Some things like Turnips and Melon patches generate in the world - which should be easy to fix.
The Double Height plants will need looking in to as they may have changed a little.
Mushrooms have a separate issue.
Smaller plants like the Fire Bloom etc. will need doing.
Moss and Mould will probably be a pita to do with all the blockstates :(

Turnips and cabbages done. :)

Just moss and mould to go \o/

Algae is the last thing on the list to do now