Fall Color In The Flower Garden

David Graper
SDSU Extension Horticulture Specialist

The mild fall weather is giving everyone a chance to enjoy an extended and enhanced view of the fall color, not only from our trees but from herbaceous plants as well. Usually by now we have had a hard freeze or two that pretty much kills the foliage and often the stems of our flowers, but so far in many areas, the cold has not been that extreme. The result is a chance to see some of the fall leaf colors in our flower beds that ordinarily we do not get a chance to experience. And, of course, the milder weather means that a lot of our cold tolerant plants are still flowering as well, giving us even more color to enjoy. Here are some of my favorite plants for fall color.

Asters (Symphyotrichum)

Asters (Symphyotrichum) are one of the best fall blooming plants with flower colors ranging from white to pink, lavender, blue, purple and red. They can also range in height from just a few inches to several feet. The flowers are generally quite frost tolerant so we can often enjoy them late into the fall. Late season foraging butterflies often can be seen getting a nectar snack from the asters, long after many other flowers have faded for the year.

Blue Star (Amsonia tabernaemontana)

Blue Star (Amsonia tabernaemontana) and other species have long been touted for their lovely yellow fall color. But, unfortunately we seldom get to see it in our climate. This year they are in their glory, having turned bright yellow in just the last week or so. As you might surmise from the common name, the flowers are blue and star-shaped and appear in late spring to early summer. Plants grow about 24 to 30” tall.

Chrysanthemums

Chrysanthemums have long been one of the primary plants for the fall garden, and they still are a great choice. Be sure to look for cold-hardy cultivars. These will often be available in the spring but more frequently in the fall. If you buy a potted plant in bloom, get them planted into the garden as soon as you can so they have a chance to get established before the ground freezes. If you want to keep it on your deck or front step, that is OK too, but it might become more of an annual plant then. There are some cultivars from the Mammoth™ series that are quite hardy and work well in our gardens. Cut the plants down close to the tiny buds you will see at the crown of the plant in the fall, then apply mulch 2-3” deep, after the ground has frozen to help protect the plants for next year.

Flowering Kale & Cabbage (Brassica oleraceae)

Flowering kale and cabbage (Brassica oleraceae) are one of the true gems of the fall garden with their cabbage like appearance and bright white, pink or red blaze of color in the center of each plant. They look great all summer too but their most vibrant colors do not appear until after a frost or two. The leaves may be smooth-edged like cabbage or extremely dissected, giving them a very lacy appearance. One of my favorites, ‘Redbor’ is a real stand-out amongst the kales, often growing to over 3’ in height. I saw that they used them to line the drive up to the entry gate at the Minnesota Landscape Arboretum – they must have been approaching 5’ in height! The stems are purple, as are the very curly leaves. All of the kales have more vibrant color and sweeter flavor as the temperatures cool in the fall.

Giant Tickseed (Coreopsis tripteris)

Giant tickseed (Coreopsis tripteris) truly is a giant among most perennial garden plants since it often will grow 6-8’ tall by the end of the growing season. Despite its height, it does have a rather fine texture with the fine, trifoliate leaves that it has. During mid to late summer it produces 1” wide yellow flowers. But for me, the best part of this plant is the burgundy fall color. Giant tickseed can become a bit invasive, I think mostly by seed, so deadhead after flowering to help reduce this problem. If the species is too big for your garden, there are some smaller cultivars available. We have ‘Lightening Flash’ at McCrory that has bright, lemon-yellow foliage all spring and summer long. It only gets 3-4’ tall. Unfortunately it does not flower that well and just turns brown in the fall.

Hostas

Hostas might be an odd plant to include in this list, but I think it adds some dramatic character and textures to the fall garden. I find it interesting how different cultivars of Hosta, and there are literally hundreds of them, have varying degrees of tolerance to frost. Some might be completely collapsed after the first frost, while others are just as green as they were a month ago. Certainly part of that is related to the various microclimates that exist in most gardens but it is still cool to see as we make that transition into persistently cold weather in the fall. I particularly like the Hosta that have obviously been damaged by freezing temperatures but have not yet collapsed.

Lungwort (Pulmonaria)

Lungwort (Pulmonaria) is another favorite of mine. It holds up to the early fall frosts and freezes quite well, allowing the spotted or silvery foliage to remain an attention-getter in the shade garden late into the fall. Then, come spring, it puts on a glorious display of flowers that are borne on 8-12” tall flower stalks. The flowers come in white, pink or lavender and last for a few weeks. Then a new crop of the spotted leaves develop which remain until fall.

Ornamental Grasses

Ornamental grasses have been gaining in popularity over the last decade or so. But, I think they are still underutilized, or at least the diversity that is available is still underutilized. I enjoy seeing grasses being used in a landscape, particularly if they are using something more than the over-planted ‘Karl Foerster’ feather reed grass (Calamagrostis acutiflora). There are many other species and cultivars of ornamental grasses to choose from. If you ever get a chance, visit the MN Landscape Arboretum and check out the Ornamental Grass Trials there that Dr. Mary Meyer has had for many years. You will be able to see some of the best examples of grasses for us to use in this region. A few that I particularly like include: Indian grass (Sorghastrum nutans), prairie dropseed (Sporobolis heterolepis) , switchgrass (Panicum virgatum) and flame grass (Miscanthus sinensis ‘Purpurascens’). Each of these are warm season, bunch type grasses so they generally do not spread very much. Most of these are low-maintenance plants too. Once you get them established they will generally not need extra water or attention except to cut them down to the ground in the spring before they start to grow again.

Pigsqueek (Bergenia cordifolia)

Pigsqueek (Bergenia cordifolia) is a great plant from spring to fall, but really becomes accentuated in the garden when the thick, leathery foliage takes on its burgundy-red fall color. Plus, that foliage will remain mostly intact until spring, especially if it has a little protection from the drying winter winds. Then in the spring it puts on its next display of bright pink flowers, but they may also be white. This interesting plant gets its common name from the fact that if you take one of its leaves, fold it over and rub it together you can create a sound something like a pig grunting. So, perhaps it should be called piggrunt instead of pigsqueek?

Sedum (Hylotelephium)

Sedum (Hylotelephium) ‘Autumn Joy’ and other cultivars is a dramatic plant from late summer until we get a hard freeze which finally will turn those stiff stems and dark rose-pink flowers to mush. But for now it is still holding strong. In fact you could still probably use it as a cut flower, if it has not suffered too much freeze damage.

Sedum (Hylotelephium)

Sedum (Hylotelephium) ‘Autumn Joy’ and other cultivars is a dramatic plant from late summer until we get a hard freeze which finally will turn those stiff stems and dark rose-pink flowers to mush. But for now it is still holding strong. In fact you could still probably use it as a cut flower, if it has not suffered too much freeze damage.