Advice on getting nutrients into flowerbed

What's the best way to get nutrients back into a flowerbed that has loads of spring bulbs in it?

When the summer annuals in my flowerbed die off I plan to plant voila & winter pansy's to have a bit of colour over winter & come spring I get a nice display of spring bulbs & as they die off I then plant annuals for the summer so I cant really dig in a load of manure.

Should I rake in a mixture of granule plant food & blood & bone or is there a better way to feed the bed?

 

If you can source some, 3yr old leafmould or other well composted organic matter. Apply as a 25MM layer on the surface before the bulb shoots emerge.Think bluebell woods or ancient wild daffodil terrain. Feed the soil, not the plant.
Would have used slug pellets when they were effective but now, useless.