Karen, as far as I remember Superthrive is mostly vitamin B1 (which plants make themselves so don't really need) and a hormone (auxin). I don't remember for sure, or what else is in it, but I know I looked it up for someone once before so I will look it up again to remind myself and post back later. If it is 0.5-0-0 it is a weak fertilizer at best and I don't know if it would be available to Mayo in the Netherlands anyway. I've never seen it here in Canada, and if articles on the web are accurate it's not sold here.
