Humidity help?

Discussion in 'Growing Marijuana Indoors' started by Be Water, Jan 31, 2023.

  1. Hey all! Quick and dumb question but anyone have any idea what the hell I'm doing wrong?

    I can't get my grow room above 43% RH even though my grow room is 350 sq feet and I have TWO humidifiers in there that are supposed to humidify a room that's 350 sq feet EACH. Yes, I live in Colorado, where it's dryer, but the humidity here has been in the 50s and 60s lately. My grow room is very well insulated but how am I not able to get RH over 43? I've tried putting the humidifiers right in front of my oscillating fan that blows on the plants. I've tried putting the humidifiers in the center of the room. I've put them on the floor. I've put them on buckets to raise them. Still, can't get over 43 RH in Veg. Anyone have any tips to get higher RH using these humidifiers? Thanks!
  2. are you surrounded by concrete floors and walls that are sucking all that moisture up?

    Have you tried dumping a gallon or two of water on the ground. lol
    • Winner Winner x 1
  4. Air exchange.......,.............
  5. Care to elaborate? I have air coming in. No air going out. If I have air going our how does that help raise the humidity? Thx!
  6. Take up plastic and soak floor for added humidity, you need to exhaust / exchange incoming air.
    Keeping it fresh . Have air exchange periodically come on according to your humidity needs.
    Use an inkbird humidity meter or outlet timer. :thumbsup:
  7. Make sure that whatever you are using to measure RH is working and accurate.
    • Like Like x 1
  8. I was going to suggest getting a new hygrometer, but this is a good idea.

    What are temps in the room and how are you controlling temp in the space?

    I have no affiliation with them, but I bought the HT1, and have used it for at least 3 years. Really slick.
  9. So you're creating a postive pressure environment? In with no out=positive pressure, now the main question......what does positive pressure do to VPD?
  10. THIS!
  11. May i ask why your even concerned about the humidity ? You can clone veg flower in 10 %. In flower its better about 30 to 45 % max yields . Clone veg they really could care less . Show me a vegging plant picture that is too dry from lack of humidity . Now i have to say unless a grower is pumping max par of light and pumping killer amount of nutrients then its possible the plants humidity is too low . So raise the lighting a bit why pump shit loads in veg ? And why feed shit loads in veg ? So if dont correctly humidity really does not matter , My opinion . And as a poster said above water the floor . Get a mister spray vegging plants .
    Bring the wife into the grow room pleasure her !!! Depending that could raise the humidity as well if you know what im saying . Yeah water falls
    • Agree Agree x 1
  12. Temp with small heater on? 78 degrees. Temp with it off? 71. I just bought two brand new hygrometers. I admit. They're not expensive BUT got good reviews from growers AND they're both reading the same temp and humidity. I'd think one of them might be inaccurate but TWO? I guess anything possible so I'm trying the salt method as explained above. I'll post results here.
    • Like Like x 1
  13. You can also get some salt. Put rock salt in a bucket. That salt will suck all the water into the room
  14. May i ask why your even concerned about the humidity?
    Sure! Mostly because every write up I've read, every video I've watch, and every grower I've talked to has told me that vegging plants like it better when they get higher humidity in veg. Why? To try and reduce transpiration through the leaves thereby taking some pressure of the maturing root system. Dumb advice? Maybe. It's just what I've been taught. For example, this VPD chart. Could this all be nonsense? Sure! But you asked so I'm telling you that's why I care about humidity. I'm in week 3 of veg with temps around 78 degrees in the grow room with some cool fresh air coming in but no exhaust. I can exhaust easily, just am choosing not to at this time.

    Show me a vegging plant picture that is too dry from lack of humidity........
    All I can say is I could go into my grow room with you and show you I have vegging plants that look pretty decent but a bunch of them are "tacoing" and it's NOT due to heat stress I can promise you that. I've done three grows in a row with "Apple Fritters" strain and my humidity is always in the 30's or low 40s with temps between 71-78 and some of the plants seem to want to taco. Maybe that's just a characteristic of "Apple Fritters" but the grow room environment is just about perfect except the RH. (and positive pressure if that has an effect) I THINK the tacoing is from lack of humidity but again, I could be wrong.

    And as a poster said above water the floor . Get a mister spray vegging plants .
    I'm not going to water the floor but will mist the plants. To much of a pain in my ass to untape all the plastic on the floor and then put it all back.

    So raise the lighting a bit why pump shit loads in veg?
    ONLY because I worry about them stretching

    Bring the wife into the grow room pleasure her !!! Depending that could raise the humidity as well if you know what im saying
    This is easily the best grow advice I've ever gotten on any level. Thx!

  15. Toss that VPD chart out the window man. Im 100% on board with the other guy. Lower humidity = more transpiration. More transpiration = the rots sucking up more water and more nutrients. Sucking up more water and more nutrients = bigger better plants. Ive grown at a pretty wide humidity range. As long as your roots and plants are healthy, they love low humidity. Best way to get healthy roots - force the plant to use them. I shoot to keep my humidity 20-30%. Temps under 75. Super low humidity and high temps might eventually cause a problem.
  16. VPD affects plant growth by determining the rate at which water evaporates from the leaves and enters the air. If the VPD is too low, the plant may not be able to transpire (lose water through its leaves) enough to take up the water and nutrients it needs for growth. If the VPD is too high, the plant transpires too quickly and may become stressed as it loses water faster than it can take it up.

    This can lead to wilting, stunted growth, and reduced yields. In general, plants grow best at a VPD that is neither too low nor too high, but provides a balance between the plant's need for water and the availability of moisture in the air.
    • Agree Agree x 1
  17. Yes indeed great answer . I never seen an issue in our rooms with humidity . I have seen it down to 10 % before and we used to use all metal halide . Air was so thin lack of any water i swear you would get nose bleeds how it felt . But again we had it all dialed in with nutrients and the lighting was perfect . Under these new led lights yes i could see a serious issue somebody cooking there plants . They do perspire under these new led lights . Mainly the par is to high causing them to try to survive the extreme stressful light . My experience only . Yes humidity does matter if your pushing things to a limit or to high . 'Honestly i never seen much or a veg speed difference forcing huge amounts of light vs less as in the proper amount . More light in my situation would stress the plants for sure . A grower could force many ppm of nutrient into the plant and crank 1500 par and add co2 to speed the veg up a couple days . Not worth it here.
  18. Love it. You guys rock. Thanks!

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