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Author Topic: Temps and humidity level inside greenhouses.  (Read 6778 times)

NewGen

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Temps and humidity level inside greenhouses.
« on: November 11, 2012, 02:20:34 PM »
Humidity: 70% - 85%.
Temperature: 65F - 95F.

Is 95F too high?
Thanks,

FlyingFoxFruits

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Re: Temps and humidity level inside greenhouses.
« Reply #1 on: November 11, 2012, 03:32:13 PM »
great topic!

95f can be bad for certain fruits on the tree, but generally that temp has been fine for me!

I've gone unto about 104F for a few hours without serious damage!

depends on humidity, circulation, duration of exposure and also the plants being exposed!

good luck, keep us posted!!!

NewGen

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Re: Temps and humidity level inside greenhouses.
« Reply #2 on: November 11, 2012, 04:04:58 PM »
Just put up the 2 greenhouses yesterday, this morning I saw temp at 95F, and humidity at 86%. I'm not worried about the humidity level, but the temp is a concern. The south-facing windows have no blind or curtain, so I think I'll temporarily tape up some screening material to filter some of the sunlight. I lifted up the window to the greenhouse and within minutes the temp dropped to mid 80s, humidity dropped to 50s%. Top row middle is the one thing I don't want to kill, a guanabana. I think the duration of sun exposure is approximately from 8 AM to 4 PM. I think the plants will be fine with mid 80s F all day long, high humidity is good for 'em.


edself65

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Re: Temps and humidity level inside greenhouses.
« Reply #3 on: November 11, 2012, 06:05:33 PM »
My temp inside my greenhouse has been between 55 and 98 F. I had a solid week of night time temps in the low 30s. My little propane heater on the lowest setting has done a good job of maintaining the mid 50's at night and then with the sun and heater off during the day I have the mid to high 90's. The plants are still growing well! I still have a lot of new growth and plants blooming.

Ed

NewGen

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Re: Temps and humidity level inside greenhouses.
« Reply #4 on: November 11, 2012, 08:44:51 PM »
Ed,
Your greenhouse must be outdoor, right?
How big is it?

edself65

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Re: Temps and humidity level inside greenhouses.
« Reply #5 on: November 11, 2012, 08:49:49 PM »
It is a 15x7x7. Yes it is outdoors.

Ed

JeffDM

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Re: Temps and humidity level inside greenhouses.
« Reply #6 on: November 11, 2012, 09:03:20 PM »
I'm currently searching for an inexpensive portable greenhouse enclosure approx. 12L X 7W X 7H - the kind with the metal or plastic frames and a  polyethylene covering.
Any recommendations would be helpful.
I also saw one product that was all the brackets needed to construct a greenhouse out of 2"x2" lumber that would be purchased separately, but could not find any reviews to help guide me.

stressbaby

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Re: Temps and humidity level inside greenhouses.
« Reply #7 on: November 12, 2012, 08:05:57 AM »
It may be both the temperature swings and the absolute temps which create trouble.

My outdoor 20x23 GH hits 107F in the summer (despite max efforts at cooling with mist/shade cloth,ventilation, etc).  The plants are acclimated I guess and there is no apparent adverse effect that I have seen.

The smaller the GH the more difficult temp regulation is.  If it were me I might sacrifice some humidity to even out the temps.  The greater the difference between day and night temps, the greater your internodal length will be..."leggy" plants can be the result.
« Last Edit: November 12, 2012, 08:09:20 AM by stressbaby »

CoPlantNut

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Re: Temps and humidity level inside greenhouses.
« Reply #8 on: November 12, 2012, 03:31:46 PM »
It may be both the temperature swings and the absolute temps which create trouble.

My outdoor 20x23 GH hits 107F in the summer (despite max efforts at cooling with mist/shade cloth,ventilation, etc).  The plants are acclimated I guess and there is no apparent adverse effect that I have seen.

The smaller the GH the more difficult temp regulation is.  If it were me I might sacrifice some humidity to even out the temps.  The greater the difference between day and night temps, the greater your internodal length will be..."leggy" plants can be the result.


