On 10/06/17 14:23, Clive George wrote:
I know the answer is "depends on the plant", but I was wondering how
long it would take for the energy investment a plant makes in growing eg
a new leaf or stalk to be recouped.

I thought here might be a good place to ask - any ideas?

What do you mean by 'recouped'. They energy the plant gathers is used to
create some seeds. Once that is done then it's 'purpose' has been
fulfilled. When it dies that energy is returned to the soil, moulds,
bacteria...