What a shame you have to give up 15 feet, but nice way you've decided to use it!

First of all, to me that image looks like it's been cut-and-pasted together. I don't know where it is, but here in my zone 7, some of those things just wouldn't be blooming at the same time. And you certainly cannot expect to have perennials blooming all season long ... even a short one ... as they tend to bloom for only 4-6 weeks before going into a resting phase.

You could do something like that with annuals, since they bloom all season long, but, of course, you'd have to replant every spring. When I was a child, our neighbor had an annual garden like that - snapadragons, zinnias, sunflowers, celosia, alyssum, and I can't remember what else, rioting along the back wall of their home. It was glorious.

So that it doesn't look forlorn in the "off" seasons, you might consider a mixed shrub and perennial border, with some bulbs thrown in for good measure. Choose some great shrubs for the "bones" to give structure and interest to the border year 'round. Then start adding perennials and hardy bulbs, selecting them to give a succession of bloom from early spring through late fall. Be sure to consider leaf color and texture, as these will give interest to your garden even when not in flower, and can complement and highlight the ones that are in flower.

Having lived in zone 7 all my life, I hesitate to make any suggestions for your zone, but would suggest there are numerous books and websites that can help, and the most helpful might be a visit to a local public garden to see what performs well and plays well together. Of course, taller plants in back, shorter ones toward the front, but try for lines that undulate in height and from front to back to avoid a stair-step look.

FWIW, one of my borders, in half sun, has blooms from February through November with snowdrops (galanthus), daffodils, grape hyacinth, tulips, creeping phlox, perennial candytuft (ibiris sempervirens), tradescantia (which is wearing out its welcome with its spreading habit), peonies, irises, baptisia, roses, hardy geranium, cultivated daylilies (not hemerocallis fulva, the invasive orange "ditch lily"), false aster (kalimeris) 'Genghis Khan', garden phlox ('Davidii' and 'Franz Schubert', fairly resistant to powdery mildew), threadleaf coreopsis (either 'Zagreb' or 'Moonbeam' ... can't remember), nepeta, bee balm (monarda), obediant plant (physostegia) 'Miss Manners' (she reseeds less prolifically), New England aster 'Raydon's Favorite', Montauk daisy. There's a blue rug juniper for winter interest, two different flowering weigelas ('Wine & Roses' and 'Rubidor'), and at one end a mature redbud (cercis canadensis), at the other a passionflower vine (native passiflora incarnata) climbing the lamp post. Probably have left someone out ... sorry, guys. I will confess to also having a variegated euonymus (alien invasive ... days are numbered), just removed a Japanese spirea (another A.I., and it's neighbors responded with wonderful growth this spring), and a few years ago removed a red-leaf Japanese barberry (another A.I.). Where it wraps around into shade, the bed transitions into to shade plants ... but that's not what you need.

That border did not happen all at once; it evolved over the years and, as you can tell, is still evolving ... Well, that's the whole point of gardening, isn't it? After all, I've heard it's been called the slowest of the performing arts.

agardenstateof_mind gave you plenty to chew on and consider. I'll add that for suppressing weeds/grass where you don't want them consider laying down recycled corrugated cardboard (available free from grocery/liquor stores) and topping it with bark mulch. Worms love cardboard. Where they like to be, they poop. Worm castings (poop) are the best organic fertilizer going (not to mention free for the pooping).

My garden is filled with lots of perennials in order for me to achieve the look I wanted for as many months of the year as possible. I'm in Zone 6, southern New England. There's something blooming in my garden from March to November every year. Mine is a mixed bag of perennials and shrubs as well as the bulbs my mom & brother planted 40+ years ago.

A good place to start learning about perennials that are hardy in your area, see if you can check out 'The Well Tended Perennial Garden' by Tracy Desabato-Aust from your local library.

There are lots of knowledgeable gardeners on this forum so don't hesitate to pick our brains when you stumble. Good luck!

While irises are a noble flower, I no longer plant them. Haven't for 20 years. They are OK when blooming, but here in north Missouri that's only 2 or 3 weeks out of 52. The rest of the year, what have you got? Nothing but green fronds. And if grass starts creeping into your irises, you're sunk. You have to hand-pull it. Endlessly.

I have to agree with littlebug vis-a-vis irises. I only have one or two but I'm not impressed after watching them the past 5+ years. I do love my Siberian irises however. I have both blue and pure white I grew from seeds via winter sowing. The blooms this year were gorgeous (sorry--no photos) and the clumps are generous so there are multiple blooms on each. I have clumps growing on the east, north and west sides of my little green acre and all of them are amazing every year.

Have you read through this thread on creating a garden in front of a fence? It has lots of photos and advice.

To keep out grass you first want to remove it or kill it, and then put a deep edging between the garden and the grass, in your case back under the fence. When grass is removed before planting and the garden is well-mulched, you won't need to de-grass at all. I have 3 really large beds and do very little weeding as long I keep a good layer of mulch on them. Right now one needs renewing because I am beginning to see weeds.

While you won't ever get photos like your inspiration photos since many of the flowers are cut/paste with things that don't bloom together IRL, you can create a colorful and richly textured garden. Use a mix of bulbs, perennials, and shrubs and choose plants that either have a long bloom time such as Hydrangea paniculata (Quickfire blooms for me from early July until whenever we have a hard frost in October) or interesting foliage to carry the plant when not blooming such as ninebark/Physocarpus which comes with various shades of red or gold foliage or Amsonia hubrichtii, which follows the powder blue spring flowers with feathery summer foliage and bright gold autumn folliage that contrasts well with most other perennials. Have some combination of shrubs for winter interest, either branches like dogwoods and Japanese maples, or evergreen (broadleafed such as rhododendrons or needled like false cypress/Chamaecyparis), or bark such as paperbark maple/Acer griseum.

You will want to figure out how much sun and shade you will have once the fence is installed in order to figure out what will thrive there. So spend time looking at how shadows currently fall, and think about where the sun is in relationship to the fence and the garden. You could even use a large sheet of cardboard as a fence panel mock-up to see how the shadows will fall, remembering that the sun is highest in the sky in June and that the shadows will lengthen both before and after June 21.

Be aware that the garden will look sparse for the first year or two, but leave room for plants to fill in. You may find this Before and After thread useful to help appreciate that.