The Magic of Sweet Autumn Clematis

Written by: Ruth Sens, Weld County Master Gardener 

There is a plant that reigns over my Greeley garden this time of year and it is a clematis vine. More specifically, Sweet Autumn clematis vines (Clematis terniflora) faithfully provide wonderful masses of fragrant creamy white blooms the first week of September. This plant absolutely lights up my tired late-summer garden with much needed beauty and fragrance when most everything else has stopped blooming. 

Sweet Autumn clematis produces masses of fragrant white blooms in the early fall (photo by R. Sens).

The early and mid-summer blooming clematis vines with the larger blooms get serious adoration from gardeners. I do have them planted in my garden also but this clematis is my favorite. Reasons to love this vine include the attractive green leaves in summer, the stunning amount of beautiful blooms, the wonderful fragrance, and the fact that it is a fast growing vine.

The fragrant white blooms awaken the late-summer garden (photo by R. Sens).

You can plant it now but spring planting is optimal. Choose a spot where you will be able to see the mass of flowers and enjoy the fragrance in late summer. Although some sources suggest it will bloom well in part shade, Sweet Autumn blooms most prolifically for me when planted in full sun. This clematis likes a location where the roots can be kept cool in the shade of other shorter garden plants. Dig in some compost when planting, mulch, and then keep the soil moist but not water logged. Sweet Autumn clematis may take a few years to become fully established and winter watering is advised.

The fast growth (15-20 feet per year) means it requires a strong trellis and/or support that it can twine on. Feature it in your perennial garden on a strong accent trellis, on an arbor, a pergola, or even along the top of a chain-link fence. Gorgeous! The flowers will turn into fuzzy seed heads that I think look beautiful in the winter landscape.

Sweet Autumn clematis is a vigorous climber, so provide it with support or a structure (photo by R. Sens).

These vines bloom on new growth so can be pruned to produce optimal blooms. They thrive after a heavy pruning in spring, cut down to 12-18 inches when new green shoots start to emerge. This can be a physical workout if the plant has gotten large, but then you can stand back to watch in amazement as it grows and blooms again. Plants established in optimal conditions can live up to 20 years.

Of note, Sweet Autumn is considered invasive in several Eastern states. It is not listed on the Colorado Noxious Weed list. 

This should be an easy decision if you have the right spot and want a gorgeous large vine. Plant and enjoy! Refer to this University of Wisconsin Extension publication for more information. 

Shazam! Plants that Shine in Fall

Posted by: Alison O'Connor, Larimer County Extension

It's always around this time of year when I look around the garden and have a hard time finding anything that makes me swoon. Most plants just look a bit....tired. Like their gardener. The iris have flopped. The coneflowers are fading. The annuals are waiting for the first frost. But looking a bit closer, you find certain plants that are just ramping up for the fall.

Here's a (very short) list of some of my favorites, but please share the ones you love.

We have to kick it off with ornamental grasses. These tough, beautiful plants really make you turn your head in the fall with colorful foliage and flowers. There's a great ornamental grass for any landscape and there's a national study where CSU is a partner with numerous other sites across the U.S., looking at various species of ornamental grasses. Fellow CO-Hort Jane Rozum did her Master's work looking at water use of these plants.

Two of my (current) favorite ornamental grasses are Blonde Ambition blue grama (Bouteloua gracilis 'Blonde Ambition') and Shenandoah switchgrass (Panicum virgatum 'Shenandoah').

Blue grama is a native of Colorado and Blonde Ambition is a selected variety. The dancing "mustaches" (or eyebrows) gently bob on top of delicate foliage. It's so freaking cute, I can barely stand it. I love this grass. I planted three in my yard last year, so they are still pretty small. One worry I have is this is being planted everywhere. Even in the Costco parking lot islands. Will it become the next Karl Forester?

There's a lot going on in this photo, but Blonde Ambition is in the middle with the straw-colored "mustaches". To the left is orange carpet hummingbird trumpet; behind is Paint the Town shrub rose; to the right is  blue fescue.

Shenandoah is stunning. The foliage turns burgundy-purple as cooler weather sets in. The dainty pink flowers sit atop the plant, which will reach about 3-4' tall at maturity. It's fabulous. I adore this grass. It's a great size, tough as nails and is pest-free. I made a "happy accident" (thanks, Bob Ross!) and planted it near a sedum that picks up the pink inflorescences.

Nosy Maple is sniffing out the sedum and Shenandoah switchgrass. The foliage will continue to develop a deeper burgundy color as fall progresses. 

Two vines really shine in the fall. One is Sweet Autumn clematis (Clematis terniflora), which is a vigorous grower and has tiny white flowers that cover the plant, like a blanket of snow. My Sweet Autumn died back to the ground during winter and went nuts this summer, covering the pergola it's planted by. Bonus--it smells nice, too!

Sweet Autumn clematis. This is a nice clematis to plant, since it blooms so late in the summer, unlike some of its cousins. 

The other vine that deserves a nod is silver lace vine (Polygonum aubertii). Now, this plant isn't for everyone. It's very aggressive (borderline invasive) and can quickly cover any territory it's planted near. This one happens to be on our corner fence....but every spring I have to yank, pull, prune and hack to tame the vines. I once peeked through the fence and it's growing a good five feet into my neighbor's back yard. So plant with caution, but if you have the space, you'll enjoy the fall show!

I think it's safe to say that the silver lace vine has pretty much eaten the fence. Pretty though!

Finally, many sedums bloom late in summer and have attractive flowers and foliage that jazz up the fall landscape. Angelina sedum (Sedum rupestre 'Angelina') is lime green during spring and summer and turns copper with cooler weather. What I love about this plant is how it finds pockets of bare earth and gently fills in to form a dense mat. I noticed that the wet spring caused some of the plants to die out, but they will recover next year.

Angelina sedum. The lime green foliage turns copper with crisp fall weather.

A larger, more upright sedum with variegated foliage is Frosty Morn sedum (Sedum erythrostictum 'Frosty Morn'). This plant was covered in honeybees and other pollinators--it was a heyday. Reaching about 18" tall, the stout flowers are so large, you wonder how the plant can stay upright. But the variegated foliage and pink flowers are a wonderful compliment to each other.

Frosty Morn sedum. I love variegated plants...and the color pink. What more could I ask for in a plant?

There are, of course, many other plants that are spectacular in the fall...phlox, mums, Joe-pye weed and more. These are just a few that caught my eye as I looked around my tired garden. Why is it that my good plants are fading, but the weeds are healthier than ever?!