Note: I originally made this post before the perks were released. I’ve updated some things since now that we’ve had hands-on experience
According to a post I saw elsewhere on this forum, Superbloom’s extra 30 damage activates upon landing 16 thorns within 1.5 seconds (Thanks Ayanga for doing the research and clarifying the actual number 
)
LW’s weapon fires 22 individual thorns per second, so 33 in 1.5 seconds. So to activate Superbloom, you would need to be hitting about ~49% of your thorns at the time on that specific target
One full clip of thorns takes about 4.5~ seconds to deplete. Once Superbloom starts activating, it does so rapidly as long as your shots are accurate enough, potentially less than 1.5 seconds apart. To test it, I unloaded a full 100 thorn bodyshots into a Reinhardt in the practice range and counted the bursts. It went off a total of six times (and the Rein was left with just a sliver of HP, for the record). So 6 bursts = an extra 180 HP damage in total, or 40 extra DPS or so
So while firing, without factoring in reload, LW could reach a theoretical maximum 173~ DPS with all bodyshots, 306~ with all crits vs non-Tanks, and 240~ with all crits vs Tanks
Also, I STILL don’t know for sure if Superbloom’s extra damage is affected by crits, so I just treated it as if it isn’t to be safe, and as far as I can tell it isn’t. But if it IS able to crit, then these numbers are even higher