Yes, the day/night temperature swings can cause leggy plants, unless you can reverse natural conditions and have warmer nights than days, in which case you'll get very compact plants (and a large energy bill, and possibly some chlorosis).  There's evidence that having the first few post-dawn hours of the morning be the coolest period of the day (cooler than the night) can decrease internode distances for most plants without being too impractical or causing the plants to get chlorotic.  There's an excellent summary article on the research that has been done on this at the University of Florida's website:

http://swfrec.ifas.ufl.edu/docs/pdf/vegetable_hort/trans_ph1.pdf

For small indoor greenhouses (like my 12'x15'x7') you can get a $100 6-amp automatic fan speed controller that lets you set a minimum and maximum temperature for the day and night periods, and when connected to a fan ($200 or more for a good one capable of the necessary cubic feet per minute for my setup) and a swamp cooler (made my own for $30) can keep temperatures from getting too warm during the day while still keeping humidity high.  You do need somewhere to vent the warm humid air other than inside your house though...

   Kevin

JeffDM

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Re: Temps and humidity level inside greenhouses.
« Reply #9 on: November 23, 2012, 06:37:53 PM »
I finally got my little portable greenhouse fixed up with a thermometer, humidity gauge and a small heater with temperature gauge and low (750 W) setting.
Of course this means the temperature inside it will probably fluctuate between 65° F at night and about 90+° F during the day until I check my electric bill to see if I can run the heater a little hotter.
The humidity seems to be running between 45% and 85%, but I think the cheap gauge on the thermometer reads a bit low.
I'm trying to balance things so I don't have to check it so often.
Now I need some more shelves and some more plants to stuff inside it.







Tim

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Re: Temps and humidity level inside greenhouses.
« Reply #10 on: November 23, 2012, 07:13:39 PM »
Nice setup.  From personal experience, unless they're super rare poly seeds, I wouldn't waste whatever limited space you have within your greenhouse for mango seedlings.  I think my area gets colder than yours in PQ if I'm not mistaken?  Aside from recent grafts, I never protect any of mine - none died thus far.  Save the space for more rare stuffs ;D
Tim

JeffDM

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Re: Temps and humidity level inside greenhouses.
« Reply #11 on: November 23, 2012, 07:30:43 PM »
Nice setup.  From personal experience, unless they're super rare poly seeds, I wouldn't waste whatever limited space you have within your greenhouse for mango seedlings.  I think my area gets colder than yours in PQ if I'm not mistaken?  Aside from recent grafts, I never protect any of mine - none died thus far.  Save the space for more rare stuffs ;D

Thanks, right now I've got a little more space than I have stuff and I wanted to see if I could get things to grow a bit better over the winter months in the little greenhouse.  A lot of the small pots have papaya seedlings from a store bought papaya and I'm just experimenting to see how well they will grow.  The bigger pots are papaya seedlings started from seeds I bought from Aloha Seeds in El Centro and one plant bought at a nursery.
Since my south facing backyard gets hammered by the sun I thought the mango and avocado seedlings would be a bit happier in the greenhouse.

siafu

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Re: Temps and humidity level inside greenhouses.
« Reply #12 on: November 23, 2012, 08:33:31 PM »
Hi,

You should also consider adding a fan to have some air movement in the enclosure. High humidity and still air can lead to fungal problems.

Don't worry too much with temperature, provided it does not go much above 95F or so.

I would worry more about pests, such as spider mites. They can cause a lot of damage in a short while.
 
« Last Edit: November 24, 2012, 02:20:23 PM by siafu »
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JeffDM

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Re: Temps and humidity level inside greenhouses.
« Reply #13 on: November 23, 2012, 08:39:18 PM »

Hi,

You should also consider adding some a fan to have some air movement in the enclosure. High humidity and still air can lead to fungal problems.

Don't worry too much with temperature, provided it does not go much above 95F or so.

I would worry more about pests, such as spider mites. They can cause a lot of damage in a short while.

Thanks, I have the little greenhouse positioned so I can get some air flow by opening the front and back flaps, but maybe I should open them a bit more than I have been during the day.

JF

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Re: Temps and humidity level inside greenhouses.
« Reply #14 on: November 25, 2012, 03:52:29 PM »

Hi,

You should also consider adding some a fan to have some air movement in the enclosure. High humidity and still air can lead to fungal problems.

Don't worry too much with temperature, provided it does not go much above 95F or so.

I would worry more about pests, such as spider mites. They can cause a lot of damage in a short while.

