Dendrobium xdelicatum, kingianum, questions

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I got two Dendrobium xdelicatum back bulbs from our orchid society speaker in fall 2014. One I potted up here in Phoenix. The other I took to my mother (S Cal just inland from the coastal hills.) Mom's went into a 2" / 5cm square plastic pot with pumice and fallen leaves. We placed it outside on the soil surface of an Epiphyllum hanging basket, with water but minimal fertilizer. It made a new growth spring/summer 2015, equal in size to the back bulb. It stayed outside. When I visited at Christmas 2015 it was starting two flower spikes from the newest growth. It's going on the jacaranda soon along with the Laelia gouldiana 'Greta Garbo.'

The D. xdelicatum I kept here in Phoenix died in the spring heat on a shaded patio, along with a small D. kingianum back bulb. I may try with D. xdelicatum in the future, in the house for the summer.

At our April 2015 show I got a 3-back bulb division of D kingianum 'Roy' from a member of our local society. She said it can take heat. This clone makes larger pseudobulbs than many other clones. It made a strong new growth in spring 2015, but it wilted in the heat when I didn't water it enough. I left it on a shady patio for the summer, where it was exposed to our 110+ F / 43C+ temperatures, but no direct sun. This year's growth matured bent over the rim of the pot, but the same overall length as the back bulbs. In late October I moved it to my sun room, nights not below 60F / 15C and days often into the 80s F / upper 20sC. This plant is making a very vigorous new lead right now, despite my withholding winter water, so I've decided to begin watering and fertilizing it. The 3 back bulbs all bloomed before coming to me. The new growth doesn't have spikes, so I don't think it's going to bloom this year - or might it still?. Should I keep it outside next winter, bringing it inside on the few frosty nights?

I also got a couple of D. kingianum seedlings from Carter & Holmes this summer. On arrival I could see they had been grown as deep shade bog plants, and had no chance outside here. They looked like lush, shiny green ferns, complete with a moss carpet on the shredded cedar. I even had trouble getting them to adapt to living inside the house with 50% humidity. They are still alive, but I don't think I watered them enough, either. Just the newest growths have survived, and they have lost most of their roots. I'm treating them with KelpMax and keeping them evenly moist, but nothing has happened in several months. Do these tend only to root once a year?

Thanks.

[Bud]

I suggest you don't bring your orchids outdoors in your grow zone at all....your atmosphere will suck the moisture out of your orchids....

---------- Post added at 02:33 AM ---------- Previous post was at 02:30 AM ----------

invest in a humidifier with an oscillating fan....so you can grow Vandas in a window with all the bright sunlight you get....

[WhiteRabbit]

Maybe put them outside when temps aren't so brutally hot ? Sept - spring blooming? My kingi, and a few hybrids of it are outside here all year - just sheltered from possible frost or freeze, especially since there are usually spikes by the time we get any. Then inside in a sunny window during the hot summer ?

[AnonYMouse]

I'm growing my kingi in the east window; I/W, ~50% summer/75% winter RH. I grow it in pumice and it does get dry. I don't know if it is optimum but I've bloomed it this way.

[epiphyte78]

Personally, I would focus more on the Dendrobiums that are from Northern Australia such as...

Dendrobium bigibbum
Dendrobium canaliculatum
Dendrobium carronii
Dendrobium discolor

These guys and many of their crosses love the heat. Well... within reason of course. And I can't honestly say for a fact that Phoenix heat counts as "within reason"!

Perhaps it's safer to say that these Dendrobiums need more heat than most xdelicatums, kingianums and speciosums. Although... these three Dendrobiums do have a fairly wide distribution range so some varieties are going to be more heat tolerant than other varieties.

HR Nursery in Hawaii is one of my favorite sources for warmer growing Dendrobium hybrids. Here are a few from their Winter catalog that I'd recommend...

Den. antennatum 4N x discolor
Den. antennatum x capra
Den. antennatum x johannis
Den. Blue Twinkle (canaliculatum cross)
Den. Hawaiian Punch
Den. Minnie (johannis x carronii)
Den. mirbelianum x helix
Den. mirbelianum x johannis v. nigrescens
Den. tangerinum x discolor v. bromfieldii

My personal favorites are canaliculatum crosses. I think the plants themselves look nice even when they aren't in bloom. Here's a photo of the roots from my Den discolor x canaliculatum growing on my Pachypodium lamerei.

[Bud]

its January 20th and its 11am in Phoenix and I checked the weekly weather in your grow zone: in the daytime is in mid 70's and the nights are low 40's....your humidity level is 37% in the day and very low at night....unless your humidity level is a constant 50% and above....then by all means you can bring your Dendrobiums out. Your temps are great for Dendrobiums this time of year for the night do not reach frost levels....but your major problem is the lack of humidity/moisture in your atmosphere.

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Thank you. I know I will have to keep any Dendrobium inside my house for the summer due to both humidity and temperature issues. My main question had to do with how to get kingianum to bloom, since my sunroom where I winter the plants gets pretty warm during the day and is around 60F at night for the sake of my Vandas. I think this is why my D. kingianum 'Roy' is pushing a new lead now rather than flowering.

If my reading is correct it grows in cultivation happily in a lot of places in Australia with fairly low humidity year round. Kingianum has thick leathery leaves, and my experience has been orchids with such leaves don't usually mind lower humidity than they get in habitat. My other evergreen dens are in the sunroom with its higher humidity, except I put the deciduous ones that like a cool and dry winter rest outside next to my door, where they will not freeze, but I will see them all the time.

Knowing that people in southern California leave them out all winter is good information for me. I will do that next winter. The official readings from Phoenix are at the airport, which is in a barren area. I have a garden around my house so it is a lot more humid here. My winter night relative humidity is often in the 30%-40% range and large parts of Los Angeles are like that, too.

---------- Post added at 01:30 PM ---------- Previous post was at 12:59 PM ----------

I found an older thread here with detailed instructions on growing D. kingianum, copied from a yet older article:

http://www.orchidboard.com/community...hen-start.html

The article says night temperatures are the key to good blooming, and says winter night temperatures MUST be below 50F / 10C. (Emphasis on MUST in original.)

[NYCorchidman]

Your plants, especially kingianum can definitely grow outdoor in zone 9.
They actually need this cold winter to thrive and flower well.

If your plant does not have much root and you would like to root them, then just keep them warm inside.
They will go into growing mode once it is warm.

[isurus79]

Kingianum needs cool temps to bloom and mine are doing just fine taking nights below freezing right now. This a a damn tough species. If I were you, I'd pot this lithophytic to terrestrial species in 50/50 mix of sand/peat in a clay pot. The mix should dry at an appropriate rate for your climate (I'm growing my Crytopodiums this way and they love it) with a good mix of moist/dry media.

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Sand/peat! Is it carnivorous?

Back to serious. Is your plant dry when it gets that cold? Do you let it get winter rain?

My D. kingianum 'Roy' is in a 6" clay azalea pot in what was sold as "MiracleGro Coarse Orchid Bark." It isn't a miracle. It isn't coarse. There are a few bark chunks, but it is about 80% small bark chips and sawdust. It was all I could find last April nearby when I got the back bulbs. It is relatively water-retentive but does dry out nicely in a clay pot.