treatment for dormant plants

[fishmom]

I have a variety of catasetinae, both species and hybrids. I am wondering how important both light and temperature are to these plants. I have heard vendors (not Fred Clarke, though) imply that you could put these plants in a closet and they would be fine. In nature, though, they obviously experience the cooling and shortened days of winter and the opposite for spring.

My plants are all in the house now, and most are going dormant. If I look at species culture information, I can guess at winter temperatures, but do I need to worry about cooling to the right temp for each one? Do they still need bright light on the pseudobulbs? I'd love to put them in a corner and forget them, but I am emotionally invested in these babies and I want to get the best growth possible in future years.

Any thoughts?

[estación seca]

In habitat they will be exposed to bright sun on the bare pseudobulbs during the long, dry and - from the perspective of someone living in a cold-winter climate - warm winter.

I strongly suspect they will be photosynthesizing with the pseudobulbs even though leafless and not receiving water. People might get them to survive in a closet, but I wouldn't chance it. They probably don't need your brightest spot but I would make sure they get some light.

[AvantGardner]

I have over-wintered both ways and I find it best to keep sun on them. Prevents rot and pests from running rampant. And I'm OCD about my catasetinae

[Regelian]

Photosynthesis is happening during the Winter, let's not kid ourselves. It does not turn off, as long as there is light and some water available. Humidity in Winter may be high for some Catasetinae, although no rain falls.
Also, good air circulation is still paramont to prevent rot and aid in general respiration of the otherwise dormant plant. Photosynthesis has a dark side, that is the night, when the gas exchange to remove excess O2 and absorb CO2 largely takes place. It is sort of the cleaning crew going through evenings and getting the plant ready for another day of sugar-producing photosynthesis.
The idea of putting them in darkness is simply not understanding what dormancy actually is. It is simply an adaptation to prevailing conditions. Most seasonal dormant plants have recessive genes in their inheritance that would, over generations, allow them to adapt to a wet Winter, should it become the norm. As we know, they would not be the only plants in dormancy in their wild habitat. Host trees may well be naked and in full sun, as well.

On the more practical side of handling dormancy in the greenhouse/ windowsill, I keep watering right up to full leaf fall. Some plants never really go fully dormant, such as pileatum cultivars (Orchidglade cultivars often are quasi evergreen for me, with new growths starting right after leaf fall). Once a plant is leafless, I place them cooler, by about 5°C/10°F and in full light, as available. My climate is quite dark in Winter, so too much light would hardly be possible. Humidity is about 50%, but does tend to drop quickly, therefore one cannot call it constant. My potting medium is a sphagnum-bark-perlite-charcoal mix in mainly clay pots, making air circulation at the roots very good, but easy to retail any available moisture. Not problems, to date, but I do keep an eye on newer species and cultivars to find their sweet-point. I mist once a day, keeping an eye out for possible spotting on the dried leaf-sheaths, where molds or bacteria could take hold. Also, I run a ventilator for an hour or two in the afternoon to prevent dead moisture.

I'm glad you have started this thread, as there is a lot of info we could exchange. Dormancy can be very individual among plants. In any group of seedlings, some will simply adapt better than others.
cheers,
Jamie V.

[orchidsarefun]

so I do keep to the more light is better guideline and have noticed the bulbs turn a much darker shade of green. I also do the following
- unpot and store bare root *. I stand them up, packed in terracotta pots. This frees up a lot of space on grow racks and enables the other plants to get better light - they are all in a south or s-w facing aspect.
- divide where necessary and trim roots. I cut between bulbs with a sharp knife.
- sprinkle water on bulbs/roots about 1x per month on average.
My pileatum and my Mo Millenium Magic are both reluctant candidates for dormancy. I have to 'force' these by not watering come January.
Regarding the unpotting - I have tried to keep in pots as a comparison but in my conditions I have seen stronger new growth in the unpotted bulbs. The divisions also sprouted quicker.

* the exception to this has been seedlings in 2in pots. I have kept them in their pots until new growth starts.

[fishmom]

Thanks for your thoughts, everyone. I too have a pileatum that is staying green and spiking at the moment, and I have continued watering it lightly.

I haven't tried bare-rooting my plants for the winter, but I have one that grew in a pretty unbalanced way, and I plant to take it out of the pot as soon as it finishes dropping its leaves, so I guess I will be trying that.

I acquired one plant last year, a tenebrosum, that had a lot of black spots on the bulbs, so I am making sure to remove the papery bulb sheaths to try to prevent this. I know that in nature, the wind and weather takes care of this "cleaning", so I figure that I need to help a bit.

Jamie, thanks for the reminder that dormancy is individual with plants! A question: when you say you mist daily, are you misting the exposed roots, or the whole plant, bulbs and all? Do you think that water is taken up by the bare bulbs?

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[Regelian]

When I mist, it is a general veil of fine water that falls upon the bulbs, leaves, roots, et al. I use osmose water, as my tap water is hard in the extreme and I wish to avoid mineral build-up. I do not want them wet, generally, just to increase the ambient humidity. Bulbs certainly absorb moisture direct through their surface, as do leaves, simply not at the rate a root system does!
Jamie

[isurus79]

I throw them on my south facing windowsill and forget about them until April or so. They get water end of May.