Dark Patches on Seedling leaves

mushka · May 9, 2026

Hi Hope every one is fine..
im a first time grower indoors.

il try to give as much info as possible
im the Uk
im growing in soil i germanated 2 seeds in Canna terra seedling mix.
which are 11 & 12 days old, 1 is skywalker cookie & other is Og kush feminized plants. in last 18 hrs 1 of the Seedlings has some like dark patches on leaves. ive googled it & not sure.

Thought i would ask you Fine Growers on here if you have any idea's of what it could be..
My light is Mars Hydro ts 1000 at 20 inches & is at 15%. Temps are 22 - 26 C
Humidity is between 58 - 67. im in a Hard water area ph is 7.8 ive been mixing Rain water 50/50 ratio ph goes to 7.2 ive added ph down & final ph is 6.3 - 6.6..
ive not added any type of nutrients or calmag. only thing ive added is Worm Castings. im watering every 3 - 4 days

BearWater · May 9, 2026

Whats the medium? Is the pot dry when you go to water or are you just watering on that schedule regardless?

Gmix · May 9, 2026

That doesn’t look good at all
I’d reply to @BearWater hes a fine fella & will help you out

Reply to him using the reply bottom so you tag his name & get his attention as it’s easy to miss a reply

Ninjadogma · May 9, 2026

mushka said:
Hi Hope every one is fine..
im a first time grower indoors.

il try to give as much info as possible
im the Uk
im growing in soil i germanated 2 seeds in Canna terra seedling mix.
which are 11 & 12 days old, 1 is skywalker cookie & other is Og kush feminized plants. in last 18 hrs 1 of the Seedlings has some like dark patches on leaves. ive googled it & not sure.

Thought i would ask you Fine Growers on here if you have any idea's of what it could be..
My light is Mars Hydro ts 1000 at 20 inches & is at 15%. Temps are 22 - 26 C
Humidity is between 58 - 67. im in a Hard water area ph is 7.8 ive been mixing Rain water 50/50 ratio ph goes to 7.2 ive added ph down & final ph is 6.3 - 6.6..
ive not added any type of nutrients or calmag. only thing ive added is Worm Castings. im watering every 3 - 4 days
View attachment 2638056

I've seen that behavior before and it happened when I was reusing dirt... So I'm going to say what that likely is, is "salt lesions."

You need super mild nutrients in the dirt. Earthworm castings are a super mild nutrients going in but becomes "hot" when microbes begin to go to work. EWC are a great N source but it comes online too quickly for a seedling. If you want to amend something for some N availability that'll be there later when it needs it and not fry your seedling, take a look at feather meal or crab meal.

One more thing and I might not be accurate but it seems to me that if you get salt lesions from ewc it's a different color than other spotting and tip burns. It tends to look pale grey or grey brown vs browning or yellowing.

mushka · May 9, 2026

BearWater said:
Whats the medium? Is the pot dry when you go to water or are you just watering on that schedule regardless?

Hi thanks for the quick reply. the Medium is Canna Tera seed mix. im doing the nuckle - finger test top few cm are dry before i water

Ninjadogma · May 9, 2026

mushka said:
Hi thanks for the quick reply. the Medium is Canna Tera seed mix. im doing the nuckle - finger test top few cm are dry before i water

The canna terra is fine, it's adding the ewc up front that caused an issue. And it's not a bad move, just the timing is. Based on its current size, now would be a time you'd want to mix a little bit in, not earlier.. and the ewc would come online in about 7-10 days when the seedling is finally able to take nutrients in through the roots. Early on, they're using nutrients they brought with them in the seed and any EC in the dirt is just noise to them.

mushka · May 9, 2026

Ninjadogma said:
The canna terra is fine, it's adding the ewc up front that caused an issue. And it's not a bad move, just the timing is. Based on its current size, now would be a time you'd want to mix a little bit in, not earlier.. and the ewc would come online in about 7-10 days when the seedling is finally able to take nutrients in through the roots. Early on, they're using nutrients they brought with them in the seed and any EC in the dirt is just noise to them.

cheers do you think the seedling will recover from this or any recomendations on what i should do.

greengrower73 · May 9, 2026

mushka said:
Hi Hope every one is fine..
im a first time grower indoors.

il try to give as much info as possible
im the Uk
im growing in soil i germanated 2 seeds in Canna terra seedling mix.
which are 11 & 12 days old, 1 is skywalker cookie & other is Og kush feminized plants. in last 18 hrs 1 of the Seedlings has some like dark patches on leaves. ive googled it & not sure.

