Yellowing leaves and brown spot.

Hello, this is about my first post on rollitup.org, I have been following this forum for quite a long time and it is in my opinion the best forum about cannabis. The fact that this is my first post is a good thing, the threads and mainly the search function have answered all my questions! It is now time to step in and ask, this will probably get me into answered others people questions and thus contributing to this great forum. Pardon my English, I am a french Canadian (still I think I'm better than some english folks on internet )

Anyway, I've had great success growing cannabis in soil and now wanted to take further control of nutrients by going soilless. So I bought some B'cuzz Hydromix HP and germinated some seeds a month ago. Last week, older leaves started yellowing and some brown spot appeared on them. This week it is worse and I'm wondering why! I must admit that two weeks ago I've been out for the week and soil dried out enough for the plants to eat tips of their leaves.

Is it a nutrients defiency? Since I'm soilless I know I have to supply all nutrients by myself but I already started giving seedling doses of nutrients to the plants. They are 3 weeks old today (starting fourth week) so I kinda started giving the doses of vegetative week 1.

As follow in ml/L

AN SensiGrow A - Week 1: 0, Week 2: 0.8, Week 3: 1.2, Week 4: 1.23
AN SensiGrow B - Week 1: 0, Week 2: 0.8, Week 3: 1.2, Week 4: 1.23
AN B-52 - Week 1: 0, Week 2: 0.2, Week 3: 0.3, Week 4: 4
AN Sensizym - Week 1 to 3: 0, Week 4: 5
Blackstrap Molasses - Week 1: 0, Week 2: 0.2, Week 3: 0.2, Week 4: 0.8

This is per Advanced Nutrients calculator. I never ever put that much nutrients into so young plants when in soil but figured it would be okay because I'm soilless.

Let me know what you think, I've attached some pictures of the plants and one of a nice buds I'll be harvesting in a couple of day. Sorry picture suck, I have no digital camera and taking pictures under HPS light with an iPhone is hard. The one under CFL are already much better.

They need alot more Phosphorus for starters.

So that would be under fertilizing and some of the damage caused by under watering.

I will feed more often and see how it goes. Will definitely post pictures of how it turns out.

By comparing my plants to others here that have problems I am happy with the size of my three weeks old plants! Anyway I'm not on my first grow ever, only first grow soilless.

nitrogen deficiency

id say flush them babys for a few days see what happens

You'd think the problem is too much nutrients? Doesn't look to me like nutrients burns and considering this is soilless.

What kind of pH should I go with soilless? More like real soil or more like hydro?

I just flushed them with lots of pH balanced water (6.8 ). The runoff is very yellow and is around pH 6.0.


I think I'll experiement different things on different plants and I'll see how it goes, I guess I'll learn doing some mistake. Anyway those were leftover seeds I had, just didn't want to experiment soilless with my $$ Dutch Passion Strawberry Cough seeds haha!

So I think I just saved them, repot them in #6 pot today and cut off the yellowed leaves. Then feed them with SensiGrow only.

I saw the root system while repotting them and they look great and fully packed. I think the problems could have come from there, some root got out of the bottom of the pot and may have sit in salted nutrients. Also an error I was doing is not letting enough runoff to remove those salt and I let the runoff in the bottom of the container so salt buildup there was obvious.