Depends which plants you mean - if you're talking about summer bedding (petunias, geraniums, that kind of thing) then yes, feed with that weekly, particularly in containers. If you mean shrubs, etc., in the ground, they're best fed in spring, and not too often, and definitely not past mid July.

I would only use that feed early season before blooms form. For flowers, you need a fertiliser opposite to that, ie 8-16-24, where 8 is N, 16 is P, 24 is K.