The four-GCD rule.

Okay, so I decided to start throwing together notes on how I heal as a tree druid, in the hopes that someone will read it and be a better healer for it. If I get enough of these together I may compile them into a guide and post them on the Druid forums. At any rate, here's the first one.

Something I've learned when healing as a Druid is that you're somewhat restricted by refreshing your lifeblooms periodically. This is just how it is for us; by no means should you not stack lifeblooms on the tanks, but it is necessary to learn how to heal around them. The 7-second duration of lifebloom means that you'll get four GCDs, plus an extra second or so of slack time, in each rotation. The slack time means that if you're quick and have minimal lag (speaking from an Australian point of view; minimal lag is ~200 ms over here) you can use Regrowth in these rotations instead of an instant cast, however you're more likely to lose your lifebloom stack.

When you're healing one tank, you should lifebloom him every fourth cast.

i.e. Lifebloom, free, free, free, Lifebloom, free, free, free

Two tanks just adds a second lifebloom in every rotation.

i.e. Lifebloom 1, Lifebloom 2, free, free, Lifebloom 1, Lifebloom 2, free, free

Replace these free GCDs with rejuvenation, regrowth, swiftmend, or lifebloom (for raid heals).

Remember than NSHT takes two GCDs (one to cast HT, one to shift back into tree form) but shifting back isn't urgent.

Don't be afraid to let your lifeblooms expire (especially now that trinketing lifeblooms doesn't work) - a bloom for ~1.4k, swiftmend for ~3.5k, NSHT for ~5k can save a tank's life in two GCDs, and bringing your lifebloom stacks up again isn't mana-intensive. However, you'll get more overall HPS and HPM from keeping them rolling than letting them bloom.

To switch from healing one tank to healing two, it's best to refresh your lifebloom on the first tank, then stack three on the second, then immediately refresh the stack on the first again. This will make the new tank the first tank in your rotation. (A situation where this is used is on the Bear boss in ZA, as he switches from bear form to troll form).

Anyway, that's all I can think of for now, so I'm off.