Gardening in the Twilight Zone
September 9th, 2025
Warning: We are about to enter the Twilight Zone.
How does your yard look as the sun starts to set on another season?
No, not the Rod Serling version but that time of the gardening season between peak plant performance and that final, glorious blast of fall foliage.
It’s a time when little might be going on in the yard – if you haven’t planned for interest now.
In that case, you might be looking at more of a black hole than a twilight zone. That’s especially true in yards with little diversity.
I suspect the reason for this September dearth is because most people plant-shop in May when the gardening hormones kick in. And that means yards get loaded up with things that look good then, such as azaleas, rhododendrons, lilacs, dogwoods, peonies, and the “safe time” to plant summer annuals.
A homely little beautyberry bush that won’t produce its stunning sprays of metallic lavender berries until September is no match in May for an azalea’s bright rosy-red, big-bang-ball of color.
A bag of shriveled brown hockey pucks called “dahlias” can’t compete with the fist-sized blooms of a peony plant.
And crape myrtles haven’t even leafed out yet in early May while the dogwood blooms are more alluring than a doughnut shop to a dieter.
It’s unfair competition. If beautyberries had antitrust lawyers, they’d no doubt sue.
One way to brighten the dog days of late summer is to plant more variety. If you plant enough different things, you’re bound to end up with at least a few plants that look decent down the home stretch.
Plant-shopping at this time of year – at the beginning of fall planting season – is another good way to turn the tables on the competition.
This is when the dahlias look great and the peonies are looking ratty. It’s when the asters and goldenrods are in glorious bloom while the lilacs are dropping leaves from powdery mildew.
A third strategy is planning for home-stretch interest no matter when you buy.
When you stop and think about it, there’s actually a lot of potential beauty to tap into these next six weeks. The choices fall into five categories:
1.) Plants that peak during the Twilight Zone. Some plants are naturally late to show off their stuff. Best known is mums, but sedum, asters, goldenrod, native ironweed, turtlehead, and Japanese anemone are six other perennial flowers that bloom late summer into fall.
Aster ‘Purple Crush’ peaks in late summer when most other flowers are calling it quits.
Two lesser-knowns worth considering are leadwort (a.k.a. hardy plumbago), which is a low, spreading groundcover that blooms cobalt blue in late summer and then gets glossy scarlet leaves in fall, and Mexican bush sage, a type of tender salvia that sends up a forest of late-season purple spikes.
In the woody world, vitex is an eye-grabbing, late-summer flowering shrub with blooms that resemble butterfly bush, while the blue mist shrub (Caryopteris) is one of the latest-blooming shrubs, flowering in powdery blue or blue-purple on a 3- to 4-foot silver-leafed ball.
Other late-peakers: dahlias, liriope, perennial sunflowers, tricyrtis, boltonia, and “naked ladies” (Lycoris).
2.) Plants that rebloom at this time of year. Especially if you’ve cut back or removed spent flowers earlier, many plants will rebloom in the Twilight Zone.
Roses are a prime example of a plant that mainly blooms in June but that gives a smaller encore show in September. Catmint, yarrow, salvia, and hardy geraniums are four perennial flowers adept at second winds.
Breeders also have been giving us new varieties of old favorites that have been found to rebloom. The ‘Endless Summer’ line of reblooming hydrangeas is the best known, but we also now have a nice selection of reblooming daylilies, iris, azaleas, spireas, and weigelas.
Other home-stretch rebloomers: gaillardia, spiderwort, beebalm, coreopsis, scabiosa.
3.) Plants with great late-summer and early-fall fruits. Fruits and berries add a whole new color dimension from here on out. The aforementioned beautyberry is the best of the little-known examples, but we also have red and gold berries from both evergreen and winterberry hollies, orange berries of pyracantha, and a host of berry colors on various viburnums.
These are the ripening late-summer fruits of viburnum Brandywine.
Credit: Proven Winners
Other home-stretch fruiters: Kousa and American dogwoods, hawthorn, cotoneaster, inkberry holly, yew, Japanese plum yew, juniper, Oregon grape holly, chokeberry, St. Johnswort, ornamental hot peppers, and some roses.
4.) Plants with colorful foliage all season. Some plants are grown mainly for their colorful leaves that stick around until frost turns them to mush.
These would include dark-leafers such as some varieties of coralbells, ninebark, and hardy hibiscus; golden-foliage plants such as golden Hinoki cypress, golden junipers, and golden oregano, and variegated plants such as variegated weigela, variegated liriope, and several varieties of euphorbia.
Other colorful-leafed beauties: foamybells, ligularia ‘Britt-Marie Crawford,’ dark-leafed cimicifuga, Japanese maple, purple beech, purple or gold smokebushes, purple or gold redbuds, blue spruce, goldthread falsecypress, golden spirea, abelia ‘Kaleidoscope,’ elderberry ‘Black Lace,’ blue-tinted fothergilla, variegated hydrangea, variegated red-twig dogwood, purple and gold St. Johnsworts, variegated brunnera, Japanese painted fern, pulmonaria, golden yucca, and several ornamental grasses (little bluestem, red switchgrass, golden forest grass, etc.)
5.) Plants with endurance. These are long bloomers that don’t know when to quit. They start blooming in summer and keep going, and going, and going.
A lot of annual flowers fall into this category. So do a few energetic shrubs such as some shrub/landscape roses, crape myrtles, and panicle hydrangeas.
But most are perennial flowers, including: lamium, agastache, verbascum, phlox, heliopsis, Russian sage, black-eyed susans, and Joe Pye weed.
Now you’ve got some ammunition. And no excuse not to take the mystery out of the Twilight Zone in your yard.