Seasonality of Cattleya species growth and flowering

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Nov 29, 2008
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Bloomington, MN
I grow unifoliate Cattleya species as much as a biology experiment as for the flowers. I grow indoors with LED lights and have good control of day length, light intensity, and temperature. I have wondered whether the growth and blooming cycles of the species described in Chadwicks’ The Classic Cattleyas reflect native growth or what is traditionally observed in greenhouse culture far north of the equator using only ambient light.

I am several years into my focus on Cattleya species and have plants that root, initiate new growth, and bloom off-schedule from Chadwick’s descriptions. I have attributed this to my active experimentation with growth conditions and the plants not being fully acclimated to my conditions.

However, some of you Cattleya experts have large established unifoliate species collections and long experience so I am hoping you will comment on how on- or off- schedule your species grow and bloom with your conditions compared to Chadwick’s descriptions.
I am guessing that these are guidelines or averages rather than very clean and clear cycles. I would expect that there will be variation in blooming and growing cycles for all species if you look hard enough at individuals. Several of the species occur in quite extended geographical ranges. Look at lueddemanniana which has a long narrow tongue of distribution from the coast inland into the mountains. This should also produces some variation in growth cycles.
I guess I am thinking of plants like( trianae 'Cashen's' x self) that has bloomed for me Aug 2018, October 2019, August 2020, and August 2021. So far away from the December-February that is published. Is it my culture or just an unusual plant? I have a few other examples of species consistently blooming many months away from the expected. I also have some blooming all over the place like my mossiae 'Willowbrook' which bloomed Feb 2018, Nov 2018, May 2019, Apr 2020, Jan 2021, and Aug 2021. I know this may be a hybrid with lueddemannia but those should both still bloom in the spring. It is clearly confused by my conditions.
My bet is temp fluctuations and you can’t rule out nutrient applications. In the Nov. installment of the AOS bulletin on led growing ‘Let There Be Light’, Kelly mentions keeping her led lights on 12hr intervals year round. She grows the same species under lights as she does in the outside greenhouse and says they bloom at the same time of the year, and has not found an instance where this was not the case.

If it’s not the day/ night light interval, and you’ve bloomed it successfully under the current led lights, then it has to be something else you are introducing to the growing environment that’s triggering or inhibiting the blooming cycle. Temps and nutrient application. I have a feeling it has more to do with the day night temperature difference. Hardest variable to nail down is the 10+ degree drop of night time temps in the summer.
I agree that it must be the subtle interplay between day and night time temperature along with water and nutrition. I vary my day length between a minimum of 11.5 hours mid winter to 13.0 hours mid summer, trying to be close to the natural environment for most of the unifoliate Cattleyas. I also modestly decrease the light intensity late fall and mid winter as happens even around the equator. I do get at least a 10 degree difference between day and night, but I think the coordination between day length and the temperature change is important and I am still working on this. I am also now gradually reducing nutrition through the fall into Winter with an increase through Spring into Summer. I am using a complete fertilizer for RO water and monthly use KelpMax. Maybe the bottom line is that these experiments take years to work themselves out and I have to be patient in my older age! I was just looking from support from others who are growing and blooming successfully, but not always at the expected time.
There are some many factors that could be at play here.
We know from Chadwick that the flowering of labiata can be controlled day length. So could others.
I have a lueddemanniana clone that insists on growing in summer and flowering in autumn like labiata. All my other clones do as normal with this species. Several are just starting their new growths now and will flower in the spring. House lighting doesn’t seem to affect them.
My warneri clones seem to be able to change their growth habit at will. The smaller, younger plants generally grow during the spring and summer when the weather is better. However as they mature, they start to grow over winter and flower in the spring, as they should. Go figure.
Most of my species follow the ‘rules’ and flower when you would expect them to but a few do not.
I would really like to read someone's month by month description of growth and flowering of native populations of the species (with accompanying daily light integral and minimum/maximum temperatures). I haven't seen such a thing. How much variation within a population is there? I think much of what we read is a consensus of growth and flowering in northern hemisphere greenhouses.