Preventing mold/mildew in a SCROG?

Hey RIU!

I'm a little over 4 weeks into flower in my first SCROG grow, so far everything is looking great! However I am quite concerned about eventual mold/mildew problems. The temps are constantly between 72-80 all day every day, humidity is usually in the 30-40% range, sometimes going down to 20 and other times going up to 50%. I have two 4x4.5ft screens that are currently filled completely, each screen has six plants underneath it. Two rows of 3 plants. My main problem with this set up is that I'm only able to get under the screen to trim the first three plants in front of me, but due to a lack of space I have no way of trimming the three plants in the back row.

Anyway, my question to all of you SCROG experts is what do you all do to prevent mold/mildew in your grow? Obviously it wouldn't take much time at all for it to ruin an entire screen and I want to do every and anything in my power to prevent this from happening. I have tons of air circulation in the room, the AC is in the middle of the room blowing 24/7. I also have 2 fans underneath each of the screens for a total of 4 fans underneath the canopy, always oscillating of course. I also have two oscillating fans on each ends of the rooms blowing air above the canopy as well as a 720CFM fan that recirculates the air in my grow room. So it seems like I have the ventilation part under control, however not being able to clear out the undersides of some of my plants is really concerning me because I know that's going to cause me problems eventually seeing as how mold loves dead plant material.

Are there any other ways to prevent mold/mildew other than removing branches and the like? I'm concerned because I'm in week 4 of flower and I'm afraid that if I do too much trimming that I'll stress out my girls. How much of the plant can I trim away before it gets too stressed out? Are there any other methods of preventing mold and mildew that I can incorporate into my grow? Because with how full my screen is I'm already concerned about the buds touching each other as it looks like there are a lot of buds that will be touching in about 2-3 weeks or so. I really don't want to lose my crop to mold or mildew and due to me growing with the SCROG method I'm able to see just how much easier it is for mold/mildew/mites to take control compared to other methods of growing. Any and all help from anyone would be greatly appreciated, as always!

The best thing you can do is the thing that you can't/won't do. Pruning lower branches and removing large fan leaves to open up the plants will prevent pockets of high humidity and stagnant air. Large colas are often easy targets for botrytis. Keep larger floral clusters from touching one another and inspect often for signs of mold.

Good air flow, not overwatering or allowing runoff to sit, low humidity, clean area (no dead leaves or other organic matter lying around) and possibly a treatment with a product like Serenade.

The lower shaded branches will not produce quality buds. Pruning will not harm the plant.

I guess you should ask yourself if you'd you rather stress the plant a bit or end up with a botrytis outbreak that destroys the entire crop?

MYOB said:

The best thing you can do is the thing that you can't/won't do. Pruning lower branches and removing large fan leaves to open up the plants will prevent pockets of high humidity and stagnant air. Large colas are often easy targets for botrytis. Keep larger floral clusters from touching one another and inspect often for signs of mold.

Good air flow, not overwatering or allowing runoff to sit, low humidity, clean area (no dead leaves or other organic matter lying around) and possibly a treatment with a product like Serenade.

The lower shaded branches will not produce quality buds. Pruning will not harm the plant.

I guess you should ask yourself if you'd you rather stress the plant a bit or end up with a botrytis outbreak that destroys the entire crop?

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Don't get me wrong, it's not that I won't do it. I've been doing my best with the ones in front but the ones in back are almost impossible to get to without destroying the screen or moving the plants around so I'm kind of stuck. But are you sure removing branches and the like won't stress the plant out? I remember I did it to a plant and it's yield suffered compared to the others and I figured it was because I trimmed too much. I guess the best solution is to just do smallish amounts so as not to stress the plant. However thank you for putting it in a different perspective for me. You're 100% correct, it IS better to stress the plants than to have mold get in the room. Mold in a grow room is bad enough, but when you have a scrog to help it along? :/

Thanks for your advice, I'm gonna get to trimming now since the girls just woke up

Fan blowing across the under side of the canopy.
Air Flow under canopy and above the canopy. Will helps reduce chance of mold in a SCROG.

With those humidity levels your chances of mold are already at a minimum even without decent air circulation, but since you have plenty of circulation you shouldn't have any problem. Another way to keep the plant from getting any mold is to remove all dead leaves and clean any leaves that have fallen from the surface of the soil.

i always have ductwork blowing fresh air under plants this greatly reduces the risk and helps oxygen get to roots in hydro setup.

budskey said:

i always have ductwork blowing fresh air under plants this greatly reduces the risk and helps oxygen get to roots in hydro setup.

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Well hopefully you'll be happy to know that I actually have that as a factor in my grow room as well! Turns out there's a hole in the floor of my grow room that used to be a part of the central AC, instead I attached some ducting to said hole and my inline fan is so powerful that it's actually pulling the air from that hole into the grow room as it exhausts the hot used air.

Turns out I just needed a little nudge, I got under there and managed to remove the dead material as well as a few branches. I couldn't do everything I wanted to, but the difference is so obvious. I can already see the amount of room I've created down there for the fresh air to blow through and I'm so excited at how much better things look now.

Thank you all so much for your input, again I can't thank you enough. I've learned so much from this forum and so far this current grow is looking like it will be a 100% success, everything is perfect. I knew that ventilation underneath the canopy was crucial, however I had no idea about the dead material being a perfect environment for mold! In all the research I've done I've never seen this mentioned so to all of you that brought this up, thanks for the knowledge I'm glad to know my humidity levels are proper as well, sounds like now that I did some pruning everything is under control.

I'd like to thank MYOB again for his insightful perspective on the situation. Realistically the plants will be stressed for 3-5 days at the MOST. This short period of time of stress is a godsend compared to what mold/mildew would do to my grow! So thanks again for the perspective! All of your advice helped greatly and thanks for all of the help again.