Thanks, I have the little greenhouse positioned so I can get some air flow by opening the front and back flaps, but maybe I should open them a bit more than I have been during the day.

Very nice Jeff. Keep those bricks wet....it's hard to control the temp in those little GH but make sure you have good air circulation.

JeffDM

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Re: Temps and humidity level inside greenhouses.
« Reply #15 on: December 13, 2012, 08:49:52 PM »
Just got my latest electric bill and decided that the plants in my greenhouse didn't need to be so warm at night.
I also decided that the outdoor Christmas lights didn't need to be on for so long.
:)

Pancrazio

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Re: Temps and humidity level inside greenhouses.
« Reply #16 on: December 14, 2012, 07:30:18 PM »
I got 23F outside as minimum last week, and 40F inside as minimum. The mango is still alive but, as during last winter, a black spot as appeared on the new growt. I think it is the same bacterial/fungal disease, it won't go away till the climate will be more dry. Too bad my max temperature are around 70F inside, so i guess it is enough to let the sickness develop.
And now i have to understand if i should cut or not.
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bangkok

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Re: Temps and humidity level inside greenhouses.
« Reply #17 on: December 16, 2012, 08:23:25 AM »
Just got my latest electric bill and decided that the plants in my greenhouse didn't need to be so warm at night.
I also decided that the outdoor Christmas lights didn't need to be on for so long.
:)

Maybe you can put some big plastic buckets full of water in the greenhouse (with or without lid) so they catch sunshine in daytime. Then the water warms up and at night will spread the warmth. So you can save energy and get a better average temp in the greenhouse. If you don't use lids on the buckets then you also get a higher humidity.


stressbaby

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Re: Temps and humidity level inside greenhouses.
« Reply #18 on: December 16, 2012, 08:36:22 AM »
Just got my latest electric bill and decided that the plants in my greenhouse didn't need to be so warm at night.
I also decided that the outdoor Christmas lights didn't need to be on for so long.
:)

Maybe you can put some big plastic buckets full of water in the greenhouse (with or without lid) so they catch sunshine in daytime. Then the water warms up and at night will spread the warmth. So you can save energy and get a better average temp in the greenhouse. If you don't use lids on the buckets then you also get a higher humidity.

This is great in theory but in reality it doesn't work.  The water will gain energy during the day but it starts losing its energy as soon as the temperature differential favors heat loss.  This is generally long before you will actually need the heat.  This might work with an enormous amount of thermal mass but generally for this to work you must actively manage your thermal mass by moving it around with pumps and so forth.

Pancrazio

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Re: Temps and humidity level inside greenhouses.
« Reply #19 on: December 16, 2012, 08:36:59 AM »
That's exactly what i do, and i must say that i'm amazed, water alone get me a gain of 10C, making heating useless.
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bangkok

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Re: Temps and humidity level inside greenhouses.
« Reply #20 on: December 16, 2012, 09:04:42 AM »
Well the principle of this idea sure works. In Holland the new heatingsystems pump warm water deep into the soil in the summer and in the winter we pump it up and heat the houses with it.

You can use a small waterpump and pump it through a black waterhose in the sun and then let it fall in a big waterdrum. Then you loose electric energy for the pump but thats sure cheaper then heating.

Warm water (also warm air) tends to rise and cold water (or air) tends to sink down. Maybe you can use that principle by heating water which is lower then the big storedrum so if it heats up it will rise up into the drum. Then new colder water will sink out of the drum into the black hose that is being heated.

Well i think if i play with it i can find some system that works pretty well and for free. Maybe you can use double glass windows to isolate the greenhouse (2nd hand ones or so) or isolate the walls or floor.

I think Pancreas also uses something like this and i can believe that you win 10degree's will win.

Wayne

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Re: Temps and humidity level inside greenhouses.
« Reply #21 on: March 27, 2013, 04:30:38 PM »
My greenhouse gets up to about 115 degrees Fahrenheit for 7 months each year.  The humidity level is about 90, which protects the plants.  I don't have a problem with heat, but I do have a problem with cold at night.

fyliu

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Re: Temps and humidity level inside greenhouses.
« Reply #22 on: March 28, 2013, 10:40:33 PM »
Wayne, welcome to the forum. What do you raise in your hot greenhouse? Must be some really tropical plants.

 

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