Growing Orchids outdoors in Florida

[Carol Penry]

I have recently moved my orchid collection to a shade house here in Florida. The plants seem to be doing well for the most part. I'm concerned because they stay moist all the time. They are in a mix of bark and sphagnum moss in baskets and I have Phals, Cattleyas and Dendrobiums. Should I be concerned about too much moisture or leave well enough alone? With the rain I don't water at all. I would appreciate any input and am happy to be included as member of this group. I should have said I am new and look forward to learning a lot here.:

[mere_dog]

Hi Carol,

Where are you? I'm in North Port. So Phals, Catts, and Dends all have different moisture needs - as you probably know. I am still learning about growing orchids in FL, but your catts will need to dry - they won't tolerate wet bark even, in the long term. I have a number of Phals in sphag, which they love, but it dries out more than you'd think, over just a few days, even for me.

Is there good air circulation?

I'm no expert, but if you know your plants, then watch them closely and you'll detect the beginning of problems.

Carolyn

[Roberta]

I'm not in Florida, but it sounds to me like a perfect situation for mounted plants - all of these are epiphytes in nature, in humid climates with lots of rain. Phals too... I have found that they do really well mounted if I can keep them wet enough (or large bark in a basket) But you can't overwater a mounted orchid. Catts and Dens would probably also be happy in baskets with minimal medium (none at all for the Catts). If they get sufficient air, the damp won't do any harm.

[aliceinwl]

A switch to inorganic media like rock might also be an option. I have some potted in medium granite stones right now and it dries quickly but provides more moisture retention than bare root/mounting. I have some small Cattleya in stones and they want near daily watering. I think a change in media or mounting will be necessary to ensure the plants thrive under the changed growing conditions.

[SaraJean]

All of these are great suggestions! Probably 75%+of my orchids are either mounted (Dens, Catts, Bulbos, oddballs, and a few Phals), or in baskets with large bark or hydroton (Catts and a couple of Coelognye), baskets with small to medium bark (some other Dens), or baskets of sphagnum moss (mostly Bulbos, a Stanhopea, and a few other moisture loving oddballs ). I just take into account the moisture needs for the individual orchid when choosing the media. The ones I keep in pots typically are grown in hydroton (for larger Cattleyas). The taller, upright dendrobiums like Den Phals, Antelope type Dens, Latouria types, or something like a Den amethystoglossa, all do well in a mix of medium bark and perlite for smaller pots, bark and hydroton for larger pots. Any orchid in a pot gets a clay pot since it’s porous, plastic stays too soggy. Everything in my collection can get watered and/or rained on every day and most of my orchids rarely dry out between June and October. If you can keep enough air space around the roots, they should be fine to not dry out while the temps are still high in the summer

[Manfred Busche]

Hi there,
I would like to put a question to the more experienced members writing here (smile).

Not all, but most orchids require a marked 'Diurnal Temperature Variation' to flower -- i.e. a difference of day to night temperatures of, say, 12+°C (!Celsius!), the more of it the better.

I have seen hundreds of Cattleya plants for sale in one lot in Jakarta without any flower sheaths - Jakarta sits at sea level and Diurnal Temperature Variation there is very little.

How about Diurnal Temperature Variation in Florida, which is -as far as I know- a few meters above sea level ??

[ArronOB]

I would be concerned about having plants in pots which never dry out. I like my catts, dens and oncids to dry out one day in three. This shifts the balance in favour of the plants rather then the pathogens (most of which thrive in constant moisture).

I also grow outside year round in a shadehouse with a shade cloth roof and when we get rainy periods I pull a sheet of clear plastic over the roof after the second day.

[Ray]

Originally Posted by Manfred Busche

Not all, but most orchids require a marked 'Diurnal Temperature Variation' to flower -- i.e. a difference of day to night temperatures of, say, 12+°C (!Celsius!), the more of it the better.

HI, Manfred. Haven't heard from you in a long time!

Working mostly off my "gut feel" after 45 + years of growing, with only a small amount of "book learning" on the subject, I would have to challenge the "most" part of that statement.

