Den. spectabile - culture & blooming
 

Den. spectabile is a fairly robust plant & vigorous grower. Blooming habits can vary greatly, depending on culture & conditions. This species (like most of the New Guinea, latouria type dens & their hybrids) is very tolerant of a wide range of light, temperature & moisture conditions. However, there is a difference between tolerance & preference, between surviving & thriving.

Den. spectabile is a vigorous grower. Under the “wrong” conditions, this plant would rather eat than bloom. Under warm growing conditions, if you keep feeding, it will keep producing new canes & blooming will be deterred. The normal growth/bloom cycle is: 1) initiation & growth of new canes, beginning in late spring through summer (depending on your climate); 2) maturation & hardening of canes in late summer or early fall; 3) initiation of flower spikes & blooming, in late winter or in spring. So you should, at the very least, stop nitrogen fertilizers in early fall. Blossom boosting fertilizers are not necessary during this period

During this period, under intermediate, or cooler conditions, new vegetative growth should slow in the 60’s & cease when temps get into the 50’s or lower. Fertilizing would be extraneous. Watering is necessary. The maturing of the new canes & pause in new vegetative growth, then, becomes a signal for the plant to initiate blooming. The cooler temps temporarily stop new growth, but they are not what initiate the blooming. In warm conditions, mature canes will also bloom … if the plant is not continuously producing new canes. So stopping the fertilizer in early fall is important.

There are also different sizes for this species. Offspring propagated from plants taken from natural sources tend to become very large before blooming … especially if these offspring are fed heavily & without pause, or with no winter. A very large proportion of Den. spectabile plants in cultivation today probably originated from our nursery. We have produced & sold 10-15 thousand plants, over the past 25 years, throughout the US & to many foreign countries.

Originally, it was not unusual for Den. spectabile plants to reach 24” to 30”, even 36”, before first blooming. Over the past 25 years, using select individual breeding parents, we have been able to diminish the overall height of plants & they have begun blooming as much smaller plants. In the past 10-12 years, we have produced & sold plants that are capable of blooming from 12-14” canes (a few juvenile growths, then 2 6-8” canes, before the bloom growth). Of course, the cultural practices described above are very important to bloom a manageably sized plant, as opposed to a non-blooming large plant.

Really love this species. Thanks for the culture info.

D. spectabile culture.
 

Thank you for all of the culture information you provided. You mentioned selling 10-15 thousand plants. Can you say more about your greenhouses and how I can contact you?
Jeri149

Thanks for the cultural info. I have a Den spectabile seedling, that I purchased from Oak Hill. I hope that it will bloom at a small size. Do you have any recommendations for light levels? My plants are growing in an east-facing window. My Den convolutum, and Den microchip bloom under this light, but I'm not sure it that's enough for spectabile.

Fantastic, and great info!

In which direction do these den-phal types grow their new canes? Typically when I repot I try to push the oldest canes towards the edge so that new growth goes towards the open space.

I repotted my Den. Spectabile earlier this year (it has over a dozen canes, some 2 feet) doing the same thing and now I see 6 new canes growing, but from all directions. Did I misjudge its growth habit?

New roots are just barely emerging, and I have half a mind to repot it again, but in the center. Should I do so?

D. spectabile is not a phalanthe type Dendrobium. It is a
Latouria type. Grows well in light levels similar to Cattleya. Mine grows best in about 90% "lava rock". The remainder coarse bark, clay pot. New growths stay close to the existing canes, but if you notice a general growth direction favor allowing extra room on that side. I water/fertilize as for Cattleyas in summer, a little drier and less or no fertilizer in winter (but not dry like Nobile types).4