I too thought the bloom a bit paler than expected. Consider organic fert rather than chemical. Like those fish and kelp-based things. Chemical ferts hit the plant with all of their fert when they're applied. That's why their numbers (as in 20:20:20) are so high.

Legally, they have to state the max fert the plant will recieve at any moment. They happen to deliver it all in the first moment, and none later on.

Natural ferts are more time release based, so their numbers look like 4:5:2, and seem inadequate for the job, but in fact they do a better job because they release ferts slowly throughout the period between doses.

Go lighter on the fert and don't let the potting mix dry out between waterings. That will concentrate the salts in the leaf tips, and can burn them.

McJulie