Originally Posted by pureice739
Hey guys, some friend of mine has a problem with a few of his plants. They are all white widow from dutch passion, in veg about 3.5 weeks in vegging under 600 watt vero 29's. He has 20 plants in total they ALL look great besides three of them, what can it be? Here in the pix you can tell which once need some special attention, and which look good and healthy, any ideas? thanks guys
BTW here are some details, they are on COCO.PERLITE 50/50. Running BioBizz coco nutes on tap water , ph 5.5-5.8 hand watering daily.
It looks like the plant in question may be either too close to the lights, or 'praying for magnesium'.
UPDATE - All these plants are on the edge of magnesium deficiency. Even the ones who look 'great' have very dark green leaves, the veins of the leaves are almost indistinct, and the internodes are extremely short. Cannabis uses quite a bit of magnesium, on a near constant basis. Magnesium is basically connected to the foliage, and to phototropism. If plants are green and have a lot of leaves, they use more magnesium. Don't give too much because it can burn roots like nitrogen. My guess is also that your water might be soft, which is not necessarily a bad thing, however soft water needs extra calcium and magnesium. Also remember to add a little silica. It isn't in soilless mixes or hydro - outdoors it would come from sand. Resin is made from silica.
Just a general observation.
Why so much perlite? Coco coir is already very aerated and fluffy. It already has a pH of 6.0, and if you adjust your nutrients to 6.0 throughout the grow, the pH is very stable. Perlite has a higher pH of 7.0. It's not needed, and complicates things.
Then, if you give a seed, or a newly transplanted plant bloom food with more potassium, you're growing a plant with a very strong root system (P) and a strong stem (K).
And that means much faster growth, much more resilience, and much less pest pressure, much fewer and more easily treated incidents of nutrient deficiencies, because the bigger root system takes up more of the nutrients. Also excess nutrients don't sit in the soil and drag the pH down.
Build a root system and stem/branches first, and the foliage takes care of itself.