Frost- how sensitive to frost is cannabis?

The Southpaw · Sep 19, 2012

Cheers to all... have some outdoor plants, I am wondering where cannabis fits in the scale of frost hardiness? ( the ice type of frost)

anyone have any creative thoughts about getting the girls thru a chilly night? Know all about throwing a sheet over them,, interested in any other thoughts..

thanks and PEACE!

green-genes77 · Sep 19, 2012

Rather hardy, but it's dependent to a degree on the particular genetics in question. Light frosts are easily absorbed, even in small bunches. At the extreme end of things I've seen certain plants survive a 25 degree night and keep maturing after they shook off frost.

However, (and this is the kicker), it is not just a question of "how cold?" but also of "for how long?". Many plants will shake off an hour of temps in the mid 20s, but if the duration of those temps is much longer it will kill them.

If the forecast calls for temps in the 30s I wouldn't even sweat it unless it looks like it is cold for good in your area (check your almanac). Usually things will warm back up for a spell in October.

Frost protection falls into two categories: active and passive. Passive protections include anything done before a frost to minimize damage. These include cloching, erecting barriers, wetting and so forth. Active measures are intensive and include fans and heaters.

Before choosing frost defeating measures here are some things to consider:

Cold air moves along the ground like water. Plants in open low spots will be the first to suffer. Barriers can be useful in directing cold air.

Wind, clouds, and precipitation all protect against frost.

Dilute seaweed products have been indicated as useful for protecting against frost when applied directly on the plants.

Wet the soil thoroughly before frost is expected, or even water with warm water and place insulating mulches over the root zone.

Water releases a substantial amount of heat when it freezes. Tenting plants and housing large, shallow containers of water with them can moderate temperatures significantly.

If you believe your plants were subject to a severe frost, attempt to get to them before the sun hits them. By melting off the frost with water, you may be able to avoid cellular damage to the plant and possibly coax a little more maturation out of them.

mendo420 · Sep 20, 2012

If you can cover them it would be better.

They can take a frost.

My buddy told me he once washed icicles off plants with water.
I think hes full of it.

moondawg · Sep 20, 2012

A good hardy strain can brush off a frost and never skip a beat. Ive had plants survive 3 consecutive nights below freezing and i once survived 1/2" of snow!!!

Thats true of any hardy, vigorous strains but a finicky indoor strain, (diesils come to mind) isnt very hardy at all and my be harmed seriously by a hard frost.

SeaMaiden · Sep 20, 2012

I've tried to KILL my plants by leaving them out in the dead of winter. It didn't work. What did work was when June hit, not watering them. THEN they finally died.

These plants went out in November (this is from a few years ago, now I have the heart to straight up kill what I'm not going to use, back then I didn't). They lived outside under our black oak til the following June. They lived through frost, rain, snow, and a few hard freezes (down to 15*F). In 1gal pots.

Guest 315072 · Sep 20, 2012

ya gotta get good outdoor strains to have successful grows outside! i put stuff i grow indoors outside.. and it molded.. i put stuff out i flowered for 4 weeks then outside for a month and harvested.. and it was bomb bud.. it just all depends on the weather.. and strain.. i have been getting into the low 40s and my plants look fine.. still packing on the weight!

foomar · Sep 20, 2012

A couple of seeded MIS afghans stood the coldest winter for decades and two weeks below freezeing , retaining the seed till late march when a ring of dozens of new plants grew around it , then collapsed and rotted away.

Direct sunlight on a hard frosted leaf can turn to mush from cell rupture and kill it or allow in mould from the resultant damage , slowly defrosting in the shade seems to do no harm.

the gnome · Sep 20, 2012

frost shouldn't bother your plants,
In north florida ive started seedling trays in mid feb to be planted the last week of of march.
oout in the days to get the sun and in an unheated building at nite.
one nite i forgot to bring em in and came home at 1 am, they were 2 weeks old and covered with icy frost, stiff as a brick, took em in and they were fine the next days.
commercial crop growers in florida expecting freezes water the plants so they get a lite coating of ice on them, and that insulates them from the colder temps

also if your plants are in ground, roots are insulated and they fare better than potted plants.

