"Australian pine" (Casuarina equisetifolia) grown from seed. Thoughts?

[Matt B]

I live in Florida and I thought I'd have a go at A local invasive species. I grew up near the coast and while I always remember seeing mature specimens growing seemingly directly out of the salt water bay. A directed months-long hunt produced zero immature specimens that I could collect and thus do the parks caretakers a favor. So last summer I went and collected a few seed pods, shook the seeds out of them and planted 20 of them, and ended up with three viable seedlings. They seemed to be growing straight, with little branching or interesting features, so early this summer I introduced a few mild curves and they have been growing well. I want to up-pot these, but I know some species are very picky about root work in the fall. The temps here are 80-90 degrees daily and getting down to upper 70s at night. Should I wait til early spring to repot them or can they handle work this time of year?

 

[Shibui]

Young seedlings like yours can be repotted, including root reduction any time of year.
I do most root work on more mature Casuarina in late spring or summer but that's in a cooler climate. Growers in warmer parts of the country tell me they root prune any time of year. I'd assume your temps would allow root work on Casuarina any time of year.
For growers in cooler lomates, most of our Australian native plants respond more like tropicals so recover much better when root pruned in warmer weather, even if the plants are actively growing. I have only worked with other Casuarina species but assume equisetifolia will be similar.

 

[nuttiest]

I so miss those trees - they were a staple for anyone needing set up in shade while at the beach. Ours never grew closer than 70 ft from shore. After removal, that side of the island is filled with native sandspurs and just sand instead.

 

[Matt B]

I so miss those trees - they were a staple for anyone needing set up in shade while at the beach. Ours never grew closer than 70 ft from shore. After removal, that side of the island is filled with native sandspurs and just sand instead.

Here they just leave them be. They are not exceptionally fast growers, and they don't litter the place with seedlings. They grow right into the bay, to the point that the high tide hits the trunk, and they occasionally fall down from rough surf and wind from hurricanes, leaving fantastic driftwood trunks behind. I often wonder how they can tolerate rooting in sand that is right on the water. The roots are technically under salt water, and as we know as bonsai practitioners, soaked soil and high salt content is death to trees. Instead, they thrive on it.

 

[Shibui]

Some other Casuarina (technically Allocasuarina now) species grow right down to the high water mark so they must have some way of dealing with salty water. At the beach they have the advantage of tidal fluctuations so spend half the day with aerated root zone but some also grow around the margins of swamps so can also tolerate constantly wet roots. There are quite a few species that can cope with constantly wet roots - Bald cypress, Dawn redwood, some Callistemon and Melaleuca love similar wet areas so soaked soil is not always a death sentence for all trees.