Some thoughts: you can start with the standard plants: Dandylion, Bulb, Spore, Lonefire. To summon BRD, there's Debris ofc, and then there's also the option of Twilight Rose Knight. Use him with level 4 Plant-type monsters, like Botanical Lion or Lord Poison, if you decide to include him. Blue Rose Dragon also seems to fit the theme, so add that too. If you run Lord Poison, or really just the Blue Rose Dragon, you can use Tytannial as a boss monster, that can be revived by both of those.
Tengu works well with Plants, so you can add that. Also, you might be using BRD's 2nd eff a fair bit, so you could run Tour Guide to make a fast Leviair and SS back the removed monsters.
For spells and traps, you can just run something similar to what Plant synchro/Tengu Plants run.