The Iceman · Sep 20, 2012

Awesome post my friend! Awesome! I'm not the thread starter but thanks!

green-genes77 said:
Rather hardy, but it's dependent to a degree on the particular genetics in question. Light frosts are easily absorbed, even in small bunches. At the extreme end of things I've seen certain plants survive a 25 degree night and keep maturing after they shook off frost.

However, (and this is the kicker), it is not just a question of "how cold?" but also of "for how long?". Many plants will shake off an hour of temps in the mid 20s, but if the duration of those temps is much longer it will kill them.

If the forecast calls for temps in the 30s I wouldn't even sweat it unless it looks like it is cold for good in your area (check your almanac). Usually things will warm back up for a spell in October.

Frost protection falls into two categories: active and passive. Passive protections include anything done before a frost to minimize damage. These include cloching, erecting barriers, wetting and so forth. Active measures are intensive and include fans and heaters.

Before choosing frost defeating measures here are some things to consider:

Cold air moves along the ground like water. Plants in open low spots will be the first to suffer. Barriers can be useful in directing cold air.

Wind, clouds, and precipitation all protect against frost.

Dilute seaweed products have been indicated as useful for protecting against frost when applied directly on the plants.

Wet the soil thoroughly before frost is expected, or even water with warm water and place insulating mulches over the root zone.

Water releases a substantial amount of heat when it freezes. Tenting plants and housing large, shallow containers of water with them can moderate temperatures significantly.

If you believe your plants were subject to a severe frost, attempt to get to them before the sun hits them. By melting off the frost with water, you may be able to avoid cellular damage to the plant and possibly coax a little more maturation out of them.

The Southpaw · Sep 21, 2012

Great replies and advice, thanks to all. I had some aging freebie seeds, Haze 1 x Skunk 1 , ,, one popped,, and she is a great lanky thing...it will be interesting to see how far she gets...
peace!!

The Revolution · Oct 9, 2012

Im really worried about mine. I always assumed a couple nights of light frost would be fine aswell.. So ive left the majority of my outdoor garden to tough it out, as some are still weeks from finish.. Well tonights temps are right at 32-33 degrees. Theres a nice layer of frost out on my picnic table.. Im going to the garden first thing tomorrow morning.. Should I just harvest what i have now? how is the best way to go about this? Some are very near harvest, some need another couple weeks, and there's some even later sativa.. Durban, Zambians, Swazis, that may not be ready until end of Oct, or november.. I dont remember ever getting this cold of temps this early in the season. The last 2 seasons have both been like this. Frost, and freezing temps in early oct. Ruined many of my outdoor plants last season as I was out of town for weeks at a time and came back to dead plants, and dried out flowers on them.. Fuck this weather has ruined my season.. All of that hard work down the drain.

The Revolution · Oct 9, 2012

How would you suggest melting off the frost with water? Would you use a sprayer ? Warm or cold water?

green-genes77 said:
Rather hardy, but it's dependent to a degree on the particular genetics in question. Light frosts are easily absorbed, even in small bunches. At the extreme end of things I've seen certain plants survive a 25 degree night and keep maturing after they shook off frost.

However, (and this is the kicker), it is not just a question of "how cold?" but also of "for how long?". Many plants will shake off an hour of temps in the mid 20s, but if the duration of those temps is much longer it will kill them.

If the forecast calls for temps in the 30s I wouldn't even sweat it unless it looks like it is cold for good in your area (check your almanac). Usually things will warm back up for a spell in October.

Frost protection falls into two categories: active and passive. Passive protections include anything done before a frost to minimize damage. These include cloching, erecting barriers, wetting and so forth. Active measures are intensive and include fans and heaters.

