Growers: How Are you Dealing With the Heat?

[Ross]

The temperature is currently 92F (33C) and rising here in northern Minnesota, and there have been much hotter temps throughout much of the US. How are you keeping your plants cool? Do they even need cooling and at what temperature does the heat become critical? My questions relate to greenhouse growing, but responses from outdoor and in house growers would be good, too.

Here are the things I am doing to keep my greenhouse cool:
1. Aluminet shade cloth

2. Two 19" exhaust fans with intake vents on lower part of opposite wall.

3. HAF fans inside to mix air and eliminate hot spots.

4. "Custom" under bench misting system, using 54F(12C) well water. oke:

5. Finally, a big old oak tree which starts to shade the greenhouse around 3:00 PM.

Current greenhouse temp at 3:30: 90F (32C) and holding.

 

[Rick]

My Jaybird fogger has been running 4 or more hours a day on these super hot sunny days, and I have a single big ventilator fan that kicks in at the high 80's too.

I have seen a few temps in the low 90's in the upper half of the GH out of the line of the wet pad and fogger, so I'm pretty sure I have some areas near the wet pad still in the 80's

 

[Shiva]

My greenhouse is in full sun all summer long and even with white shade paint and ventilation, i find it too risky to leave the plants inside so out they go to a shade house where they are sprayed regularly to keep the leaves cool during hot weather. I have been using a shading net for many years but i plan to put a fiberglass roof over part of the structure next year leaving the sides open for ventilation.

 

[emydura]

I have a Jaybird fogger like Rick and I find that is very good at stopping the temperature from getting really hot. I also have an evaporative cooler which comes on when the temperature goes above 30oC, although that is rarely needed. In my glasshouse the temperature is very stable, irrespective of what the temperature is outside. The hottest it would ever get in my glasshouse is 31oC.

David

 

[Scott Ware]

It is nearly 2:00pm and a scorching 64F outside my greenhouse here in the Puget Sound area. According to a local TV station's website KOMOTV.com, Seattle has only experienced temperatures in excess of 80F for 78 minutes in all of 2011. I am NOT complaining.

 

[Brian Monk]

My shade house is open, so I just increase the shade in the summer.

And beer. Lots of cold beer.

 

[lindafrog]

Heat wave @ 95 is hitting us in northwestern lower Michigan.. where it rarely reaches into the high 80's. We have shade cloth on greenhouse and exhaust fan kicks in at 80. I make it rain couple of times a day for the restrepia and dracula along with plants that I don't put outside. Big bargain was a standing misting fan from closeout at Lowes-- $29 marked down from $130. Outside cymbidiums are doing okay in shade of cherry trees. The plants are in trays of water and I hose them down once in afternoon. I would be more worried about flower gardens and blueberry patch but we were lucky. A long soaking storm on Sunday night drenched our sandy soil with a couple of inches of rain. I feel for all our you in places south of us, which includes just about everyone !
Take care, keep your self and your orchids hydrated. I'm on my second gallon of solar green tea!
lindafrog

 

[jtrmd]

I think it was 96f here today with a heat index of 103f or something.GH still hasn't been out of the 80s yet.The stuff (Cyms,Vandas)that is outside is still doing good,but I stepped up the watering.

 

[valenzino]

Send me some sun please!Here is worst summer ever!Rain Rain Rain and Rain!!!

 

[Marco]

Personally....I stay in the A/C

 

[paphioboy]

Oh c'mon people... Orchid are not such wusses. Bit extra heat and sun won't kill them...

 

[Ross]

Oh c'mon people... Orchid are not such wusses. Bit extra heat and sun won't kill them...

Point well taken! What is challenging for us in extreme temperate climates is to build a growing area that can function for 5 months in subfreezing temps and then turn around and be equally functional in 90+F temps for three months. With 90F temps and full sun beating down on the greenhouse, without some way of dissipating the heat, such as exhaust fans, temps inside can raise rapidly to over 130 degrees, killing all the plants.

 

[SlipperFan]

Send me some sun please!Here is worst summer ever!Rain Rain Rain and Rain!!!

