I'd take pretty much everything in the primary except spirit tree and entangle. From the secondary, everything but blazing bolt. Maybe fit in hasten and aid self as well if you can. If I was soloing I'd use spore burst/seeds or maybe creepers/seeds to open. Once they are all bunched up together nicely (seeds tends to do that) you can shred them with your fiery cones and AOE's.
My MA IDs:
Fiend Space: 211464
Hehe get back to work... gave ya a list of what to take lastnight mate, but go take a good look at the US guide list, will give nice ideas as to what to slot where 
Luckily Confusius dosn't do much solo (or is that unluckily) he gets to duo lots with Lady Zdrada a grav/psi dom, don't worry mate, it all changes at 8 when you get your seeds tonight..
Remember "if its floating 2ft off the ground, it's already held" and "not that group, This one!" hehe we are going to have alot of accidents, but don't worry, you will get it eventualy, your already doing a better job than your MM
Urm, allready hit 8 last night. MWAHAHAHA.
With plant/ you can skip the AoE hold (Vines).
It's got long recharge and short duration. And you got a much much better tool: Teh Seeds! More effective, way shorter recharge and longer duration in one pack and topped of with 1/3 activation time of that of Vines.
It's got shorter range -actually in good agro range of mobs- so you'd want some form of stealth (IO in sprint, and/or SS as travel) for easier positioning, even more due to it being a cone. Some stealth is brill anyway though.
Plant/fire rocks. Enjoy! 
Does any one have any good ideas for a build for a good all round plant/fire domm. Have just rolled one and am having loads of fun. Have a few ideas and a general 'clue' but any advice would be gratefully recieved.