How hot is to hot for JBP in a Green House?

Drew

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I've been growing JBPs in a greenhouse since the start of the year to give them a head start in my climate and was wondering how hot is too hot for them before they will suffer? yesterday it got to 50 degrees celsius (or 122 Fahrenheit) and 95% humidity. They all seemed fine. they get direct sun from 11:30am till sunset around 9pm
 

Drew

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yeah I wast expecting it to get that hot either... I am installing roof vents to see if this cools it down a bit...
 
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I started my seeds in the greenhouse this year but due to very hot 2 weeks in march, they all got cooked, even the soil was moist.
The germination ratio was very poor, once moved outside, some of them germinated, but not the way i wanted.
My problem is i need to keep door and window open so it doesnt get too hot, i try to keep temperature around 30 Celsius, however with that temp, humid is very low, maybe 30% (otherwise i will have 50degrees or more - same as you)
I had to move all seedlings out now, only tomatoes and other veg are left, also some tropical plants and couple of small ones that seems to like hot,
Larch seems to be loving it, some prunuses also, albizia, baobab, fuchsia, cotonaster, all are fine, maples not doing well, unfortunately Azalia got toasted as well:(

Vent will help you, however until you have door open and bit of draft, it will still keep very warm inside, problem is humidity that is going low
I installed shading net yesterday on the side when midday sun shines the most, i will see how it goes, its cloudy today so cant say
 

Anthony

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Tropics here,

Max for around 15 to 30 minutes 93 deg,F for April / May.
Then drops back to high 80's rest of the year.
Lowest low is 64 deg,F - Christmas to February once or
twice a week, But mostly 70 to 75 deg.F

Humidity 80 to 45 %

All from seed.
Good Day
Anthony
 

Drew

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Thanks.. very helpful replay. I have mostly 4-7year old JBPs in pond baskets and a few more established JBPs in bonsai pots. Have you just had JBP seedlings in there?
 
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Yes i had seedlings there, some just germinated some year old, they seems to like it until certain point, so when was cold outside like 5 degrees, there was about 20 in the greenhouse and they loved it, but once it started to get hotter outside and temps reaching around 35 in the greenhouse, they slowed down, needles started to drying out in some parts.
I had prepared soil for repotting in the container that was closed and under the table out of direct sunlight, went repotting one evening and i could feel the soil being very warm in the hand and nearly dried out.

Also not sure if that was because of the heat, but had a scots pine there as well, probably 7-10 years old, still in training, but instead of extedning the candles, it started needles straight away, another one that i had same age but outdoors, candles were extending very nicely.
 

amatbrewer

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I don’t know if this is helpful as I don’t have JBP, but I have used a small greenhouse for plants in need of special attention (primarily more humidity and/or protection from freeze/frost). The previous location of my greenhouse (I recently moved it) received full mid-day and afternoon sun, so while the air temps may have been low (even down to freezing at night sometimes) the greenhouse could get extremely hot during the day regardless of how much ventilation I provided (automatic vents & fans), easily in excess of 110F (43C) on many days.

I experimented with an automated irrigation system and found that if I used the soil temperature rather than the air temperature to trigger the water, I could keep the roots from overheating. And while it was not ideal (avoiding over watering took a lot of tweaking), it did work to protect some fragile trees more than using air temp, humidity, or even soil moisture levels (yes, I tried each).
 

Clicio

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Above 35C the metabolic processes burn more carbon than is fixed by photosynthesis. IOW, trees are not growing.
Above 45C roots and other tissues in the tree are certainly dying.
As temps here get to 35 for days (or weeks lately) in the Summer, it gets evident the trees stop to grow. Summer dormancy I guess.
But maples... Maples suffer.
 

jimib

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I put an opaque tarp over my small greenhouse to keep the heat down. It knocks it down 15/20 F. Now all my stuff is outside so I took it off. Yesterday without the tarp, roof vent and door open, at 83F outside it was almost 100F inside.
 

Anthony

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Always amazed at what you guys can handle temperature wise.
Just high 80's in the lowlands and humidity at 80 %
and I am covered in heat rash.

Up North in Port of Spain, I live in the air conditioned malls.
No air conditioners needed at home.

Clicio, the maples can live under our trees.
They can handle high 80's in the bright light.
Good Day
Anthony
 

Clicio

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Clicio, the maples can live under our trees.
They can handle high 80's in the bright light.
Anthony
@Anthony thanks, I know it well, shade in the summer.
But even dapled afternoon sun can burn its leaves. I guess a 40% sun cover will work better in the summer here.
 

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