Re: Dendrobium spectabile - Alien Orchid

[dennis westler]

Dear Mark:

There are a few reasons i can think of for this plant not blooming. It does want more light than a Phalaenopsis prefers, but not much so it might just be a matter of adjusting the blinds, or keeping it out in dappled shade through spring-fall. Second, it is a hot grower and wants to have really warm days through the growing season. Phalaenopsis are as well,but years of breeding as houseplants have made them more adaptable. Finally  they have a much more pronounced seasonal cycle than the Phalaenopsis do in terms of moisture. They will want to be watered while still moist when in active growth, and fed regularly. but when that growth is complete in the late summer-fall, they will want to go dry between watering, and will not need to be fed. You can step up the water when either buds appear or new growth commences. 

Often with plants like this it is the provision of these seasonal cues that initiate bloom. 

Keep in mind that this is a really large plant that is very unlikely to bloom until it is at least 18" tall, and perhaps not until it is 24". They are quite spectacular  but often too large for growing in the home.

You may find that lights will help, but I would still keep the winter dormancy (less water, no food, somewhat cooler nights) in mind. You want around 2000 foot candles for this plant, which you may already have. 

Sincerely,

Dennis

[ist...@gmail.com]

How long it takes to grow such a big plant?

[dennis westler]

A plant like this, that gets tall with maturity should begin to flower when it is at least a foot tall. How long it takes to reach full size will depend on your conditions and care. From seed to full size can take some plants at least 10 years. If your plant is 12"-18" tall at this point and showing no signs of flowering, try increasing light, making sure the difference between day and night temperature is between 5-10 degrees f, and allow the plant to get dryer between waterings in the winter than you do in the summer. Perhaps allow the bulbs to get somewhat ridged between watering in the winter if the plant is not actively growing, rather than being plump and full all the time. These daily and seasonal changes in conditions can encourage blooming, while consistancy does not, with some species.

 

Sincerely,

Dennis