For those of you who are unfamiliar, the old lifebloom used to be:
Heals the target for [XX] over 7 sec. When Lifebloom completes its duration or is dispelled, the target instantly heals themself for XXX and the Druid regains half the cost of the spell. This effect can stack up to 3 times on the same target.
There are two essential differences. First, you could cast it on as many targets as you wanted. Second, the spell was more expensive up front - but when it bloomed you recovered mana. This made rolling lifebloom on a single target in perpetuity more mana intense, but it rewarded putting a few stacks on other targets because of the bloom.
The reason this change would be beneficial to healing druids is because it provides more interactive gameplay. If a player intelligently preempts damage with lifebloom they are rewarded with mana efficiency. This, I feel, is much more rewarding than the current "keep lifebloom rolling at all times" spell it has become.
This will, of course, change the nature of the spell from a tank healing spell into a more general healing spell. To compensate for tank healing change Nourish to additionally heal by 10% if rejuv is on the target, 10% if regrowth is on the target, 10% if lifebloom is on the target and 10% if wild growth is on the target - for a max potential of 40% additional. This is instead of the current 20% if any of those spells is on the target.
Finally because of this Omen of Clarity needs to change as well. Instead of a 4% chance to proc on each lifebloom tick, I propose a 1% chance to proc every time regrowth, rejuv or lifebloom ticks, as well as an additional 5-8% chance every time lifebloom blooms.
For pvp, if its an issue, make dispelling lifebloom no longer refund mana and/or life.