guys can help me. Oh for added info, I also have Indian Ixora, Gomphrena Globosa, Agapanthus, Iris Pseudacorus and Fuchsia Plants in the garden. Can I raise azaleas in my area of should I forget about it?

I can provide pictures if you guys want to get a better idea of what environment I can work with.


Follow-Up Postings:

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RE: New to Azaleas, Help for a tropical climate

Your alkaline water is a real problem. It is best to collect rain water since it is usually acidic. To acidify the soil, use powdered sulfur. It is slow to take affect but is very long lasting. Details are on my website which I post below.

Perfect plants for your climate are the Vireya Rhododendrons native to your area and down toward Indonesia. They are grown exactly like orchids. They will usually bloom a couple times during the year. My website has information on Vireyas also.

There are some challenges to raising a temperate azalea in a tropical climate. One of the greatest challenges is disease. Some azaleas are resistant to disease and do better in warm climates. They include:

Flame Creeper - Late, Dwarf. Noted for its tolerance of full sun, this reliable azalea displays a profusion of scarlet-orange flowers. It makes a good ground cover with its small leaves and creeping habit.

Hino Crimson - Early, Low/Med height. Bright crimson flowers unfold in April, and holding their color well. This attribute, coupled with sun tolerance and red winter foliage, makes Hino Crimson an excellent all around choice. Planted in the open, it grows to a dense 2.5' mound, although it adapts well for use as hedging.

Hinode-giri - Early, Medium height. One of the more sun-tolerant hybrids, this azalea produces multitudes of rose-crimson flowers early to mid-season. Small, glossy leaves turn bright red in winter on this dense plant.

Stewartstonian - Early, Medium height. A sun tolerant hybrid, Stewartstonian displays lush red 2" blooms that, in the light, appear blood orange. Winter foliage deepens to wine red, making it an excellent winter foliage plant.

Here is a link that might be useful: How to grow rhododendrons and azaleas.


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RE: New to Azaleas, Help for a tropical climate

Wow! Thank you for pointing me in the right direction. Looking at the Vireya pictures, I think I saw one right after I bought my Rhododendron obtusum. It has glossy leathery leaves and seems very very healthy, maybe because it is native to my country. It has dark red flowers on it borne in clusters of about 6-8 on branch ends. I will head back to the nursery on the weekend to look around.

Your site is very very informative. I can't thank you enough for the help.


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RE: New to Azaleas, Help for a tropical climate

  • Posted by bboy USDA 8 Sunset 5 WA (My Page) on
    Fri, Feb 10, 12 at 16:41

I'd think hot climate azaleas belonging to groups with names like Indian and Belgian Indica etc. that have been long grown for forcing in greenhouses or displayed to great effect on large properties in the Deep South of the US would be better than the Kurume etc. types listed above. Kinds like that are what are seen in Hawaii, for instance. These are derived from species native to lower altitudes and hotter situations (and their hybrids).


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RE: New to Azaleas, Help for a tropical climate

Update on my Kurume: Lots of new shoots and leaves...Found out that the one chewing on the leaves are sawfly caterpillars. Found about 5 dead on the coffee ground mulch I just put in. Still have issues with black spot fungus and browning leaf tips but aside from that it is not wilting or anything. I am heading out to the plant nursery tomorrow to find some other hybrids and Vireyas. I don't know but I find the Kurume form a bit more exquisite even when not in bloom than the Vireyas. I hope I find some hybrid of the two or the hyperthicum(sp?) one if I'm lucky.

Also I read that some rhododendrons have double flowers are they worth it? I had bad experience with double flower hibiscus rosa sinensis the flowers are too heavy and bend the plant or fall off. Is it not the case with Azaleas and Rhododendrons?


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RE: New to Azaleas, Help for a tropical climate

  • Posted by bboy USDA 8 Sunset 5 WA (My Page) on
    Sat, Feb 11, 12 at 12:11

The Vireya (and their garden hybrids) are a whole large section of the genus with a great variety of flower and plant forms. If you have seen one you have most definitely not seen them all.

