How To Deal With Cold, Rainy And Humid Weather

The marijuana plant can be a very flexible plant and can grow in extreme weather, but this can cause abnormalities and growth problems. Keep on reading to find out how to solve weather problems and how to protect you marijuana plants.

Cold spells

Cold spells cannabis

Problem: The weather report indicates an upcoming cold spell that could drop below freezing with warmer weather expected by the end of the month. How do I prepare my garden for the cold?

Solution: As defeatist as it might sound, your primary job is to keep the plants alive until the weather takes a turn for the better. At 45*F (7*C) most plants stand a good chance of surviving unscathed. When better weather comes back, the plants will effectively restart the growing process.

If you can bring the plants inside and give them a moderate light-on cycle, then they will be sustained for a while until the weather changes.

Patio heaters can be put in the garden and could ward off frostbite in the plants. You can also construct a temporary greenhouse with a wood frame and plastic coverings that will trap the heat more efficiently and can be taken down with the arrival of better weather.

Polyethylene can be used to wrap individual plants. This will not only protect the plants from wind and rain, it will also preserve some heat. Still, the cold will eventually makes its way to the plants unless you’ve provided them with some source of heat. Forced air heaters might be ideal to heat the plants. Be sure to set the gauge at 70*F (21*C) to avoid overheating.

Cool weather

Patio heater for cool weather

Problem: The plants are not yet mature, and the weather is getting cooler. How long can the plants stay outside?

Solution: As daylight temperatures descend to the low 60’s (15-18*C), plant growth will start to slow dramatically until it basically stop in the mid-50’s (12-14*C). If you don’t think that the daylight temperature will consistently get above the high 60’s (above 20*C) then you might think about scrapping the crop.

Evening temperatures might be descending into dangerous territory. Indeed, most plants can endure temperatures that drop into the 40’s (5-10*C), but when it drops anywhere below that (under 4*C), tissue damage will be prevalent.

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Any solution really relies on the amount of available sunlight. As the Earth shifts seasons from autumn to winter, sunlight intensity and overall longevity will decrease. Plants that might have been in full light in the summer and early autumn are now shaded for most of the day. Clouds might also decrease the quality of the sunlight. In the winter, the plants are not allowed adequate light energy and should be harvested to avoid a wasted crop. Even if the buds are not ripe enough to smoke, they can at least be processed for kief, extracts, or for cooking.

If the weather is cold but the plants are still receiving adequate sunlight, they could be placed behind a clear piece of plastic. This will almost have a greenhouse effect by trapping the sun’s heat and promoting growth in the process.

You could also use items called “passive heaters.” You really just have to fill up some dark-colored containers with water, let them heat up during the day, and then they will radiate heat at night.

Propane-powered patio heaters will also keep the plants warm. They’ll also burn gas that produces CO2 and water vapor. The added CO2 will promote growth.

Humid weather

Humid weather cannabis

Problem: The weather is turning humid and moist.

Solution: Start harvesting any and all mature buds. Then, spray the remaining plants with anti-fungals. Try to keep the plants as warm as you can. If humid weather is commonplace while the plants are ripening, you might try different varieties with looser, drier buds.

Rainy weather

Rainy weather cannabis

Problem: Rainy weather is in the forecast. How can the plants be protected?

Solution: Mold abounds in rainy weather because water slips into the buds and creates ideal conditions for molds like Botrytis to thrive. The buds tend to hold and hide the water and humidity in their crevices and it can prove difficult to dry them out.

If you can move the plants or construct an enclosure, then rain will not affect the plants, but moisture still might. Increasing temperatures in the enclosed area (up to the 70’s F or 24-26*C) could protect the plants and help dry out the buds because mold growth would be curbed. Circulating the hot air with a fan certainly helps.

If rain is forecasted as a brief, one-time occurrence followed by a continuation of warm, dry weather, then you can protect the plants by treating them with an anti-fungal like potassium bicarbonate or Serenade prior to the rain. If prolonged rain is expected, then you might just think about harvesting the plants right then instead of having them just turn into mush.


Wilting cannabis

Problem: Wilting appears out of nowhere. One second the plants are beautiful and thriving and then a few minutes later they start wilting.

Solutions: These plants tend to draw up water by maintaining a higher salt concentration within their tissues than in the surrounding soil. In the event that the salts (fertilizer nutrients) become more prevalent in the planting mix than in the plant itself, then that usually suggests that the plant can’t draw up water or it, in fact, just drains from the plant. To fix this, try flushing the soil with pH-adjusted water at 72*F (22*C). The amount of water should be equal to about 1.5 times the volume of the container (e.g. 7 gallons to flush a five-gallon container).

