Raising the Humidity in my Grow Room

I have a Yield Lab 2x4x5 foot with 423 watt LED grow light and 2 - 6 inch fans circulating the air. I have a 4 inch vent fan attached to a carbon filter hanging in the tent that I use sparingly as it lowers the RH. I am maintaining the temp at 85 daytime and 65-70 at night. I am using Miracle Gro 24-8-16 that I have always used and had good luck with. My soil is potting soil with a biologic added for the microbes. I have not added anything other than water and fertilizer. I keep the soil well watered +/_ 200-400 ml daily. The problem is raising the RH to over 50%. I spray in the morning and even have two large cups of water in the room. I still cannot get the RH to raise. I have two White Widows and one AK-47 in day 10 of veg and the book says that I need to keep the RH higher. Can you think of anything else I can do? Thanks

Look for actual humidifiers. You can probably pick one up at a thrift store dirt cheap, but even new I think you can find them for around $20 at a walmart or some place similar. If it doesn’t have it’s own timer you could try attaching it to a simple light timer and get it turn on and off periodically to get your humidity where you want it.

Should have thought of that . . . sounds like the good step. Thanks for the input. On it today!

Definitely the way to go :slight_smile:

I went a little lower tech (also less money) and used a 10" x 5" x 6" deep pan of water in the tent. RH is rockin’ in at 70% at night. Have to watch the RH as the fan circulates to water vapor OUT of the tent. Seems to be working so far. Plants look healthier now. Am going to get a humidifier when I get the extra.

There is really a large learning curve with growing MMJ. I used to just throw seeds into soil and water. I think I messed up by trying to use more fertilizer than needed. Cleared up all my above problems but now one of my widows is turning light green/yellowish and the end tips of the leaves are curling up and dying. Got pictures for you. It looks like a nitrogen deficiency but I have been giving a mixture that seemed to work previously. I am currently on Veg day 15 with two WW and one AK-47. Only one WW is effected, the other Widow and the AK are doing great.

My nutrient combo is: Alaska fish fertilizer 5-1-1 5ml/gal, General Hydro Flora Micro 5.0-1 7ml/gal, Humboldt Deuce-Deuce 0-0-22 2ml/gal and Humboldt Honey 0-0-1 3ml/gal. I give this to the plants every three or four days when they need fluids. It was doing good until 2 days ago when the leaves started turning light green in the inner spaces between the veins and the veins remained green. It is only on the lowest family of leaves and I do not want to have it move up the plant which makes me believe it is a mobile nutrient and works from bottom to top. All of the upper stems have started to turn purple.

I checked the pH in all three containers. They were all between 6.5 and 7. The sick one is at 7. The pH seems in balance from what I have read.

In addition to the list of things that I have in my grow room, I added a CO2 producing bag yesterday. I also have all lights and fans on timer for 18/6 now but am on Veg day 15 and would like to start flowering. Should I proceed with flowering or resolve this problem first. I was thinking resolve first.

I am going to try to load the pictures so you can see. The plants have good branching and I am hoping to get ready to flower soon. I want to keep them short (my tent is only 5 feet tall) and hope I can keep them short enough. Here is my sick Widow.

This is my “Widow Next Door” that is doing well.

The pictures did not come out as good as I would have liked, I hope you can see the color change and the brown tips, and their absence on the second one. .

If I need to give more info, please let me know. Thanks.


pH can range, and 7 in some grows will not show problems, but you are pushing it with a pH of 7. If your meter isn’t accurate enough to measure to the tenths, and always rounds to a point 5 or point zero, it is probably safer to err slightly under 6.5, and shoot for between 6.0 and 6.5, rather than shooting for between 6.5 and 7.0

Another thought, if you are using tap water or mineral water, you may have an excess of calcium carbonate, contributing to the high pH. Purple stems can be a sign of a cal-mag deficiency, but in your case I think it is the magnesium being locked out from the pH. Adding some epsom salts, i.e. magnesium sulfate may make your plants tolerate a pH near 7, but you still want to keep it as close to 6.5 as possible in most cases in soil.

Hi MacGuyverStoner,

I used your recommendations of Epsom salts and it helped a little. I also flooded it with distilled water before and I bought some Humic Acid that is supposed to make the pH drop. I gave it some 8% Humic Acid (5 ml) in a gallon of water and watered the ailing lady. The next day she appeared to be starting to perk up a little and is now turning the leaves a little better shade. I also added a touch of Cal/Mg+ and this evening it looks like it has turned the corner and is going to do better. Looks like the Epsom salts and Humic Acid may have helped the cause. I am trying to use only rainwater now also. We do have a lot of salty residue on the faucets in the bathrooms and shower.

I am going to try to reduce the amount of organics I add until I get a little experience. A friend of mine from high school just looks at a plant and knows what to do instantly. Guess it really helps growing constantly from High School to now. Wish he lived next door to me like in high school. He has been making a living growing since 1973 when we graduated and has never had a real (9-5) job and just lives as he pleases out in the country. He has several degrees in Chemistry and Biology to help him out.

Thanks for the help getting me out of the situation. This is definitely a learning process. I have learned a lot just from studying since your last advise.