My immediate thought is: MOAR RECHARGE. I almost always 4-slot my holds with Basilisk's. On a controller, you usually get more mileage out of recharge than damage buffs. You've only got Hasten 2-slotted, but you've got 3 slots in Hover for defense? If you want raw damage, you probably want a Fire/Kin. With Plant/Storm you want to make sure your best damage-dealing powers are up all the frickin' time. Your trick is probably getting them all clumped together with a corner-pull, dropping Roots until everything is nice and anchored, drop Seeds, then do Freezing Rain, Tornado, and Lightning Storm that they can't get away from while Creepers and your Fly Trap wail on them. Make sure your Fly Trap gets into melee range if you can. You should be able to easily perma-confuse all of them, and global accuracy pretty much falls into your lap on accident if you go for more recharge. Plant/Storm feels like one of the most controllery controllers to me - out of a group of 12-16, you'll have maybe one or two who can even try to attack you and even if they're both bosses, you'll probably be able to get them perma-held really fast with Strangler.
Vines is pretty crap without lots of recharge, I just can't see it really doing much - if you really want to hold things AoE, I'd suggest stacking Roots + Fissure from the Stone Mastery Epic. But you don't really need a hold when you can Confuse things. Holds will make you do less damage.
Also, you three-slotted Hover. If you're really that crazy for defense, I'd suggest dropping Spirit Tree, Thunderclap, and Vines and going with Boxing/Tough/Weave. It will free up some slots, too, because I can never see the point in taking more than 3 slots total in Tough/Weave (I normally three-slot Steadfast in Tough and three-slot LotG in Weave, leave Boxing empty unless I've got lots of slots free to six-slot it for recharge - or unless I'm playing a Brute, in which I six-slot for recharge anyway but actually use it for building fury).
In Health, what I'd suggest rather than three-slotting Miracle is grabbing the Miracle unique, the Numina's Unique, and picking which one you want two-slot bonuses from to grab the Heal. That's just my personal way to do a three-slotted regen power like Health on something that might be end-hungry - but with Consume you might not need it, especially if you go for some more recharge.
Speaking of: LotG 7.5s in Maneuvers and Weave. Hell yeah.
Roots: Slot more damage
O2: Numina unique is a proc. Its wasted here unless you use O2 every 2 minutes. Slot the unique in Health.
Carrion Creepers: Positron's Blast and other Targeted AoE sets do not buff damage from the vines attacks, only the immobilize. You need to slot common IOs in this power.
Thunder Clap: Needs more acc. This power really needs 6 slots to be effective. Since you have no other stuns to stack with it, I would be inclined to skip it.
Seeds of Confusion: At level 35? With only 1 slot? Take this at level 8 and 6 slot ASAP for acc, confuse and recharge.
Tornado: You don't have it. Tornado+Roots=LOTS of damage.
Entangle: You don't have this either. One of your few sources of ST damage short of epics.
Maneuvers: Why?
As others have said "Moar Recharge!" 
Since you're looking to do damage, slot Roots for damage or with Positron's Blast. It does significant damage, benefits from its own containment, prevents kb from Lightning Storm and Tornado, and can be spammed all day long.
Seeds of Confusion should also be taken and slotted asap, since it is an insane amount of mitigation. Once the bad guys are shooting at each other, drop Freezing Rain, Creepers, Lightning Storm, and/or Tornado while spamming Roots and your Epic AOE.
In my build (see post here), I slotted for extreme recharge and for damage. I routinely solo missions spawned for six, largely due to the safety created by Seeds of Confusion. (When Seeds misses too many bad guys, the battle can go south quickly. But the contagious confusion proc helps spread the confusion, and the chaos created by Freezing Rain, LS, Tornado, and/or Hurricane can often get your bacon out of the fire.)
Hazel Black - Mind/Psi D
Stephanie Winters - Nightwidow
Jacqui Frost - Cold/Ice D
Jacqui Embers - Fire/Kin C
Simone Templar - Fire/MM B
Mallory Woods - Kin/Rad D
Sanguine Melody - Grav/Sonic C
Fumina Hara - Plant/Storm C
Nutmeg - Warshade
Lauren Wu - SS/WP B
The freak chance of Confuse missing a bunch of people is why I'm taking Fissure: Roots + Fissure = Ohshit button.
don't forget regarding global bonuses...you have 1.88% max hp 9 times....anything after 5 won't count..you also have 2.5% recov 8 times..
i see alot of powers you went for the 1.88% max hp..i do this also..but keep track of how many times you do it
also, when going for max hp...I don't see the point in going out of yer way to get a measly 1.13% max hp..sure it all add's up, but in hover you used 2 slots for this reason only..not worth it imo..
you put 2 Energy Manip's in Thunder Storm...imo 2 thunderstrikes or some HO's would be of more use
perma jump is ---> /up 1
You can also get max hp by taking the earth epic. 
