Paphiopedilums and photoperiod

[Ernie]

Kevin,

Especially with fluorescents, one is usually well below the intensity the plants would wish for. Tacking on hours gives them the light they want just over an extended period. Like sipping a little tea all day versus sucking down a Red Bull (well sorta). Agricultural literature supports this. More than 16 h/day gives no benefit and can stress plants. Daylength sensitive plants of course would disagree. Paphs seem to love it.

-Ernie

 

[Kevin]

Ahh. Thanks. That helps. So, extended daylight does put stress on the plants. I hadn't thought of the low light intensity from growing under lights. How about HID bulbs? Is 16 hrs year-round good even with using these? I have all my plants outside for as long as they can take it, which, in a good year, is 4 months. Since there is a long day length here in the summer, when I bring them in, I give them 12 hrs, then 11, then back to 12 before bringing them back out in spring. I figure that gives them a seasonal change. Now, perhaps a lot of plants don't need this, but it can't hurt, and it saves money. I grow just about everything I can, and probably some of them appreciate the change, but I don't know. Like I said, it can't hurt. (I like the saving money part too ).

 

[Ernie]

For us, the lights being on helps keep the heater from running in winter. The majority of our collection is in an insulated garage. In the western suburbs of Chicago, we see crazy hot summers (many 90+ F days) and pretty dang cold winters (a week or three of sub-zero in winter). We are 35 miles west of the Lake, so we get roughly the hottest summers and coldest winters of greater Chi-town here IMO. It's a tradeoff. In a completely "closed system" here, I'd reverse the seasons with the plants seeing the longer days in our freezing winters to benefit from the lights' heat, but shorter days in summer so the lights wouldn't add even more heat to our hot days here. If your plants grow and bloom, dont' mess with it IMO.

-Ernie

 

[goldenrose]

..... I give them 12 hrs, then 11, then back to 12 before bringing them back out in spring. I figure that gives them a seasonal change. Now, perhaps a lot of plants don't need this, but it can't hurt, and it saves money. I grow just about everything I can, and probably some of them appreciate the change, but I don't know. Like I said, it can't hurt. (I like the saving money part too ).

an hour makes a difference?

 

[gonewild]

Kevin,

Especially with fluorescents, one is usually well below the intensity the plants would wish for. Tacking on hours gives them the light they want just over an extended period. Like sipping a little tea all day versus sucking down a Red Bull (well sorta). Agricultural literature supports this. More than 16 h/day gives no benefit and can stress plants. Daylength sensitive plants of course would disagree. Paphs seem to love it.

-Ernie

I'm not sure I would agree that more than 16 h/day will stress plants.
In what way is the plant stressed by longer daylength?

 

[Ernie]

I'm not sure I would agree that more than 16 h/day will stress plants.
In what way is the plant stressed by longer daylength?

I've seen stressed plants that got *no* night that recovered after reducing the daylength to reasonable levels. Otherwise, probably won't make much difference if one did, say, 18h days. I've stumbled across agricultural literature (probably soy beans or corn?) which said more than 16h might not hurt, but has no benefit (a waste of electricity beyond 16h essentially). Unfortunately, as far as I know, no such study has been done on orchids??? Make sense?

-Ernie

 

[Ray]

I think you've hit upon it, Ernie.

Just like feeding, in which the concentration of fertilizer times the frequency of application determines the mass of nutrients delivered - and we know too much can be a problem - it seems logical that plants probably have an upper limit on the "mass" (intensity x duration) of PAR photons they can accept before the ongoing "forced" photosynthetic chemical reactions interfere with- or overwhelm the others that go on.

It also wouldn't surprise me if some of those processes need darkness as a trigger to occur. I won't claim to know diddly about it, but don't CAM plants only open their stomata at night? Maybe a certain amount of darkness is required to allow time for the "balancing" reactions to catch up with those that occur in the light.

 

[Kevin]

an hour makes a difference?

If terms of the plants, probably not, but perhaps for some. For energy savings and money, yes, absolutely. I've got a 1000W HPS. I may even go down to 10 hrs.

 

[musiclovertony]

This might sound crazy, but I actually check the weather channel every day and adjust my timer so that it coincides with the local sunrise and sunset. That way my plants experience seasonal changes at a less than shocking rate of change.

Is there any reason I should not be doing this?

 

[SlipperFan]

Interesting concept. But we live in an area that has long-day summers and short-day winters. I think the more tropical countries that most of our orchids come from have more even day-night periods throughout the year.

 

[likespaphs]

This might sound crazy, but I actually check the weather channel every day and adjust my timer so that it coincides with the local sunrise and sunset. That way my plants experience seasonal changes at a less than shocking rate of change.

Is there any reason I should not be doing this?

the only reason i have for not doing it is that it's a pain in the...well, you know where.
there are timers out there that can do it automatically....


i think i remember an australian member of the forum who said that they have significant shade on his/her greenhouse because the days are so very long

 

[Ernie]

Is there any reason I should not be doing this?

The only reason you should match your daylength to Minneapolis' is if you're growing plants that grow in Minneapolis. Go to the weather channel and check the sunrise/set for Vietnam, India, Borneo, Thailand, China... Then consider Peru, Ecuador, Panama, etc for your Phrags. Then tack on a fudge factor for elevation... You get the point. These things are tropical to sub-tropical. Most will see about 12 h light year round. But, Like I said earlier, for fluor gardens especially, growers give them barely enough light usually, so a slightly longer daylength will help offset that.

 

[musiclovertony]

The only reason you should match your daylength to Minneapolis' is if you're growing plants that grow in Minneapolis. Go to the weather channel and check the sunrise/set for Vietnam, India, Borneo, Thailand, China... Then consider Peru, Ecuador, Panama, etc for your Phrags. Then tack on a fudge factor for elevation... You get the point. These things are tropical to sub-tropical. Most will see about 12 h light year round. But, Like I said earlier, for fluor gardens especially, growers give them barely enough light usually, so a slightly longer daylength will help offset that.

Oh you have a very good point. hmmm...so many things to consider! I grow with HID lighting, so I'm not worried about too little light. I think I might be giving too much light this time of year, since we're around 16 hours a day right now

 

[SlipperFan]

Oh you have a very good point. hmmm...so many things to consider! I grow with HID lighting, so I'm not worried about too little light. I think I might be giving too much light this time of year, since we're around 16 hours a day right now

Just remember, these are tropical plants, not temperate...

 

[Shiva]

Interesting reading! Thank you Ernie and all. It helps everyone to read about this. Though I still wonder if HID lamps require longer days.

 

[Ernie]

Though I still wonder if HID lamps require longer days.

Depends on what's under them, how far, how hot, wattage, output spectrum...