It appears that the tips of your leaves show toxication due to over feeding, or is a result of an inappropriate Ph level. We use to trim the PH at the growing stage down to 5.8 gradually increasing to 6.0 for blossoming. Not sure what sort or levels of humus you did use, but perhaps you should consider applying a root fertiliser such as Rhizothonic (Not sure whether you have it there, it is the most commonly and popular root fertiliser here in The Netherlands. Humus may look great but dependend of the sort of, it could have a great effect on PH levels. Since you are growing outdoors, I would not bother too much about feeding, provided the soil has a natural and normal composition. Feeding only is necessary when EC levels drop as low as below 1.0, we use to feed up to EC levels of 2.0 at the start of flowering, up to 2.4 for the last 3 weeks (which is without CO2 enrichment by the way).

Good Luck!