Before choosing frost defeating measures here are some things to consider:

Cold air moves along the ground like water. Plants in open low spots will be the first to suffer. Barriers can be useful in directing cold air.

Wind, clouds, and precipitation all protect against frost.

Dilute seaweed products have been indicated as useful for protecting against frost when applied directly on the plants.

Wet the soil thoroughly before frost is expected, or even water with warm water and place insulating mulches over the root zone.

Water releases a substantial amount of heat when it freezes. Tenting plants and housing large, shallow containers of water with them can moderate temperatures significantly.

If you believe your plants were subject to a severe frost, attempt to get to them before the sun hits them. By melting off the frost with water, you may be able to avoid cellular damage to the plant and possibly coax a little more maturation out of them.

The Revolution · Oct 9, 2012

I went out today and harvested some of the flowers. It def froze last night, and some of the potted plants I doubt with be able to continue. I was forced to harvest most all the potted plants, but some of the others look like they may be able to pull thru. I stayed out long enough to watch the ice melt away from the flowers, and see them start to thaw out. They remained green, and looked just as good as they did before the freeze. Im hoping they are able to continue for another week or two, and mature a bit more before I harvest the bulk of the gardens. Wish me luck

GrowersUnite · Oct 9, 2012

two days in a row of frost, last night hit 32 with real feel of 36 before i went to bed. woke up to nice layer of frost everywhere.

did a quick peek, and the tops still look green. I'm gonna water with molasses/water today and I'll really look this time.

all my plants are potted.

The Revolution · Oct 9, 2012

Best of luck to ya man. The Humidity last night was 90%. Looked like there was a bit of moisture on the plants before they froze, which may have actually helped to shield them.. Keep us updated. It will be atleast a week or 2 before Im able to go back to the gardens to see how theyre doing. Im praying the weather will stay above freezing, and the plants can pull through and finish up for me. I have a couple pounds on the line drying now, but theres 2-3X as much weight still out there..

seaweed · Oct 9, 2012

If you keep the leaves form freezing it can go deep frost. The ground will still stay warm enough. Problem is if it is cold for days with no let up then your screwed.

.clunk · Oct 11, 2012

seaweed said:
If you keep the leaves form freezing it can go deep frost. The ground will still stay warm enough. Problem is if it is cold for days with no let up then your screwed.

I've found that not all leaves are affected by a deep frost, but any necrotic or very yellow leaves seem very prone to frost damage and wilting when the sun hits which would probably lead to mold.

I have 5 ladies left outside which have been seeing freezing temps at night for the past 10-12 days or so; I've had to pick off some dead and dying fan leaves since the frost started but the plants are positively shimmering with resins, it's quite an amazing sight actually. Buds have been getting denser, though not bigger, for the past week or so.

The Southpaw · Oct 13, 2012

My very sativa girls made it thru 2 light frosts with a few burnt leaves but with the daily temp avg being so low I don't anticipate much more growth, and since it's a hard freeze tonight I cut most and brought it in..they could have gone longer but I am satisfied so far .. I have a runt haze that I am going to leave a bit longer as an experiment..

Back to trimming :dance013:

ItsTopShelf · Oct 14, 2012

southpaw .. lol u got afuck it plant also? lol ya i just honestly didnt wana smoke or waste time trimming something thats not even close to dun.. it was a seed found in a plant of hazex skunk so i think its a haze sativa plant its no were near done so im going to see wen it dies lol.. i understand that the frosts destroy trichs so it causes damage .. but i wana see wen would they die.. around what date .. and after how many frosts if just left there not watering.. no nothing

HOPS5K · Sep 20, 2013

I know this thread is old, but it's helpful.

temps are supposed to be in the 30's tonight...got 3 girls outdoors about 3 weeks into flowering..seem to be doing fine, but it's getting noticably cooler.

I'm thinking of covering them, but I read earlier in this thread that they can take 30 degree temps.

Frost- how sensitive to frost is cannabis?

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