Flowers of certain double evergreen azaleas may bend down when soaked. Otherwise I have not seen a problem with double azalea (and rhododendron) flowers being too heavy for their stems.


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RE: New to Azaleas, Help for a tropical climate

Just got back from the plant nursery. The kind lady there told me a lot of things about them.

1. If I buy Vireyas, they won't flower because of the altitude since I live in Manila which is considered low lands. They will only flower in high altitudes like Baguio in here.

2. The azaleas they are selling are hybrids from Rhododendron Hyperythrum. She assured me that they will survive our hot summers if I can provide the shade they need.

3. She is selling both Vireyas and Kurume x Hyperythrum hybrids and she assured me I will have more flowering success with the Kurume x Hyperythrum hybrids.

4. She also offered to sell me Camellias, I may need to look at it since she claims they will provide good shade for my azaleas and have the same exact living conditions as them so good companions, is that true?

I'm so excited, I already placed an order for 5 double white with yellow centers, 4 double mauve/lavender spotted ones and 5 double whites with pink borders azaleas, they are so gorgeous. ^^


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RE: New to Azaleas, Help for a tropical climate

  • Posted by bboy USDA 8 Sunset 5 WA (My Page) on
    Mon, Feb 13, 12 at 13:19

There are various different species of Vireya that grow from lowlands to mountain tops in the wild. Again it sounds like characteristics of part of the group are being wrongly attributed to the whole group. Here suitable kinds are even grown by enthusiasts as house plants. You should look into the subject more before accepting that none of them will work for you.

Rhododendron hyperythrum is not an azalea. If somebody has produced hybrids between this and azaleas then these hybrids will be azaleodendrons and not azaleas. Such crosses are not impossible, per se, as a small number of other kinds are already known, but it is certainly not usual - I would want to check to see if R. hyperythrum was in fact the species involved.


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RE: New to Azaleas, Help for a tropical climate

Thanks bboy. I purchased 1 Vireya to try them out, might as well grow them at the same time. ^^ Also are kurume hybrids fast growers? I read somewhere they are slow but I just transplanted one as a trial specimen 3 weeks back and the new shoots are already 1 1/2 inches to 2 inches long should I be alarmed? My coffee ground mulch had these white powdery stuff on them so I removed them seems like a fungal growth. Looking for peat moss as substitute mulch, are they good?

I will certainly heed your advice on the altitude thing. I need to educate myself more on the subject before taking somebody's word for it.

Summer will hit us here in 1 month time, I will find out if all of them will die. I certainly hope not! ^^


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RE: New to Azaleas, Help for a tropical climate

Do not use peat moss as a mulch. It is a soil amendment to be used when preparing the soil in a bed or container and can cause severe problems when used as a mulch including dehydrating the soil and preventing moisture from reaching the soil. It also tends to blow around. It is best to mulch with a 2-inch layer of an airy organic material such as wood chips, ground bark, pine needles, pine bark or rotted oak leaves. A year-round organic mulch will also provide natural nutrients and will help keep the soil cool and moist.


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RE: New to Azaleas, Help for a tropical climate

Do not use peat moss as a mulch. It is a soil amendment to be used when preparing the soil in a bed or container and can cause severe problems when used as a mulch including dehydrating the soil and preventing moisture from reaching the soil. It also tends to blow around. It is best to mulch with a 2-inch layer of an airy organic material such as wood chips, ground bark, pine needles, pine bark or rotted oak leaves. A year-round organic mulch will also provide natural nutrients and will help keep the soil cool and moist.


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RE: New to Azaleas, Help for a tropical climate

Aaah okie....noted. I took pictures of the specimen I bought and had it ID'd in a different forum. The results just came, it is not Kurume hybrid but Rhododendron Kanehirai Wilson, sheesh plant nurseries will tell you anything just to make money.

Kinda relieved since it exists in subtropical Taiwan but I wonder if it will survive here though, not much is written about it in the web save some pictures.