With enough global recharge, EE can be up all the time.
Hazel Black - Mind/Psi D
Stephanie Winters - Nightwidow
Jacqui Frost - Cold/Ice D
Jacqui Embers - Fire/Kin C
Simone Templar - Fire/MM B
Mallory Woods - Kin/Rad D
Sanguine Melody - Grav/Sonic C
Fumina Hara - Plant/Storm C
Nutmeg - Warshade
Lauren Wu - SS/WP B
OK a few thing just from glancing - some of these are already covered.
1: Roots gets 5 Positrons Blast including the proc, and the Trap of the Hunter Proc. If you are short on money you can go 4 Trap of the Hunter ( including proc, and 2 Positrons ( Acc/Dam + proc ).
2: O2 boost gets 1 heal till your late 30s. You will hardly ever need it.
3: Seeds of Confusion 6 slotted = win. Take it at 8. Six slot it asap.
4: Creepers gets 4 Positrons blast ( no Proc ) and 2 Recharge. Creepers is going be what kills the bad guys from 27 to 35, so until you can get enough recharge in it to have it up all the time, you will be doing a lot less damage than you could.
5: Freezing Rain is going to be better frankenslotted with 2 undermined defences, 3 Lady Grey ( including Proc ) and the knockdown set damage proc. You want this power up as often as possible, but the end will KILL, so you frankenslot with an eye towards maxing recharge, with some good end reduction and a little bit of defense debuff.
6: Stamina gets 3 regular end mods. My Plant/Storm ( my current alt at lvl 29 ) is having severe endurance issues. Mostly because I can't find the slots for end reduction yet. If you find your end working well, then slot with the set - till you find it working well, you will want everything you can get out of Stamina.
7: You will never have the endurance to run Assault. Same for Maneuvers. The good news is if you play it right you shouldn't need them.
8: Without Snowstorm and Hurricane you will run across sets of mobs( mostly Nemesis, but there are others ) that you will not be able to deal effectively with. Vines will work for them when it's up, but it's recharge is way too slow to be more than a backup for when things drop in the pot. Taking out Assault will get you one of those powers - finding room for the other is causing me some serious distress right about now 
Other things - Gale gets one slot ever. Initially it's an accuracy, later it can be the chance for recharge proc. Health gets a second and or third slot much later in the build. Even if you have both Veteran Attacks, you will want either Entangle, or perhaps Air Superiority slotted for damage to help you kill Lieutenants and bosses, or getting rid of the last couple mobs will take FOREVER, slowing you down to a crawl.
I hope I don't come off too harsh, but you are missing out on some of the powers and synergies that make Plant/Storm a true butcher and going for a much slower/more tedious build that will probably just frustrate you. I'm really enjoying my Plant/Storm - I wish you good luck with yours as well
I modified a few things on your build, I only had a few minutes (at work) to look at it..
Hero Plan by Mids' Hero Designer 1.401
http://www.cohplanner.com/
[u]Click this DataLink to open the build![u]
hardeen not dun: Level 50 Magic Controller
Primary Power Set: Plant Control
Secondary Power Set: Storm Summoning
Power Pool: Fitness
Power Pool: Flight
Power Pool: Speed
Power Pool: Leadership
Ancillary Pool: Fire Mastery
perma jump is ---> /up 1
Any Plant build that does not take Seeds of Confusion at level 8 and have it six-slotted automatically fails. Basic slotting is 2 Acc, 2 Confuse, 2 Recharge. Basic strategy for any Plant controller is get in position to maximize the cone, hit group with Seeds, lock them down and do damage with Roots. Lock down bosses with Strangler or whatever else you have. Keep using Roots for damage, refresh Seeds when necessary, until foes are dead. Once you get Carrion Creepers, you can lead with them.
Seeds need Acc-Conf-Rech. Roots needs Acc-Dam and some EndRdx. Creepers needs Rech, and some damage is nice.
