We've got a bunch of long-blooming summer-fall perennials planted about as close as you can get away with to each other. Not right up against each other, but as much as we could get in there. Black-Eyed Susan Goldstrum and Goldster, Becky Shasta Daisies, Echinacea, E. Friesland Purple Salvia, Catmint, Hidcote and Provencal Lavendar, Liatris (Gayfeather), Smooth Aster Blue and Raspberry, Coreopsis, Snowcap Shasta Daisies, etc. Which spring flowers would you plant between the perennials?

We have a dedicated bulb flower bed with crocuses, hyacinths, tulips and irises, but we realized that the perennials areas will look pretty bare all spring, with just dark mulch with only the first perennial leaves popping through at some point.

Also will it be a problem providing Espoma bulb food AND Espoma Plant food to the same bed? Should we put the bulb food in the hole with individual bulbs?

I wouldn't worry about tailoring fertilizer to bulb vs plants. Skip the bulb food since you are fertilizing for perennials.

A nice early spring bulb- Grecian Windflower, will have small sort of ferny leaves and early flowers, then goes away nicely before perennials fill out. Some Iris are very early and small. Snowdrops are very early.
Just trying to suggest some you don't have in the other bulb bed, and that won;t have too much foliage laying around for weeks.

If this is a sunny bed you might plant fall pansies and have them live thru winter, blooming whenever it is mild, and nicely in early spring till too hot or crowded out. (I do that every fall with a sunny bed)
Or get the pansies or johnny jump ups as soon as they are sold in spring. Or primrose sin spring.

Thank you. One of the areas is under a tree canopy and partly sunny, mostly morning and later afternoon and early evening sun. Sunny enough for Black Eyed Susans Goldstrum and Goldster, Becky Shasta Daisies, Coreopsis, Aster and Echinacea to flower decently enough, but not to their full potential which I see in other areas in the backyard which get more hours of direct sun.

The other areas in the backyard have plentiful direct sun.

I would certainly give Giant Pansies a try. Haven't ever seen them blooming in winter in this area growing up, but that doesn't mean they wouldn't - only that I didn't see people nearby growing them. (Though they have been a staple for us in Northern California in winter).

If we did go with the crocuses, hyacinths and tulips, I'm guessing their green foliage which stays up after won't be noticed much once the perennials are growing up around them.

Yes, people do use spring bulbs and let the perennials hide the aging leaves. Hyacinths seem very easy for me.. I planted forced white ones and they've actually made more than one bloom stalk per bulb I started with.
Daffodils tend to multiply and their leaves last a long time.. still, you might push them behind the perennials.
TUlips tend to NOT last a long time or multiply.. old fashioned reds can live a long time, and I have Gavota purple and cream ones that have bloomed a number of years. Species tulips are I think earlier and more petite.

I have a mix of dwarf Daffodils.

Yes the Iris leaves last a maddeningly long time, even longer than the tulip leaves. We hid them with Wave Petunias planted in May. We have daffodils with the tulips, forgot to mention them.

We have some tulips and crocuses that come up every year that were planted +20 years ago. They are shorter early-mid short reds with yellow centers. Even when we planted +300 new bulbs in 3 layers around them they still came up.

Will it cause any problems for the summer-fall perennials to have tulip bulbs planted between them? Will it limit the perennials' growth?

Has anyone here had Giant Pansies blooming in coastal NY winter weather December-February? We'll definitely give them a shot, but likely also plant bulbs, as one shouldn't interfere with the other.

it could be a little colder for you than me, re the pansies.. And have mine in a southfacing bed that I am sure is a zone warmer than supposed to be, due to the exposure. So unless someone can answer that, blooming in winter may not happen for you at all.

Treesong, I don't know if the following is of any use to you, since I only know about herbaceous perennial gardening in our zone (5b).

I do maintain all of spring-, summer- and fall-blooming perennials in the same perennial beds and aim for blooming throughout the growing season. The plants are relatively closely placed in the flower beds and I find mulch just gets in the way of ongoing maintenance. I avoid species and cultivars that spread vigorously, including a number of those you mention. Despite that, some reduction in the spread of some summer- and fall-bloomers is often necessary, for me, at the end of the fall. I'm continually cutting back perennials that have bloomed from summer on. I believe that it's especially important to do this in early Fall; the latter to expose (to sun and rain) spring-bloomers that have spent the summer protected underneath taller summer-blooming plants.

Spring bloomers which have worked well in our garden (viz. at least here) include lungworts, primulas (Polyanthus type) and brunnera. I've also added hellebores more recently. A few ephemerals (spring blooming and are then gone) have worked well, especially Virginia bluebells. I find the spring-flowering anemones I've used (Anemone ranunculoides and A. robinsoniana) get to be spread around too much for my personal liking.

Re spring bulbs: currently I only add the first to bloom; namely, snowdrops (not eaten by the voles)..

Approximately the same location in the flower bed:
(1) May 3, 2021 (Fall monkshood at back).

(2) Aug 7, 2021 (same Fall monkshood at back)
(Peonies on either side at the back.)

I'm in the city but last year I had a johnny jump up in a pot with a daylily (not planted but a seed got in there somehow) that bloomed all winter. And not just a bloom here or there. Lots of blooms! Even after heavy snow and hard freezes with no snow cover it kept on blooming. It finally died this summer. This was the first time I ever had any pansy or violet (besides wild violets) survive the winter.

I do have lots of snapdragons survive the winter. They bloom fairly early in the Spring so you might consider those too. They might even reseed for you.