The majority of cultivated orchids originate in tropical and semi-tropical environments where temperature variation is limited, no?

That said, I do know that physiological processes in plants can be strongly affected by temperature, so diurnal temperature cycling might aid in the accumulation of nutrient and energy stores, which certainly aids the blooming process, but I don't think it often acts specifically to trigger flowering.

---------- Post added at 07:57 AM ---------- Previous post was at 07:53 AM ----------

Originally Posted by ArronOB

I would be concerned about having plants in pots which never dry out.

Drying isn't really necessary, as long as there is plenty of air flow to the roots.

Many Florida growers use clay pots of LECA. It is very free-draining, does not decompose and compress, which is what leads to suffocation of the roots, and it holds moisture well. Semi-hydroponics - the same principle, but with a reservoir - is also good.

[Manfred Busche]

Subject : DTV = Diurnal Temperature Variation (please use Google Search).
--------

Hi Ray, thank you for the challenge.

While I salute your 45+ years of hands-on orchids growing in the US, I maintain what I have written in this thread (smile), and I substantiate as follows.

The vast majority of orchids, in nature, live in tropical hill and mountain country, where DTV, the difference between
day and night temperatures, is relatively high - the majority of orchids do NOT naturally live at sea level, though some
do (e.g. the 'Antilope Dendrobium' group).
In tropical hills and mountains DTV is high, at tropical sea level DTV is low, even very low ...

I have tried for 12 years to grow nursery-produced orchids in tropical Indonesia at sea level, and plants which
were bred at higher elevations would grow, but would not flower in my lowland garden. - And my favorites are
Stanhopea and Cattleya orchids, and these can definitely NOT successfully be cultivated under low DTV ...

And now I am growing in tropical Costa Rica at 700 meters of altitude, where daytime temperatures are 30°C and
where at night it is 17°C, and all orchid plants flower regularly and predictably ...

This thread is about growing orchids in warm to hot Florida, where DTV is low(??),
and I am not really sure how the conditions of warm lowland Florida compare to what I have said above ...
Summary of what I mean to say :: any orchids which were bred under high DTV, will not flower when grown under
low DTV. (smile)

And, by the way, no orchids like to have their roots wet all the time, not even in a breeze. (smile)

[Ray]

Originally Posted by Manfred Busche

Subject : DTV = Diurnal Temperature Variation

I will not refute the results, but maybe challenge the interpretation somewhat.

My (attempted) point was that a more significant DTV may permit some plants to develop their "stores" more easily than plants with smaller ones because the various chemical processes within the plant have different responses to temperature. Plants with adequate stores will certainly bloom more reliably that those without. That does not, however, prove that it was the DTV that triggered the blooming. (It might, but I have seen nothing that proves that irrefutably.)

It was long interpreted, for example, that phalaenopsis required a 10°F-15°F DTV to bloom. Dr. Wang (while at Texas A&M) showed that it wasn't a day/night difference that induced blooming, it was a 10 day to 2 week period of reduced average temperature that did it.

I have a friend in Central America that consistently held his phals above 90°F for several years. The grew and grew and grew, with most having 10-12 pairs of leaves, but never bloomed. He reduced the temperature to 70°F for two weeks, then returned them to the previously high temp conditions. Each of them threw a dozen or more spikes several weeks later.

I tracked the temperature in my own greenhouse for a year, and except for the month of August, there were 20°-25°F DTV's pretty much daily. None of my phals initiated spikes until about 6 weeks the average had dropped about 20°.

Another example of some cattleya species and hybrids - I don't care what DTV they may see, they bloom in response to short days, not temperature variation. Back to my original premise for a moment - it may be that those receiving a higher DVT may bloom better, but DVT is not the trigger.

Originally Posted by Manfred Busche

And, by the way, no orchids like to have their roots wet all the time, not even in a breeze. (smile)

Apparently my plants growing in S/H pots that have stayed wet for 25+ years haven't read that.