A boisterous flock of honking Canada geese flew over our roof the other night. The noise woke us and the cat who sat upright with uncharacteristic interest staring at the ceiling. She seemed to be taking note of the seasonal reminder that summer is waning — and you-know-what is on its way — only to burrow more deeply into the covers. There have been signs all around, The buddleia out front has been a’flutter with Painted Ladies and Monarchs for weeks now. No doubt these delicate little travellers are tanking up for what’s to come, just like those geese practicing their night flights. A yellow leaf flutters to the ground, here and there. Sigh…indeed all are signs of the times.

In this season when most of the perennials have finished up their one-act performances, the annuals pretty much have bloomed themselves out and the vegetable garden is but a shadow of its former self, it is decidedly a lazy time of year for the garden. It can also be a color-less one in this transition period before the trees stage their fall foliage extravaganza for the visiting leaf peepers and all, unless someone has planned for fall-blooming and showy fall plants and even a second-season crop in the vegetable garden.

Aside from the ubiquitous mums (not that there’s anything wrong with them!) and the blaze of asters, the ornamental border can still flash with color and interest thanks to a few plants that might have slipped under your radar. If you don’t have these choice selections, this could be a great time to add them, especially if you can find them marked down for seasonal clearance at area garden centers.

Fall is a good time to establish new perennials and shrubs too. Just remember the principles of providing rich soil well-amended with compost in the planting hole and regular watering until the ground freezes to get them off to a good start and prepped to hit the ground running next spring. I also like to start out with a root-stimulating concentrate mixed with water when planting, and then used once a week for two to three weeks after that.

• Fall-blooming hostas, those in the Hosta plantaginea group offer not only pristine white blooms, but also the unique distinction within that huge family of hostas of possessing hauntingly-beautiful fragrance. The oversize blooms brighten up the shady bed where all the other hostas completed their bloom time weeks ago. The late-blooming group also tends to be less susceptible to slug damage for some reason, yet another reason to add them to the shady garden.

• Another late-blooming hosta, ‘Autumn Frost’ is one of the new line of almost bullet-proof perennials from Proven Winners. This diminutive hosta grows to about 10 inches tall, making it a good addition to rock gardens. Its luxurious pale lavender blooms add a sweet touch of fall color over top of the silvery-green and cream foliage. Also look for ‘Diana Remembered’ (from Terra Nova), another late-blooming hosta with variegated foliage.

• Heucheras, also commonly called coral bells, have come a long way since Miss Mary counted hers all in a row. (All right, I know she actually counted cockle shells.) New innovative varieties from Terra Nova Nurseries light up shaded gardens from spring through the fall with foliage colors that give even Mother Goose a run for her money. Whether it is the subtle shades of ‘Ginger Peach’ or ‘Sweet Tea,’ the lusty reds of ‘Galaxy’ or ‘Fire Alarm,’ or the yellow gold of ‘Solar Power’ or ‘Sweet Tart,’ Heucheras prove that you don’t need flowers to provide color. And there are the new trailing varieties, such as ‘Sunset Ridge’ which take the color treat and spread it around. Plus Heucheras do it all in the shade with no slug damage.

• While we’re on the topic of plants for the shade, don’t forget the bronze foliage of Rodgersia ‘Bronze Peacock,’ the darkest of any with thick, deeply-veined glossy leaves. A bonus are the dainty pink flowers in the spring, a stunning combo with this perennial's huge, tropical-looking leaves.

• Moving into the sun, we know that fall is when sedums earn their keep. But don’t settle for yesterday’s sedums. This is one bullet-proof perennial that has undergone a complete transformation because we don’t want no stinkin’ floppy ho-hum, yesterday’s-news sedums! New varieties produce upright deeply-colored foliage and brilliant flower heads. Look for the compact ‘Cherry Truffle’ which is new for 2012, as well as ‘Thunderhead,’ with rich deep-rose flower heads. Other choices include ‘Chocolate Drop,’ ‘Raspberry truffle’ and ‘Dynamite,’ a short and dense Sedum. All are hardy to Zones 4-10, and these varieties are from Terra Nova.