Occasionally, cannabis leaves will droop at the very end of the light period. This is normal and should not cause any worry.

If you order marijuana seeds from my webshop and you get problems with your marijuana plants, I’m here to help you. There are guides about plant care where all problems are discussed and you can contact me by mail. Please like or share this article


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Robert Bergman


Robert Bergman is an Amsterdam-based marijuana grow expert who has years of experience from small grows to massive operations ... See profile

13 comments on “How To Deal With Cold, Rainy And Humid Weather”

  1. I am looking for advice on outdoor growing in the subtropical South, where it’s hot and hi humid and it rains for at least part of every day in the summer. And autumn gets occasionally hurricaney, lol. I looked at your guide on jamaican rasta life but it was cultural and had very little info on how and what is grown there. Given that this climate resembles Jamaica more than the rest of the states, what grow advice could you give? What strains are grown in Jamaica? It would need to be mold and mildew resistant and heat tolerant (most days are over 90⁰F). Also the insects here are ferocious because there is never a freeze to kill or limit them, so add heat-resistant to that list. It makes the prospect of an outdoor grow here very daunting. But citrus grows well, so it can’t be that bad. Any advice for the swampy South?

  2. You can commune with your plants and they will talk to you and tell you what they need. You just have to listen <3

  3. I am a second year grower in Southern Maine. I came to growing with over 20 years experience with other plants which gave me lots of knowledge that could be transferred to growing Cannabis. I pile plants in the greenhouse when it gets cold and they seem to keep each other warm very nicely. When it gets really cold I use a heater as well and use fans for circulation. For the plants in advanced stages I don’t move them but I have found that covering them with high thread count bed sheets (top sheets) is very effective to help outdoor plants retain their heat. Lay them loosely over the plants and keep the plants fairly close together. The high thread count weave is tight enough to prevent heat loss. These sheets are expensive so I only recommend this method if you happen to have the sheets lying around. It gets very cold very early where I am in Maine. We have nights getting down into the thirties this year in late August, early September. The days still get well above the sixties though so it’s all good. These cold dips are great at reducing spiders and mites. I recommend checking your plants several times a day. If mold is present you can very lightly trim this mold off if you check the plants every day and keep a very close eye on them. You just have to slow down and take your time with your plants. I have many varieties this year (sex, gorilla glue, J blue, Kush, blue, and big baby). So far, so good. I have no indoor set up and grow a very large crop each year. I love my hobby. It’s good for my soul : )

  4. It gets cold here in Oregon towards the end of budding season – late September and into the October. I like to force flower half my crop, finishing them during July and August, then let the other couple plants finish naturally, in case they get ruined by inclement weather. This year I’m covering the plants that finish naturally, to protect them from rain, wind, and cold. Rain and wind will rip branches off, if you don’t support them somehow. I want to put in a greenhouse, at least a hoop house, but that costs money I don’t have. Any ideas for an inexpensive design for covering my plants would be appreciated. I’m leaning towards a do it myself hoop house, or building a frame with wood. My dream is to have a geodesic dome for each plant, BIG domes!

  5. The trick is to check them everyday at least 4times a day. Love them and get the most out of the cold months!!! Summer is the easy part,keep your room clean,and watch for spider mites!and other pests!or disease! Peace out man!

  6. Hey there bud, I’ve been growing in upstate NY for almost 2years now. I’ve learned allot. I have an old 1car garage I’ve insulated and heat with a small propane heater. I have 4 strains going,purple haze (my first plants), Acapulco gold, crazy miss Hyde, and OG kush. All females 3from seedlings and the purp was!cloned. I have a rotating crop. I clone them all. Some advice for growing up here where it gets cold for a long time. Below 50°f the whole process slows!way up! That means less watering and more creating in the veg stage to get the most out of spring and summer! Last winter……forget it,it was to cold, this year so far so good. The advantage; less pests, less watering,but slower flowering and harvest during winter months.I love your site, how do you ship your s3ds? And do you back your product? I’d love to keep your readers posted on my current crop. Last year a hard lesson was learned,man my plants froze so hard they stuck strait out,lol now it’s kinda funny, then it wasn’t, I lost 22plants of which 4/were almost done flowering!(soggy,black buds)lol I still smoked what I could save!

  7. […] Excessively rainy or humid weather also causes issues. Foremost, they will leave plants extremely vulnerable to fungus and mold, so try to make sure your plants get dry and warm after periods of cold rain. Of course, storms can also cause direct physical damage to your plants. There’s little you can do about this if you are growing your plants outdoors. Learn how to deal with cold, rainy and humid weather. […]