From your storm side, Snow Storm is a huge help, especially while waiting for Seeds to recharge. Foes who are immobilized and have their recharge slowed are almost held -- they can't move and can only attack you once in a while. Also, Snow Storm knocks down Fliers -- since Roots won't work on anything more than a few inches off the ground, Snow Storm is particularly usefull for a Plant/Storm. I would take Snow Storm over Leadership, Thunderclap, Spirit Tree or O2 Boost.
Need more damage? Drop Hover and take Air Superiority for a melee attack. If you need to "hover," you can slot up Fly with Flyspeed and EndRdx. The knockdown in Air Sup is a great way to keep a foe occupied while you wait for your single-target hold to recharge. Another option is Super Speed. The stealth in Super Speed combines with the stealth in Steamy Mist go give you full invisibility. That's what I do with most of my */Storm controllers until I can get a Stealth IO. With a Plant/Storm controller, Super Speed is nice because it lets you get in good position for maximum use of Seeds and your various positioning tools.
Only slot a full set of Lady Gray into Freezing Rain if you have enough global Recharge. This power needs to be up as soon as possible, so replace something with a Recharge to maximize the Recharge. But if you can get enough global Recharge, then you can keep the 6th one.
If you are going to slot for Defense, then you should take one of the APP sets that give you a defense based shield, like Earth or Ice. I prefer to slot more for control and recharge, though.
LOCAL MAN! The most famous hero of all. There are more newspaper stories about me than anyone else. "Local Man wins Medal of Honor." "Local Man opens Animal Shelter." "Local Man Charged with..." (Um, forget about that one.)
Guide Links: Earth/Rad Guide, Illusion/Rad Guide, Electric Control
[ QUOTE ]
Other things - Gale gets one slot ever. Initially it's an accuracy, later it can be the chance for recharge proc. Health gets a second and or third slot much later in the build. Even if you have both Veteran Attacks, you will want either Entangle, or perhaps Air Superiority slotted for damage to help you kill Lieutenants and bosses, or getting rid of the last couple mobs will take FOREVER, slowing you down to a crawl.
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For me, Gale only got one slot until post-50 respecing into set bonuses. The 4- and 6-slot bonuses from Kinetic Crash was too good for me to pass on: Mag 3 KB protection and 7.5% global recharge.
Hazel Black - Mind/Psi D
Stephanie Winters - Nightwidow
Jacqui Frost - Cold/Ice D
Jacqui Embers - Fire/Kin C
Simone Templar - Fire/MM B
Mallory Woods - Kin/Rad D
Sanguine Melody - Grav/Sonic C
Fumina Hara - Plant/Storm C
Nutmeg - Warshade
Lauren Wu - SS/WP B
[ QUOTE ]
4: Creepers gets 4 Positrons blast ( no Proc ) and 2 Recharge. Creepers is going be what kills the bad guys from 27 to 35, so until you can get enough recharge in it to have it up all the time, you will be doing a lot less damage than you could.
[/ QUOTE ]
As I indicated above, Positron's Blast (and other Targeted AoE sets) does not work properly with Creepers. Creepers spawns a number of subpets and IO sets only enhance the relevant subpet:
1. Bramble: AoE slow. No damage.
2. Creeper Patch: AoE immobilize. 0.60 damage scale.
3. Vines: ST smash (0.56 damage scale) and ST thorns (0.46 damage scale) attacks.
Targeted AoE sets: Affects only Creeper Patch
Immobilize sets: Affects only Creeper Patch
Slow sets: Affect Bramble and Vines
Knockback sets: Affects Vines
If you want to enhance all aspects of the power, it is best to slot common IOs, SOs or HOs.
Hmmm I was relying on the Positron set bonuses to help the over all build, but you may be right. So 1 Acc, 2 damage, and 3 recharge in that case?
i tried to make a plant controller that could do damage without having to choose fire as my primary. I already have a few fire builds and wanted to try and see how good dps i could do with just plant/storm by utilizing assault, global damage,6 slotted roots and tried to stack up the hps so i didnt end up a dead duck in the water.
