Freeze Warnings, BBBRRRRRRRR

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The Toker

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Here is my little girl that I left outside to bloom. It made it through the frost last night. Tonight they are calling for freeze warnings, thought I would get some pics and cover her up. What do you think. Hello from mid MI

My indoor room
http://www.marijuanapassion.com/forum/showthread.php?t=30534

Indoor blooming
http://www.marijuanapassion.com/forum/showthread.php?t=31418

Buds!!!!
http://www.marijuanapassion.com/forum/showthread.php?t=31476

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Back at ya from Seattle...Toker great idea man..and those look mighty tempting ..lol..Thanks for shareing with me my friend


KEEP M GREEN
 
hey Toker, lookin' good man. yeah, possibly high 20's. my 'lil woman, and i just finished puttin' the cold frames over our gardens'. i stuck plastic drums' over my outdoor girls. second night in a row i had to turn on the heater. people been sayin' early snow here, and have been speculatin' a hard winter...
 
Took the bag off this morning and were the bag was touching the cola, the top of the bud was frozen. Will this be OK or should I harvest it now? Anybody????
 
did you tie the bottom of the bag closed so the frost could'nt enter the bag? it sounds like you did'nt and some moisture entered the bag. it's gonna freeze again tonight too toker. tie the bottom closed as best as you can. lets hope it did'nt do irreversible damage already. watch it close over next few days'. you'll know if the frost did any damage by tomorrow by latest. good luck T.
one of my tops got broke off last night. it possibly happened this morn. when i took the plastic drum off it. maybe it also froze to the drum?:confused: ...
 
The Toker said:
Took the bag off this morning and were the bag was touching the cola, the top of the bud was frozen. Will this be OK or should I harvest it now? Anybody????

Get a couple of bamboo canes and stick them in the ground, put the canes into the corners of the bag so the canes are holding the bag off the plant ;)

Green bags dont stand out so much.
 
i just picked up a bunch them babboo canes at wal-mart. they painted green and come in budle of like 20 canes bout 4 ft long. they were clearanced out for 2 bucks
 
If you have easy access to them you can mist them too. Sounds crazy but it will help protect them from frost/freeze. Myself, I pulled 16 of 25. But the Daywreckers were as big around as softballs so I am good.;)
 
Something to do with the water crystallizing forming some type of insulating barrier, check into it, it is for real.
 
SFC said:
Something to do with the water crystallizing forming some type of insulating barrier, check into it, it is for real.

i don't think i would be spraying my bud on a night it's going below 30 here. it will turn black, and it will die. (maybe a sugar water or something heavy?, i don't really know). im with bbp, sfc. i'd have to see the benefits first. i've had two hard frosts already. one night 29, and one 31. even my best efforts could'nt save all.
 
does MJ show obvious signs its done for after a frost. or will it gradually look sickly and then shrivel an die?
 
banjobuzz said:
i don't think i would be spraying my bud on a night it's going below 30 here. it will turn black, and it will die. (maybe a sugar water or something heavy?, i don't really know). im with bbp, sfc. i'd have to see the benefits first. i've had two hard frosts already. one night 29, and one 31. even my best efforts could'nt save all.

orchard growers do it with fruit trees, to protect both fruit and blossoms "I believe". But I would be hesitant to apply it to mj flowers.
Though it 'might' work, you aren't dealing with a huge volume of trees. Covering plants with a sheet, blanket, tarp, ect. works best if it does not touch the plant. Any place that the covering touches the plant, there is a chance of freezing.
 
This is the concept behind the theory, if it works for vines, it works for other delicate plants.


Frost protection thanks to water



... or how water saves the day.

In early spring, weather can be very capricious and every farmer fears temperature changes. When the weather gets warm enough, the vine buds and benefits from the sun. But all of a sudden the thermometer decreases below 0°C (32°F) during the night and the irreversible happens : the newly-born buds are killed by the frost. Damn'it ! The grape harvest will be bad this year...

