My number 1 Sunflower build is currently blossom and vampire flower in fact! It lets me heal/overheal not only up to 2 allies, but an ally and myself as it arcs back if no other 2nd target is available, and of course vampire flower let's me heal myself as well. Ever since they made blossom cost 5 points I switched to this build; I used to have blossom with cocoon.
I like the idea of the Cocoon for Sunflower, because it's great at giving allies extra durability in a fight (which in turn gives you more protection because your allies have more health to fight with). Despite its cost, I would say it's very effective because that little bit of extra health can make a different (especially Oaks and low-health plants, such as Acorn and Nightcap). Pairing the upgrade with Pocket Protection would be very handy as you can, overall, gain some more health as doing so. I've only noticed a handful of sunflowers which have it (as when I've been healed, can tell if I gain extra health or not). The people who do so should keep doing so, it gives snipers and attackers extra durability in the fight. 😃
@Iron_Guard8 I haven't tried Blossom, but it seems like it's very effective, and if it can heal you as well (without other targets) it seems like a great upgrade to also increase your resistance to damage! 👍