I sure wish we could do some trading! We need rain so badly, and that after a very wet Spring!

Oh c'mon people... Orchid are not such wusses. Bit extra heat and sun won't kill them...

I'm so glad you said that -- I was beginning to worry after reading all the previous posts.

My greenhouse got to 95ºF today -- the hottest it's been. I think the temperature outside was the same. I added an extra fan on the floor in the center. My other two fans, now set on high, are just above my head, and so pull the air mostly around the middle to upper part of the greenhouse. The vent fan pulls the uppermost air out of the greenhouse, bringing outside air in through the louvered vents and awning windows. So I expect the greenhouse will never be cooler than the outside air in the hot weather. The greenhouse will certainly be tested tomorrow when it's supposed to get to 97. My hope is that there will be a cloud cover during the hottest part of the day -- that should help.

I've thought about adding shade cloth, but so far I've not needed it.

 

[Eric Muehlbauer]

Nearly all my orchids are outdoors. I've stopped fertilizing the paphs...I hose them over nearly every day. They seem fine, my only problem is my lack of shade (thanks to last fall's tornado/microburst). My phrags and some of my paphs are scorched on some leaves...even the Barbata's have a burn mark or 2...just much shady places for them. No lasting damage though. Otherwise the increased sun has been a blessing...getting loads of veggies for the first time in years.

 

[Rick]

Oh c'mon people... Orchid are not such wusses. Bit extra heat and sun won't kill them...

I know I've had an occasional 100/103 temps in the old GH with crappier cooling systems in place. But with sustained day temps in high 90's and low 100's the plants definitely showed some were and tear. They definitely quit growing.

So the new systems are a welcome relief to stay below 95 so far. As Ross said the GH without cooling and ventilation could hit 130 on a sunny day, and then things would look like Death Valley. My alternative would be to make a big open shade structure under the trees and move everything outside (which is not unheard of in these parts).

Although we are not seeing record highs (maybe record consecutive >90 days), the regular rains we used to get this time of year have become very irregular, so air humidity is usually <50% on these hot days too. So I could put everyone out of the GH to get out of the heat, but then I'd have to add something to constantly mist to keep them from drying out.

So I might add more shade cloth to the GH before abandoning it to the great outdoors.

 

[Ernie]

95+. You mean June through October, Ross?

All you midwesterners should come down to Florida to cool of a little.

Even stuff that is supposed to like full to barely diffused sun (strap leaf vandas, Arundina, reedstem Epidendrums, etc) don't handle it in the middle of summer when it's hot. Providing mid-day shade helps a lot. Humidity and air movement also help a TON. Established terete vandas are going apes#$% now though.

To top it off, we're fully into the wet season here, so most days have better than 50% chance of precip (anywhere from drizzles that evaporate before hitting the ground to torrents) somewhere between lunch and dinner (usually around 5-6 pm, just as I'm hopping on my bike to commute home- feels great actually!). So the rain barrels are ever-full and we water less frequently than in spring and fall since mom nature helps out. With all the moisture and humidity, gotta watch fungal and bacterial issues. And mosquito blooms.

Oddly, the tropical storms in the Atlantic (Brett & Cindy) moving N, NE are sucking the moisture from us, so we've been dry the past five days or so.

 

[Rick]

Pretty cool.

I just read out the data logger which showed I haven't cleared 92 in the GH with outside ambients hitting close to 100. Also the peak temps(above 90) are only lasting for no more than 2 hours.

So as long as we don't have a power outage.......:sob:

 

[John M]

So as long as we don't have a power outage.......:sob:

'You a gambler, Rick?

 

[John M]

Send me some sun please!Here is worst summer ever!Rain Rain Rain and Rain!!!

So, where is "Here"? You haven't included your location in your profile. It REALLY helps to know that. It puts things into perspective.

 

[tocarmar]

It was about 95 today with heat index at about 100. Tomorrow & friday are going to be hotter. I have most of mine in the basement about 70 now. The only ones outside are the Cyps, & 1 Cymbidium which only get morning sun & shade the rest of the day. I have misted them 2x's a day with the heat.