Any reputable agronomist will tell you that if you garden where the soil has not been compromised (mining/waste tip/oil spill/chemical spill - you get the idea) then you do not need to fertilize perennials. If you are growing vegetables - that's a whole other thing. You may choose to add something to the hole when planting bulbs.
I have never fertilized my perennial garden in the 40+ years we've been here and it is still as 'productive'
