hardy water plant propagation speed

by John
(Birmingham UK)

How long does it take for them to show through the pea gravel?

Doug says you should be able to see the crown of the plant sitting on top of the pea gravel. How fast it starts throwing new shoots depends on water temperatures. Cold weather and water will slow things down so there is no hard and fast rule in the garden. In nursery propagation, 70F water will produce a new shoot in 6-8 weeks.