Question
QUESTION: Hi Wayne,

Although I don't expect you to remember my previous questions I sent earlier this year. I have dendrobium (evergreen/tropical type) and an oncidium (some hybrid within that alliance).

The den I purchased last year in Sept while in flower. I followed your instructions when it was in growth. Now the growth has stopped and I can see a little bud in the center of the new growth at the top of the cane which should become a spike, but it hasn't. I've given it TONES of light and water, but nothing is happening. The new growth is also a little shorter and thicker than the previous growth. Has it entered into another dormant stage? How can I get it to send out a flower spike?

The Oncidium hybrid I also purchased in bloom around July. It bloomed for about a month, then after all the flowers faded I cut the stem from the base, but the pseudo bulbs have all gotten wrinkly. The leaves are all still green and stiff, and I can see signs of new growth, but I'm wondering how I can make the pseudo bulbs plump again?
Also, How I can get it to send up a new flower spike?

I'm looking forward to hearing your expert advice!

-Theo

ANSWER: With the dendrobium, you need to reduce the watering to a bare minimum (maybe only misting).  It often takes a couple of months for flower spike growth to commence.  I realize that it was in flower last September, but you are growing under different conditions than under which it was grown to produce that flowering. A trick many growers use to induce flowering is to stress the plant. This is often done by reducng or eliminating watering.  It sounds like you have a healthy new cane that can withstand this stress since it is plump and can provide the needed sustenance.  Other than that, a large dose of patience will be required.  Try not to look at it every day.

With regard to the oncidium alliance plant, it is normal for pseudobulbs to shrink during the rest period when little or no water is provided.  That happens in nature during the seasonal dry period where these types of plants grow naturally.  When the rains come (ie when you resume watering and feeding) the bulbs will firm up again (especially the newest bulbs that should have good root growth).  The start of new growth is also the time for repotting.  You will need fresh potting mix to be able to water sufficiently well and avoid root rot.  Flowering comes when the new growth matures and forms large pseudobulbs.

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QUESTION: Hi Wayne,

Thanks for the reply!

The den is a mini version. It has 6 leaves and two lower small ones yellowed and fell off since it has ceased growing in mid August. But I have been watering it a lot. I live in NY and it was outside all summer until early autumn. We had a particularly hot summer this year. I'm going to try and give it less water, or just spray it every few days and see what happens.

The last flower on my oncidium fell off in early August. I've been watering it regularly once per week and fertilizing it lightly. I purchased a new concentrated fertilizer (that I mix with water) that has more phosphorous which I read encourages blooms. After I started using the fertilizer I noticed some new growth. The new growth that existed when I purchased the plant in July is beginning to mature with a small, plump pseudo bulb. Unfortunately, there aren't much roots under that pseudo bulb so I'm keeping it in place with extra bark chunks.

Should I be watering the oncidium (along with another phal that's now budding) more often since there's new growth and the bark medium dries out quicker?

-Theo

ANSWER: Thanks Theo.  Don't be surprised if the dendrobium losses all of its leaves. That is normal.  Some of these types even flower on leafless canes. Try to keep it on the drier side.  These plants tend to see wet conditions as the start of the rainy season and send up new growth. If you visualize these plants as they respond in their natural environment, flowering occurs at the end of the growth cycle when the dry season sets in.  They then flower, get pollinated and grow their seed pods over the dry period and those seeds disperse with the onset of the rainy season when they have the best opportunity to grow. The same could be said for any plant with water storage organs (ie pseudobulbs)

It sounds aa if you should repot the oncidium alliance plant.  This is generally recommended following each flowewring.  The old potting mix is probably broken down and holds too much water.  While inserting extra bark chunks may help some, it really needs complete replacement of the old potting mix with a fresh  medium size orchid potting mix.  It is likely that your maturing growth is small because the potting mix has led to deteriorating root condtions.  Be sure to use use a pot with lots of drainage holes for repotting and be sure to wet the new potting mix thoroughly before use.  With fresh potting mix you may be able to water and feed more freely without the fear of root rot.

I would avoid repotting when a plant is in flower or bud, but when it has finished flowering, that is the time to repot.

It is important to choose the right kind of orchid potting mix.  If the fir bark pieces in the mix are too small, too little air enters the mix and it stays wet longer.  Large pieces of fir bark tend to take longer to wet and the mix may dry too fast.  You want a potting mix that has the average fir bark size about 1/2 - 3/4".  And, of course, it is important to have a mix that contains other ingredients such as charcoal, perlite, etc.  Each of these has an important function in holding some moisture and/or keeping the potting mix open, even when the organic parts of the mix start breaking down.  If the mix you buy has some smaller ingredient such as dust, you should screen those out before using it.  Dust just clogs the air spaces in the new potting mix.

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QUESTION: Wayne,

Thanks again for that advice!!!

The den (mini-dendrobium phalaenopsis) does seem to have water stored inside the canes, but only one of them has leaves on it. However, just to be clear, this is NOT the deciduous kind, it's the EVERGREEN TROPICAL kind that has flowers coming from one spike at the top of the cane. BUT if you had that in mind when you sent the last message, then I should just leave it alone right? Does it need more light than my oncidium and phal? Should I still keep it over a humidity tray?

I repotted my oncidium after all the blooms faded in August, but yesterday I saw it had lots of rotting roots which I cut off along with the dead stub it was connected to and repotted it again using the exact same potting mix you described. The maturing growth I mentioned had no roots left, which is odd since the plant seems healthy.

How can I encourage root growth in oncidiums?

I have a mini-phal that is doing very well. I have some experience with them I hear they're the easiest to care for. It has some buds on it's new spike that sprouted off the old spike. I want promote as many blooms as I can with deeper colors. I hope the high-phosphorous fertilizer will do the trick.  

Answer
I think you should provide minimal care to the mini-dendrobium until it shows signs of new growth.  Use of a humidity tray is a good idea. You can also mist it lightly a couple of times a week.

With regard to the oncidium alliance plant, it is not unusual to experience root rot as a result of either poor potting mix or over watering.  You could insert a finger a couple of inches ito the potting mix.  If it feels damp, withhold watering.  The potting mix may look or feel dry on the surface but be wet at mid or lower level.

Both high phosphorous and higher light levels can produce brighter flowers.  I don't know that miniphals are necessarily easier to grow.  It depends upon which species are involved in the hybrid.  Some of the miniature species are difficult to grow, but when used to create miniature hybrids, some of the difficulty involved in growing them is improved.