Hero Plan by Mids' Hero Designer 1.401
http://www.cohplanner.com/
[u]Click this DataLink to open the build![u]
hardeen: Level 50 Magic Controller
Primary Power Set: Plant Control
Secondary Power Set: Storm Summoning
Power Pool: Fitness
Power Pool: Flight
Power Pool: Speed
Power Pool: Leadership
Ancillary Pool: Fire Mastery
Hero Profile:
Level 1: Strangler <ul type="square">[*] (A) Ghost Widow's Embrace - Accuracy/Recharge[*] (3) Ghost Widow's Embrace - Endurance/Hold[*] (3) Ghost Widow's Embrace - Accuracy/Hold/Recharge[*] (23) Lockdown - Recharge/Hold[*] (48) Lockdown - Endurance/Recharge/Hold[/list]Level 1: Gale <ul type="square">[*] (A) Positron's Blast - Accuracy/Damage[*] (36) Positron's Blast - Accuracy/Damage/Endurance[/list]Level 2: Roots <ul type="square">[*] (A) Trap of the Hunter - Accuracy/Recharge[*] (5) Trap of the Hunter - Accuracy/Immobilize/Recharge[*] (5) Trap of the Hunter - Accuracy/Endurance[*] (15) Trap of the Hunter - Chance of Damage(Lethal)[*] (15) Positron's Blast - Damage/Endurance[*] (36) Positron's Blast - Accuracy/Damage/Endurance[/list]Level 4: O2 Boost <ul type="square">[*] (A) Miracle - Heal/Endurance[*] (7) Miracle - Heal/Recharge[*] (7) Miracle - Endurance/Recharge[*] (43) Numina's Convalescence - +Regeneration/+Recovery[*] (46) Numina's Convalescence - Heal/Endurance[/list]Level 6: Swift <ul type="square">[*] (A) Run Speed IO[/list]Level 8: Hover <ul type="square">[*] (A) Luck of the Gambler - Defense/Endurance[*] (9) Luck of the Gambler - Defense[*] (9) Luck of the Gambler - Defense/Endurance/Recharge[/list]Level 10: Steamy Mist <ul type="square">[*] (A) Titanium Coating - Resistance/Endurance[*] (11) Titanium Coating - Resistance/Endurance/Recharge[*] (11) Titanium Coating - Resistance[*] (13) Steadfast Protection - Knockback Protection[/list]Level 12: Hasten <ul type="square">[*] (A) Recharge Reduction IO[*] (13) Recharge Reduction IO[/list]Level 14: Fly <ul type="square">[*] (A) Flight Speed IO[/list]Level 16: Freezing Rain <ul type="square">[*] (A) Touch of Lady Grey - Defense Debuff/Recharge/Endurance[*] (17) Touch of Lady Grey - Recharge/Endurance[*] (17) Touch of Lady Grey - Defense Debuff/Recharge[*] (23) Touch of Lady Grey - Defense Debuff/Endurance[*] (31) Touch of Lady Grey - Defense Debuff[*] (34) Touch of Lady Grey - Chance for Negative Damage[/list]Level 18: Health <ul type="square">[*] (A) Miracle - Heal/Endurance[*] (19) Miracle - Heal[*] (19) Miracle - +Recovery[/list]Level 20: Stamina <ul type="square">[*] (A) Performance Shifter - EndMod[*] (21) Performance Shifter - EndMod/Recharge[*] (21) Performance Shifter - EndMod/Accuracy[/list]Level 22: Assault <ul type="square">[*] (A) Endurance Reduction IO[/list]Level 24: Vines <ul type="square">[*] (A) Ghost Widow's Embrace - Accuracy/Recharge[*] (25) Ghost Widow's Embrace - Accuracy/Endurance[*] (25) Ghost Widow's Embrace - Accuracy/Hold/Recharge[*] (37) Ghost Widow's Embrace - Endurance/Hold[*] (40) Lockdown - Recharge/Hold[*] (46) Lockdown - Endurance/Recharge/Hold[/list]Level 26: Carrion Creepers <ul type="square">[*] (A) Positron's Blast - Accuracy/Damage[*] (27) Positron's Blast - Accuracy/Damage/Endurance[*] (27) Positron's Blast - Damage/Recharge[*] (36) Positron's Blast - Damage/Endurance[*] (37) Positron's Blast - Damage/Range[*] (37) Positron's Blast - Chance of