Marijuana deficiencies

A question from a fellow grower:

I have your WW auto here. About two weeks sprouted out of soil. I think I started too shallow and they came out a little early. Don’t know if that hurts them. Also started too low RH with no fan but venting the closet with open door. The soil was probably too dry at first. Now room is 23 Celsius to less than 28 celsius. RH about 50%. Constant oscillating fan.

Black Gold Organic soil w worm castings
Black Gold Organic starter soil
12 liter buckets
2x 300w Apollo led (100x 3w) (still playing with distance) I read too much and went with 18/6 for about a week or 10 days then went 24/0 for about 4 days. I read that might have stressed them. Just switched back to 20/4 last night.

All I have given them is Soil Mender liquid fish 2-4-1. I gave it at a low dose and low watering. About a week later with no improvement I tested soil ph, N, P, K. Found low N and P. So I gave them liquid fish again after a real watering. Ph is between 6.5 and 7. I hoped that would drop with liquid fish, not sure.

Well it’s been a few more days. New growth is dark green but drooping. This deficiency or problem is from bottom up. It has moved to the second set of leaves. Only a couple plants like this. All have twisted, dark green leaves. Or at least the ones that aren’t rusty spotted looking. They seem to start very dark green and then rust spot look starts.

Any ideas?

1st. I have a hard time helping growers that use a 24/0 photo period. You cannot have proper photo-systhesis under that photo period. Shifting your photo period around is not a good idea. I never use more than 16/8 myself, but I am not going to go into that here.

Black Gold is “Hot” Cow manure is the catalyst in this mix I believe. Did you add 1/'/3 perlite for oxygenation of soil? Also; You do not need to give nutrients to young vegging plants in Black Gold. The nutrients are already there, and should pretty much last through the veg cycle.

2-4-1 fertilizer is inadequate for plants needing nutrients in the veg stage. There should be a higher N value, and higher K value balancing out the nutrients. You should run a balanced formula if at all, when using Black Gold.

I am visually impaired, and cannot tell whether or not you have a lot of trichomes on the leaves or spots. If spots; It might be Spider mites. They love Cow manure soil mixes.

Hope this helps. :slight_smile:

BTW. What was the N-P-K value of the Black Gold :?:

It really looks like a nutrient lockout or deficiency, brown or orange flecks/spots in the leaves, most likely a potassium deficiency, maybe a manganese deficiency. It does look like it could be a pH issue, are you sure your pH is 6.5? Or is it possibly 7 or higher? Also are you watering it with hard alkali tap water? What is the pH of the water you are giving it? The 2-4-1 you are feeding them could be part of the problem as it has such low potassium.

As far as the photo-period is concerned, I always say 24 hours of light per day to get the most out of an autoflower. And only start introducing a dark period if the grow is going significantly longer than it should.

I personally have never had any problems with 24 hours of light during veg regardless of the strain.

No matter the type of photoperiod strain, autoflowers or “short day flowering” “normal photo-period” strains, consistency is very important, you can’t be giving it more, and then less and then more again. Shortening the photoperiod regardless of the type of cannabis strain will mess some with the hormones that would normally tell the plant it is getting closer to winter and needs to hurry up and finish the circle of life, a.k.a. hurry up and flower and make seeds if possible.