If I can't get my hands on pine bark or needles mulch can I use wood chips? I read somewhere it makes the ph go up. Lots of wood chips here and they look clean too. We don't have oak here so that is out of the question. I found a bag of acidifying agent in a DIY store used for swimming pools to neutralize chlorine can I use that to lower ph?

I'm really grateful you guys taking the time to teach an obvious beginner such as myself. Thank you!


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RE: New to Azaleas, Help for a tropical climate

For acidic plants, conifer bark chips (pine, fir, spruce, cedar, juniper, etc.) are the ideal mulch. The wood is not, but can be used if you monitor the acidity of the soil. The main thing to look for is to watch the leaves of rhododendron and azalea plants. If they turn yellow or yellowish with green veins, the plant has chlorosis which is usually a lack of iron caused by soil that is not acidic enough.

I doubt the pool chemical is acceptable. They are usually soluble chemicals like muriatic acid and will not have a lasting effect on the soil. The best approach is to use peat moss in the soil mix when planting and then to add powdered sulfur to the soil if there are problems and you need to increase the acidity (lower the pH). Powdered sulfur (flowers of sulfur) is available from some garden centers, but it is also in most pharmacies. The same product is used in gardens and as a medicine. The amount to use is discussed on my website.

Do not use aluminum sulfate. It is sold in garden centers to lower pH, but the aluminum ions accumulate in the soil and are toxic to rhododendrons and azaleas.

Here is a link that might be useful: How to grow rhododendrons and azaleas.


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RE: New to Azaleas, Help for a tropical climate

Aaah I will try the powder sulfur. Can I just add it onto the surface or should I dig it in? I don't want to risk disturbing the roots so I'm kinda skeptical about the digging part. Right now I'm adding vinegar to my diluted liquid fertilizer once a week at half strength so far no chlorosis yet, the plant does look healthy. I avoid splashing water on the leaves since it is so humid here so I use a drip system directly on the crown, so far so good.


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RE: New to Azaleas, Help for a tropical climate

  • Posted by bboy USDA 8 Sunset 5 WA (My Page) on
    Fri, Feb 17, 12 at 20:47

If you are able to know the pH of your tap water maybe you have a way to monitor the pH of your soil also. Especially if trying to change it you should be keeping track of the effects of any additives. Proceed carefully, even one pH point in increase or decrease represents a huge change that can have adverse effects on soil life if undertaken rapidly.


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RE: New to Azaleas, Help for a tropical climate

Interesting thread.
Some pool pH lowering products contain sodium bisulfate, which would add very undesirable sodium to the soil. Rhodyman's advice to use sulfur is best.
The report of R. Hyperythrum based azaleadendrons is utterly fascinating...though probably incorrect. If you can get some pictures of such plants this spring they would be appreciated.


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RE: New to Azaleas, Help for a tropical climate

hi @ebonhawke, i'm in the philippines too and saw some azaleas in baguio orchidarium last weekend. beautiful almost-neon blooms. i just didn't buy any because i didn't know if they would survive the weather where i live. how did yours do? did they survive? or should i just forget about getting azaleas?


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RE: New to Azaleas, Help for a tropical climate

Most of the ones with almost-neon blooms are Vireya Rhododendrons which are tropical. They will not tolerate a freeze. Some Vireyas are from Borneo and the Philippines. Their culture is very much like that of orchids. Some are terrestrial, but most are epiphytic.

Here is a link that might be useful: Vireya Rhododenrons


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RE: New to Azaleas, Help for a tropical climate

Most of the ones with almost-neon blooms are Vireya Rhododendrons which are tropical. They will not tolerate a freeze. Some Vireyas are from Borneo and the Philippines. Their culture is very much like that of orchids. Some are terrestrial, but most are epiphytic.

Here is a link that might be useful: Vireya Rhododenrons


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RE: New to Azaleas, Help for a tropical climate

thanks for the helpful tip, @rhydyman! i will certainly research more on vireya rhododenrons. going back to that nursery next month. i might give it a try! :)


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