Damage(Energy)[/list]Level 28: Thunder Clap <ul type="square">[*] (A) Stupefy - Accuracy/Recharge[*] (29) Stupefy - Accuracy/Stun/Recharge[*] (29) Stupefy - Endurance/Stun[/list]Level 30: Spirit Tree <ul type="square">[*] (A) Miracle - Heal[*] (31) Miracle - Heal/Endurance[*] (31) Miracle - Heal/Endurance/Recharge[/list]Level 32: Fly Trap <ul type="square">[*] (A) Expedient Reinforcement - Accuracy/Recharge[*] (33) Expedient Reinforcement - Accuracy/Damage[*] (33) Expedient Reinforcement - Endurance/Damage/Recharge[*] (33) Expedient Reinforcement - Damage/Endurance[*] (34) Expedient Reinforcement - Accuracy/Damage/Recharge[*] (34) Expedient Reinforcement - Resist Bonus Aura for Pets[/list]Level 35: Seeds of Confusion <ul type="square">[*] (A) Endurance Reduction IO[/list]Level 38: Lightning Storm <ul type="square">[*] (A) Devastation - Accuracy/Damage[*] (39) Devastation - Accuracy/Damage/Recharge[*] (39) Devastation - Damage/Endurance[*] (39) Devastation - Chance of Hold[*] (40) Energy Manipulator - EndMod/Recharge[*] (40) Energy Manipulator - Chance to Stun[/list]Level 41: Fire Ball <ul type="square">[*] (A) Ragnarok - Accuracy/Recharge[*] (42) Ragnarok - Accuracy/Damage/Recharge[*] (42) Ragnarok - Damage/Endurance[*] (42) Ragnarok - Damage[*] (43) Ragnarok - Damage/Recharge[*] (43) Ragnarok - Chance for Knockdown[/list]Level 44: Fire Shield <ul type="square">[*] (A) Titanium Coating - Resistance/Endurance[*] (45) Titanium Coating - Resistance/Endurance/Recharge[*] (45) Titanium Coating - Resistance[*] (45) Impervious Skin - Resistance/Endurance[*] (46) Impervious Skin - Status Resistance[/list]Level 47: Consume <ul type="square">[*] (A) Performance Shifter - EndMod/Accuracy/Recharge[*] (48) Performance Shifter - EndMod/Recharge[*] (48) Performance Shifter - EndMod/Accuracy[/list]Level 49: Maneuvers <ul type="square">[*] (A) Red Fortune - Defense/Endurance[*] (50) Red Fortune - Defense/Recharge[*] (50) Red Fortune - Endurance[*] (50) Red Fortune - Defense[/list]------------
Level 1: Brawl <ul type="square">[*] (A) Empty[/list]Level 1: Sprint <ul type="square">[*] (A) Empty[/list]Level 2: Rest <ul type="square">[*] (A) Empty[/list]Level 1: Containment
------------
[u]Set Bonus Totals:[u]<ul type="square">[*]16% DamageBuff(Smashing)[*]16% DamageBuff(Lethal)[*]16% DamageBuff(Fire)[*]16% DamageBuff(Cold)[*]16% DamageBuff(Energy)[*]16% DamageBuff(Negative)[*]16% DamageBuff(Toxic)[*]16% DamageBuff(Psionic)[*]1.56% Defense(Energy)[*]1.56% Defense(Negative)[*]3.13% Defense(Ranged)[*]2.25% Max End[*]22.5% Enhancement(RechargeTime)[*]5% Enhancement(Immobilize)[*]44% Enhancement(Accuracy)[*]10% FlySpeed[*]175.5 HP (17.3%) HitPoints[*]10% JumpHeight[*]10% JumpSpeed[*]Knockback (Mag -4)[*]Knockup (Mag -4)[*]MezResist(Confused) 10%[*]MezResist(Held) 10%[*]MezResist(Immobilize) 12.2%[*]MezResist(Sleep) 16.6%[*]MezResist(Stun) 10%[*]MezResist(Terrorized) 10%[*]18% (0.3 End/sec) Recovery[*]52% (2.21 HP/sec) Regeneration[*]10% Resistance(Smashing)[*]10% Resistance(Lethal)[*]15.4% Resistance(Fire)[*]15.4% Resistance(Cold)[*]10% Resistance(Energy)[*]10% Resistance(Negative)[*]18.1% Resistance(Toxic)[*]10% Resistance(Psionic)[*]20% RunSpeed[/list]
Go easy on me, ive never played a plant controller before and didnt quite know how to slot him so this is merely a rough draft.
Any tips greatly appreciated