Tan color growth on soil and grow bag

8 days ago I transplanted 3 clones a friend gave me into 5 gal. grow bags using FF Ocean Forest.
I noticed some tan color growth on the surface of the soil and on the side of one of the grow bags.
I live on the coast of Maine,USA where it rarely gets very hot or humid and mold is rarely a problem so not sure what this is.

I’m sure someone more knowledgeable will chime in, :eyes: looks like a moisture/mildew/mold issue, how’s the ventilation in there?

Ventilation is fine. I have two WW in my grow box that are just starting week 6 of flower stage. These three clones are on a window seat in my living room until the harvest. Humidity is low there.

Here’s a pic of the clones.

I think @Momtomask is in your area. They may know. Or maybe @garrigan62 may know

I would say mold or mildew look like what I had 1 part peroxide to 4 part water sprayed on the pots a few times should do the trick if you want I can tag you in the part of my journal where I was showing it

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Im really not sure. But if I were you. I would get them out of thoughts pots and get them into better soil. If you do that and you really should mix up in a gal of water, 2 or 3 cap full of hydrogen peroxide, 2 mil liquid thrive and 2 mil of root stimulant and water them real good and it will help your plants with any shock they may have when you transplant.


The soil I 'm using is Fox Farm Ocean Forrest which has never had this problem before. Got up a little while ago and the color has turned from tan to white. Dying or just changing color? Not sure if that’s good or bad. Thinking about trying to clean it up by scraping off or maybe sucking it up with my shop vac and see what happens.

Thank you. Last night it changed in color from tan to white. I was thinking about scraping it up or maybe sucking it up with my shop vac and seeing if it comes back but I could also do the peroxide mix spray.


I like the idea of spraying with a peroxide solution. That should kill it off I think and it wont hurt your plants

Well give it a shot with the peroxide and see what happens.
Please keep us posted on the results…ok


Nuke it from oribit. Only way to be sure.

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Will do. I cleaned off any on the side of the grow bag and the top soil layer with my shop vac and will use the peroxide mix when my friend gets back from the store with it. She suggested that maybe I was using to much water since they were recently transplanted and don’t have much of a root system yet. I was giving them two cups each every two days.

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Not a bad idea but the drop ship just crashed so now what?

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Game over, man. :wink:

Well I wouldn’t blame it on over watering not with 2 cups every couple days.

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I am going to say mildew… you have them in a window seat. I am guessing gets direct sun for a short while then reflective sun the rest of the day. You have been keeping the soil very moist and the light is low. I would say the mildew spores are either inside your home in another house plant, or were growing a top a opened bag of soil you used for the last grow.

Did you place the bag outside in a shed or an area that is dark and moist? Was this the first clone you planted of the three and got the first scoops of soil from the bag? It’s also a possibility that the clone picked it up from its original location before coming to you.

Clones can have many perks, but you risk bringing home unwanted issues as well…

Remember small plants or root systems require small amounts of water in mild temperature growing conditions. You have them in bags pick them up and feel how heavy they are with water in them. Then feel them everyday as they get lighter the water is being used up. When they feel much lighter that is when they need more water.

Also no need to get the whole bag wet. Just keep it around where the plants roots are when they are young and it limits issues. As they grow then you can increase the area you are getting wet in the bags.

Thank you. You might be correct. They are in a spot that only gets direct sun for a relatively short period of time. What a friend gave me were 6 clones. 2 Bergman Gold leaf,2 silver haze,and two super skunk. They were in rock wool that had been placed in small pots with a small amount of FF Ocean Forrest. They were kept under a humidity dome until I thought they were ready for transplant. I used new 5 gal. grow bags filled with new FF OC. The first three showed no visible roots when I transplanted them. I did the next three a week later and they all showed visible roots. There was no sign of the tan growth prior to transplant. Right now they all look good and are growing. I’ve topped two and will be topping the rest soon and plan to keep doing that to control height until my grow cabinet is free. There are two flowering WW’s in there now with about 3 weeks to go to harvest.

As to the tan growth,I cleaned that up in the three that showed it and hopefully I got it all. I’m going to move them around some to different spots so they will get a little more direct sunlight. For what it’s worth the tan growth turned white after dark and then went back to tan once back in the light. This is what they look like this morning.

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Fox farms has a lot of salt buildup most all my pots that where fox farm ocean all have salt stains Not sure if that’s what’s going on but very Possible


Just curious about how often you had to spray before it was gone. I had sucked it up with a shop vac two days ago and then sprayed the areas affected. Today it was back but I also learned today that hydrogen peroxide has a short shelf life so I likely just sprayed them with water the first time around. Bought some fresh today and sprayed the soil and any growth on the sides of the pot so will see what happens.