• For extra punch, combine any of the above sedums along with any of the new Spireas such as ‘Double Play® Gold’ or ‘Double Play® Big Bang,’ (both with vibrant foliage) is in for a treat of contrasts in color. Like all Spireas, these are cold hardy to Zone 4, and their fine foliage can be easily trimmed to shape. They are ColorChoice® shrub selections from Proven Winners.

• Or consider the pale-gold fountain-like growth of the beauty bush (Kolkwitzia amabilis) ‘Dream Catcher’, another shrub with year round interest, producing clusters of pale pink trumpets in the spring. Also, hardy to Zone 4.

• Another color-play in foliage can be found in the new Weigela introductions ‘Fine Wine®’ ‘Spilled Wine®’ with dark, dark red foliage or ‘Wine and Roses®’ or the fantastic new miniature Weigela ‘Midnight Wine®’ that tops out at about a foot tall by two feet wide. Just imagine how this one can provide not only structure to the sunny bed, but also sensational color. Here again, pair these dark ColorChoice® shrubs with a chartreuse or golden contrast like the two choices above or something like Hakone grass for a traffic-stopping presence.

• Japanese anenomes take the end of the summer and run with it. Both the pink and the double-white blooms are elegant additions to those perennial beds. This is one perennial that tolerates some shade, adding color when it is needed most.

• Every September my Sweet Autumn clematis blankets the lilac tree on which it grows with drifts of fragrant little white “snowflakes” of blooms. The bees and bumblebees seem to enjoy the display almost as much as we do. Unlike all the other clematis varieties that bloom from the late spring on, Sweet Autumn spreads its display as autumn arrives. A word of caution is warranted here: Sweet Autumn clematis can become something of a thug and should be planted where it has a sturdy support and won’t be able to overrun nearby plants and shrubs.

• Crocosmia is a bulb flower that blooms late summer with drifts of sizzling orange flowers. Give it a protected spot in the sunny garden and this one will slowly spread its warmth, flowering just when you thought everything else had played out. These are available from Old House Gardens Heirloom Bulbs.

• Dahlias are the patient gardener’s reward. These tender tubers must be stored over the winter, started early in the spring in containers and set out not-too-soon and not-too-late and cared for all summer. But come late summer and it’s shut-the-door! One worth mentioning is an heirloom that has been around since 1927 and for good reason. Bishop of Llandaff sports positively eye-popping, burgundy, cut-leaf foliage all season, and then to top things off, scarlet blooms sparked with vivid-yellow stamens. If that’s isn’t a garden statement, I don’t know what is. Find this and other time-worthy, garden worthy heirlooms from Old House Gardens (oldhousegardens.com).

• Gentian is (Gentiana andrewsii — Bottle gentian, Closed gentian, or Closed bottle gentian) is a native plant worth adding to rock gardens and sunny borders, though it will tolerate a small amount of shade. The definition of the bluest-blue, Gentian blooms late in the season often staying “in flower” with its curious true-blue, bud-like blooms through October.

• Proving that you don’t need flowers for color, consider ornamental cabbages. These inedible cabbages possess the most colorful and textural foliage of all the fall-planted annuals. Brilliant floral colors and shapes, even metallic sheens and elaborate textures, are displayed with gusto in these cold-hardy plants. Pair them with any of the above perennials or shrubs and let the sparks fly. Their edible cousins and all those plants in the Cruciferous family (cabbages and kales and the lot) are coming into their own in gardens. Several greens and leaf lettuces are good choices for the fall garden, as are leeks and too, this is also the season to plant garlic. Parsnips benefit from a bit of cold which sweetens them up and beets reward with tasty green tops as well as luscious tubers.

Nature abhors a vacuum, and the time is ripe to fill one with color and interest. This is not time to stand by or sit on your laurels. The cat knows and is getting ready. Why just the other evening she actually climbed up into my lap for a little snuggling, a sure sign that cooler weather is coming.

Lynette L. Walther is the recipient of the Garden Writers Association’s Silver Award of Achievement for 2012, National Garden Bureau's Exemplary Journalism Award and the Florida Magazine Association's Silver Award of Writing Excellence. She is a member of the Garden Writers Association, and she gardens in Camden. Got questions, or comments? Visit her blog, and join in the conversation at: gardeningonthego.wordpress.com or “friend her” on Facebook.