It doesn't really matter what fertilizer you use but use something that is well balanced and has micronutrients. As your plants are established, you can start fertilizing them now - plan 3 - 4 times in a growing season: spring when they start to grow, early summer, and late summer, with at least 4 but no more than 6 weeks in between each feeding (for me, that would be now, mid June and the last of July/first of August because I fertilize every 6 weeks). Don't fertilize in the fall as that may encourage your plants to put on new growth just in time of a hard freeze.