Red/purple leaves + rusty spots

Hi all,


My plants are in their 5th week of flowering. They are grown in dirt under T5 lighting. I am growing two varieties and one starts to look weird.
The leaves, young or old, start turning red or purple. There are also some kind of rusty spots on them.I start wondering if I do not have a kind of rust fungi...
From what I have read, all the environmental conditions for it are here: low temp at night (about 65°F) and quite high humidity (60%).
What's weird is that these symptoms do appear only on one of the varieties I am growing. Any idea?

what are you feeding them

the colour of your leaves are due to the colder temps.. not alot to worry about here.
normally rust spots will be down to ca or mg.

bobtokes said:

what are you feeding them

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I use Canna Terra Flores and some molasse

My 2 cents is its nitrogen deficient. Cool temps could be playing a role but 65 is not all cool. Just about right actually. But like you said its only happening to one plant so It could be a combination genetics, nitrogen and cool temps. If it were my plant I would feed a bit of Fish Emulsion along with its regular diet the next couple weeks.

salt buildup? what strength have you been feeding them? how often? you ever run straight water between feeds?

ratyatior said:

Hi all,


My plants are in their 5th week of flowering. They are grown in dirt under T5 lighting. I am growing two varieties and one starts to look weird.
The leaves, young or old, start turning red or purple. There are also some kind of rusty spots on them.I start wondering if I do not have a kind of rust fungi...
From what I have read, all the environmental conditions for it are here: low temp at night (about 65°F) and quite high humidity (60%).
What's weird is that these symptoms do appear only on one of the varieties I am growing. Any idea?



View attachment 2525718View attachment 2525719View attachment 2525720View attachment 2525721View attachment 2525722

Click to expand...

Other than needing a little bit more Nitrogen, what you are seeing is the chlorophyll changing colors. This can be caused by a lot of factors, but it all goes back to genetics. Currently I have one strain doing what you are showing except all red, and another strain showing all purple edges, the rest not showing anything like it. Colder temps can cause this to happen, and then sometimes it just happens regardless.

Are the rusty spots you are showing on the top or bottom portion of the plant? Picture 3 to be exact. That is the only place I see damage, not enough nitrogen/cal/mag. All the other pictures look totally normal. Remember this is a flower, and it has the capability of turning a whole bunch of different colors.

make sure your PH is at 6.5 for best nutrient absorption. give them an extra dosage of nitrogen, plus a small amount of cal/mag. Or Epson salt.

View attachment 2526717 this may help