Thanks Jaime for the hint of freezing the leaves. Stinging nettle will be available soon so I'll stock that for later use.
Sorry to hear about the fridge bailing out on you.
You think there will be a problem using dried trimmings from my other planted tank? I have some plants that will always grow like a weed and I was thinking on drying the trimmings and use them for food but I'm reluctant to do that because of the ferts I use. Don't know how much Copper plants will store and that might end up harming the shrimp.