First grow Rust Spots

I have 2 ilgm gelato autos in 5 gallon fabric pots with Sohum Living Soil water only. Using filtered tap water ph’d to 6 to 6.5ish. Popped from soil on Feb 6th, so this is week 6. 70 degrees with 40 to 50ish humidity. Light is Mars Hydro ts1000 at 12" 75%

Today I noticed some rust spots forming. They are on leaves midway up the plant. It is mostly 1 plant, however the plant with fewer signs is a week younger. I have some red petioles and stems as well and new growth seems to stay lighter green, but seems healthy to my very untrained eye. My main concern is the spots. I’ve looked around quite a bit and I’m thinking it could be calcium, magnesium, and/or sulfur. But I don’t want to randomly start throwing chemicals at it without confirmation. I’ve checked to see if it’s mold, but it doesn’t leave a residue. I do not see any pests in the tent or on the leaves. I have Epsom Salt on hand (Have not used.)

Any thoughts on what this might be? I appreciate any help, I know you guys have quite a bit more experience than I do.

Thank you.


I’ve seen this before. Those spots are most likely a calcium deficiency. I grow in soil with ro water and mine do that if I don’t and calcium. My soil is loaded with magnesium. Calcium is usually the limiting factor in living soil. I grow organic so I add about 3-5 tbs. Of gypsum per gallon of my ro water and it stops. Later in flower I cut the calcium totally and switch to epsom salt. I am about to harvest some fat nugs but I freaked a bit when I saw what you are seeing. Bump the calcium a bit and you’ll be good. Red stems that are exposed to light is normal. Streaks in the stems is often normal. If the stems go all dark purp you have a lockout and your plant will look pretty rough. These are looking good. How often do you water and how much?

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Thank you. I will pick up a calcium supplement in the morning.

For watering, I have them on AC Infinity wicking bases for bottom watering, but I also add about a quart of water to each from the top every 3 days to keep the top layers of soil from drying out and damaging the soil microbes. They seem happy with that so far.


Awesome. Check out build-a-soil on YouTube best damn docu series on living soil indoor grows. It is the best info available. Too much info on growing mixes hydro and other inert media with soil and it’s not right. There are a bunch of ways to grow this plant and much of the info you read or will be told here by “experts” is wrong. I’ll give you and example. If you are growing in living soil inoculated with microbes you don’t need to ph your water at all. The microbes will buffer things to exacty what the plant needs when it needs it. You just need to make sure your soil has the building blocs avail and the bacterial and fungal colonies to break them down and make them plant avail. Throw away the ph pen and the up and down chems. If the ph is between 5 and 9 you are good to go. No need for ph meters or ppm pens. It’s better to know what is actualy in your filtered tap water than what the ph is when growing in soil. Could be full of salts and other garbage. Go with ro water or get a water test done so you know if there is anything in the tap water that could cause issues. I tried growing in living soil and meticulously phd my water and I had deficiencies, Droopy/speed bump leaves with spots. and all that. My tap water filtered is like 600 ppm of who knows what and that is a big prob for me and why I have to use ro. Some tap water is perfect and you don’t need to add calcium. I have an RO that gives me pure clean water and I like to start with a blank slate so I’m not guessing. I add calcium every watering. In 20 gal containers I water about one gal per plat per day right when my lights turn on. Not more than 5% water per volume of soil and maybe once a week I hit them with 10% to make I am watering deep enough. I’ll skip a watering the day after hiring them with 10%. Rarely do I get any runoff. No need for that in living soil. I use microbes geared for veg in veg, along with some enzymes. I switch to a different blend of microbes in flower with the same enzymes. I grow in a 4x8 in 20 gals plastic pots. I top dress dry amendment’s and worm castings. At the start of flower and that’s it. I tried growing in 5 gals for 10 yrs. I always veg too long and would run into deficiencies every time. It can be done in five gal but not going to make it to the end water only in such a small container. You can go 5 gal in coco or hydro but you have to feed those plants as they rely on you for everything they get. It’s so much easier with a larger volume of soil if you have the space. Research VPD.

there are charts online for clone, veg and flower. Dial the room in to those parameters and your plants will rage.

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Also research earth boxes if you want a smaller volume of soil and a plug-and-play system these things are pretty bad ass

Here was my calcium def

How many leaves have this? Did you drip some water or nutrient solution on them top feeding :love_you_gesture:

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Maybe half a dozen leaves starting. Nothing dripped from above, and I never spray the plant with anything.


I added Calmag to the watering at the label dose of 5ml per gallon. The spots seem to have progressed a bit and I’m seeing a little yellowing compared to the plant next to it. In fact, the plant next to it looks great so far. No spots and no yellowing. In fact, even though it is a week younger, it has outpaced the other and I had to gently coax one of the upper branches to the side to avoid then light.

Same soil in both plants. Same water-only method. No sign of pests still. This particular plant seems a little unhappy compared to its sister.

I have some Neptune’s Harvest Fish and Seaweed 2-3-1 I could add in. But I’m hesitant to just start throwing stuff into the Living Soil.

This being my first grow, I don’t expect everything to go perfect. I’m just hoping she holds on through the end, and I’d like to give her a hand if I can. I believe this is week 8 since sprouting. So I figure that’s still at LEAST 4 to 6 weeks to go.

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