@Philindicus, I think you are potentially right there. The fact the two light green plants turned out to be so spindly and yes, had hollow stems, whilst being totally different phenotypes suggests that the environment in the medium was not ideal. I am not sure how to address the cal/mag issue. I have been adding the cal/mag/micronutrient additive at full strength during the majority of the plants life (as opposed to the primary nutrient and other additives which are generally added at between 25%-44%, to give it higher levels of calcium and magnesium to compensate for the ionic action of the coco, but it doesn't seem to work to great effect. I might have to introduce a regular foliar feed. Or maybe changing to a coco specific nutrient range such as CANNA or CX. EIther way, I was pretty quick to call Blackberry an inconsistent strain with poor genetics, but I must give full consideration to it simply being a sensitive strain that requires a more optimised nutrient regiment, which would explain why I've done reasonably well growing other strains, and so relatively poorly with blackberry.
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