Hopefully there is an ancient technique to prevent that. And what makes it almost magic is that only water is needed to save the crops. The idea is to keep an eye on the thermometer and when it's heading for 0°C, start spraying the vine (ar any other fruit tree) with water. A miracle is about to happen : if the weather does not become too cold, the poor defenseless buds will be saved.

There is no miracle

Now I swap my farmer's hat with that of a physicist and this castratrice action replaces all magic with plain factuals. No it is not a miracle if the buds were saved by water, it has to do with thermodynamics.

Thermal exchanges are energy exchanges and energy is expressed in Joule. When you heat an object, you give it a certain amount of energy. The temperature change reflects the amount of energy given. From the definition of enthalpy :

ΔH = cp ΔT, (cp > 0 in J/kg/K, T in K or C)
When the air is cooler than the object, it is in fact the object that heats the atmosphere. It gives away energy (&#916;H < 0) hence its temperature decreases (&#916;T < 0) and the buds frost.

This is the case when there is no phase change. During a phase change, the temperature (of a pure substance) is constant (the phase change temperature) although energy is still exchanged. The heat absorbed by a substance as it changes phase from liquid to solid is called the Latent Heat of Fusion Lf and it is expressed in J/kg. The Latent Heat of Fusion of water is Lf = 334 kJ/kg which means that you must give 334 kJ to a 1 kg ice cube at 0°C to melt it completely (expose it for 5 min to a 1000 W radiator). By the end of an operation you will have 1 kg of water at 0°C.

1 kg of water releases 334 kJ when it changes from liquid to solid phase. The cold freezes the water which stays at 0°C during this process and protecs the buds. This is why farmers spray their vines with water when the weather gets cold.

What is it worth ?

Now let's get an idea of how efficient this technique is. Newton's conducto-convective law established a relation between the difference of temperatures between two substances and the amount of energy exchanged :

&#934; = h (Tair - Twater) is the thermal flux (W/m2) released by the water into the atmosphere.
h is Newton's conducto-convective coefficient which ranges typically from 5 to 1000 W/K/m2.

| XXX |
| XXX | vine branch surrounded with water
| XXX |
| XXX |
Let V be the volume of water, m the mass of water and S the surface in contact with the atmosphere. The energy released by the water when it changes phase is Q = m · Lf. The power exchanged is P = S · h · (Tair - Twater). Hence the water will frost in t = - Q / P seconds :

t = - m · Lf / ( S · h · (Tair - Twater) )
Here is the model :
Length of vine branch : 1 m
Diameter of vine branch : 0.01 cm
Mass of water : m = 100 g
Latent Heat of Fusion of water Lf = 334 kJ/kg
Exchange surface : S = 0.03 m2
Newton's conducto-convective coefficient air/water : h = 50 W/K/m
Tair = -5 °C
Twater = 0 °C
t = 4446 s = 1h 14 min

Closing words

This method does indeed save the buds from frost but the temperature must not be too low for it to function correctly. The same idea was used to prevent cellars from freezing during cold winters. People just filled them with buckets of water because they release energy when they change phase.

So it looks as if it could go down to minus 5 but the surface will register 0 for 1hr 14 mins.


here is the fun bit .... who volunteers to try this on their buds?

:rofl:
 
(i think), that spraying water on vine plants to save from frost, has to be
sprayed at a constant mist during each hour the frost lies at ground surface level, and incorporated with fans , such as windmill type fans, so
to keep at a constant temp. you are sorta on the money sfc. i've seen this done on grape, and blueberry crops around here, on a large scale.
i'll pass on that challenge hippy:eek: :) . i prefer this method...
 
I agree with all of you. They use the misting and fans for fruit crops in Florida. I just have a little 4 footer that I covered with the plastic bag as seen in the first post, held it up with stakes after the first night, and the plant is in mint condition. Now I am working with a week of good temps and have gained another week of growing. We will just take it 1 week at a time.
 

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