Yellowing, brown spots, leaf tips curling down.

These plants are in their 4th week approx. Auto fem's - Critical Mass. I've planted them in miracle grow soil and have only fed once with 2/3rds strength canna vega terra. I posted some pics last week when i noticed the tips curling and have not added any more nutes and the prob is getting worse. Any ideas?



NB: The curling down started about a day after the first feed. I also have another plant of the same age that has had the exact same treatment but the problem is less severe, with only a couple of the very low leaves showing similar symptoms.

In my earlier post i was told that it may be a mg prob or the fact i put veg nutes into 'hot' soil and have over indulged them in N. However, everythin i've researched about N overdose does not match these leaves. I think it's either N def, Mg def or... trouble is alot of these def's look the same. I hope someone has seen this before and knows what to do, thanks.

it appears to be Mg def. Miracle Grow Patio, i think it is, has trace minerals, but the others do not. something like that. i'm a control freak; i control my own fertilization.

Magnesium Def is your best bet (about 60% likely) lower leaves turning yellow and pale while veins remain dark green. The only thing is that the tips and edges of the blades should be curling upwards... Are they? if yes add fertilizer with Mg.
Nitrogen Def (30% likely). Do you have red stems and/or stunted growth? Is the yellowing of the leaf quite fast? if yes.. add fertilizer rich in N.

Overfertilizing (10% likely) Symptoms look a lot like it, especially the burnt tips and necrotic spots but since you've only fed it once and not a full dosage I seriously doubt it. Flushing 3gals of water for every gal of soil and then letting it recover for a week would help.
Best of luck mate. Hope this helps
Keep it green!! (not yellow) lol

Ok thanks, i just assumed miracle grow would have everything a plant needs but my mistake i guess. So should i water with some epsom salts? or try foliar feeding? And will i need to continue to add Mg on a reg basis?

most cannabis ferts have it. the trick is.........you're in hot soil already. use epsom salts. a solution to the root zone will suffice. i don't like to spray salts on my plants.

MrNash said:

Magnesium Def is your best bet (about 60% likely) lower leaves turning yellow and pale while veins remain dark green. The only thing is that the tips and edges of the blades should be curling upwards... Are they? if yes add fertilizer with Mg.
Nitrogen Def (30% likely). Do you have red stems and/or stunted growth? Is the yellowing of the leaf quite fast? if yes.. add fertilizer rich in N.

Overfertilizing (10% likely) Symptoms look a lot like it, especially the burnt tips and necrotic spots but since you've only fed it once and not a full dosage I seriously doubt it. Flushing 3gals of water for every gal of soil and then letting it recover for a week would help.
Best of luck mate. Hope this helps
Keep it green!! (not yellow) lol

Click to expand...

Thanks mate erm some are curling up and some down. I did also notice today that some of the leaf stems have red colouring on the upper side. Looks a bit like rhubarb. With regards to stunted growth they've slowed down considerably in the last week or so, but i thought this was normal as they've started to flower but they are doing this really slowly. So does this provide more evidence for N def?

stonecoldsober said:

Ok thanks, i just assumed miracle grow would have everything a plant needs but my mistake i guess. So should i water with some epsom salts? or try foliar feeding? And will i need to continue to add Mg on a reg basis?

Click to expand...

For plants epsom salts can supply two essential chemicals that they need, ie Magnesium and Sulphur in a soluble form absorbable through both the leaves and roots. At the dilution plants need it, it is also friendly to the soil/compost micro flora and stimulates the micro herd.

Overdone like anything it will cause harm to the soil and its fauna. Like everything its about balance. If the plant does not need it don't give it.
Dosage for misting:

1 level teaspoon to a heaped teaspoon per litre of water.

Dosage for watering:

1 level desert to a heaped tablespoon per 5 litres of water.

Dissolve the epsom salts in some hot water first to make sure it has all dissolved properly.

Applications:

1. As a foliar misting after lights out. Repeat this every three days until you see an improvement.

2. Use when watering/feeding in compost: Once in the vegetative stage, & twice when in flower (day 10 & day 35).

Hey, just to update, I've fed them with 1 ltr water each per 1tsp epsom salts. The plants responded by looking greener. I though i was out of the woods but the problem looks like its getting worse.




Plant 1


Some red stems, brown spots, lost a few lower leaves.



Plant 2



Some red stems, brown margins, lost some lower leaves but overall this is the biggest and healthiest of the two.



Plant 3



This is just some bagseed that i've had vegging alongside, have now taken a clone. Looks healthy, i've also given a small feed of empsom salts


So.. Any ideas folks?

I keep having problems in soil think ive come to the conclusion if you see a deficiency flush out the soil then feed havent figured out how long after to but my situation may help yours.

Plant three looks awesome btw.

Cheers man, i have given them a flush and some bloom nutes. fuck knows what is going on i got leaves dropping off all over the place. Buds are looking small and showing little signs of growing. Plant 3 has had nothing but Mg and is happy as larry. When these autos have finished or died i will put plant 3 into flower with no nutes at all and see what happens