Thought i would ask you Fine Growers on here if you have any idea's of what it could be..
My light is Mars Hydro ts 1000 at 20 inches & is at 15%. Temps are 22 - 26 C
Humidity is between 58 - 67. im in a Hard water area ph is 7.8 ive been mixing Rain water 50/50 ratio ph goes to 7.2 ive added ph down & final ph is 6.3 - 6.6..
ive not added any type of nutrients or calmag. only thing ive added is Worm Castings. im watering every 3 - 4 days
View attachment 2638056

How is the air movement around your plant? has it been sitting under a dome with no air? they need fresh O2 without it you can get mold, quickly. ,

mushka · May 9, 2026

i took dome off shortly after seed germinated.. i have oscilating fan but its pointing away from plants & ive a carbon filter fan that extracts air out of tent.

will the seedling recover from this

Gmix · May 9, 2026

From what I read seems to be the problem yes it should recover & having the fan not pointing on them directly is a good move.

I know what bear was getting at with the watering or at least think so.

Roots need to breathe & to much water & they can’t giving root rot a chance to get hold. Water as needed & make sure you’re not overwatering.

Must admit it looked like mold or something fungal however @Ninjadogma knows his stuff
Lotta good growers on here tbh

BearWater · May 9, 2026

mushka said:
Hi thanks for the quick reply. the Medium is Canna Tera seed mix. im doing the nuckle - finger test top few cm are dry before i water

Ninja knows whats up! : )

As far as the finger test, i like to give a nice dry back and how i do that is weigh the pot(heft it if you can). Dirt might still be moist below the finger. you’ll feel how light it is. Over watering can happen quickly with seedlings.

Galgrows · May 9, 2026

And try watering around the outside of the seedlings not on top. Let those roots search for the water they don't need very much at this stage.

GNick55 · May 9, 2026

i’d start over

Ninjadogma · May 9, 2026

mushka said:
cheers do you think the seedling will recover from this or any recomendations on what i should do.

I'm going to say just leave it be and give it the best quality of care you can and allow it to push through. EWC salt isn't likely going to fry the whole plant and once it has an opportunity to lay some roots and eat, it should be fine.

Ninjadogma · May 9, 2026

BearWater said:
Ninja knows whats up! : )

As far as the finger test, i like to give a nice dry back and how i do that is weigh the pot(heft it if you can). Dirt might still be moist below the finger. you’ll feel how light it is. Over watering can happen quickly with seedlings.

I'm still as confused as the next guy... I'm just starting to recognize certain patterns to my own screw ups

BearWater · May 9, 2026

Ninjadogma said:
I'm still as confused as the next guy... I'm just starting to recognize certain patterns to my own screw ups

hahaha! but that was a great call on your part! : )

And if we aren’t learning something id say it’s time to hang it up!

mushka · May 10, 2026

Thanks for the advice & info..
it Means alot as ive never grown weed before.. ive searched online etc & got loads of Mixed info..
i thought i would join this site & ask.
you Awesome Guys & Girls as you will know alot more of these kind of issue's & problems.. ive got 2 seedlings that are in same tent & only 1 has this issue i water both at same time & give same amount of water. il do as bear said & i will get some scales to weigh them dry & after watering.
i will see how the seedling progresses.

Really Apreciate your help..

Dark Patches on Seedling leaves

Dark Patches on Seedling leaves

mushka

BearWater

If you were a hotdog would you eat yourself?

Gmix

Ninjadogma

mushka

Ninjadogma

mushka

greengrower73

mushka

Gmix

BearWater

If you were a hotdog would you eat yourself?

Galgrows

GNick55

Ninjadogma

Ninjadogma

BearWater

If you were a hotdog would you eat yourself?

mushka

Dark Patches on Seedling leaves

Dark Patches on Seedling leaves

mushka

BearWater

If you were a hotdog would you eat yourself?

Gmix

Ninjadogma

mushka

Ninjadogma

mushka

greengrower73

mushka

Gmix

BearWater

If you were a hotdog would you eat yourself?

Galgrows

GNick55

Ninjadogma

Ninjadogma

BearWater

If you were a hotdog would you eat yourself?

mushka

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