Fall Flowers: Crape Myrtle, Dahlias, Salvia & Lespedeza

Bountiful fall dahlias shine in the cool weather.
Bountiful fall dahlias shine in the cool weather.

What a glorious time of year! Summer is over and autumn is here. The garden is still looking good with lots of color from summer annuals that are still going strong, and at the same time there are late fall flowers emerging.


While it is too early for fall color, walking through my garden today, I saw the glistening seed heads of Clematis ‘Princess Diana’.  I consider the beautiful seedheads an added bonus to growing Clematis as the plants provided a show of flowers in the summer. And thanks to the summer heat, Crape Myrtle (Lagerstroemia hybrid) has never looked better. I have noticed that this late-season bloomer has been putting on quite a show throughout the metro Portland area. Several gardeners have confirmed my thought that the summer heat is the cause and have told me their plants have never been more profuse in bloom than they are now.

The flower clusters of Thunberg's Bush Clover almost weep in a shower of pink.
The flower clusters of Thunberg’s Bush Clover almost weep in a shower of pink.


This is the time of year when dahlias are at their peak of bloom. They have become a ‘must have’ in many gardens because of their late bloom time. There is such a large array of flower sizes, shapes and colors to choose from that I think there is a dahlia for almost every garden. There are tall types (up to 6 feet), dwarf types (reaching just 12 inches in height) and all heights in-between. Dahlias also make excellent plants for containers.

After the fall show, dahlias must be dug or protected. In our climate, dahlias should be cut to the ground after a frost. Making the cut slightly below the soil surface will tend to eliminate the chance of water freezing in the hollow stem. If the tender tuberous roots are left in the ground, mulch the soil with 4-6 inches of Black Gold Garden Soil for winter protection. Since we can never predict how cold our winters will be, if there is a particular dahlia that is a favorite, I would recommend digging it up for indoor storage. Once the stems are cut to the ground, carefully dig tubers, rinse off any soil, let them dry and then store them in a box filled with Black Gold Perlite and place in an unheated garage.


I think all gardeners like to try new plants, and the summer annual Salvia ‘Dancing Flame’ was a new plant for me this year. I started with a small plant in a 4-inch pot in April and put it in a pot on our deck. The leaves are speckled gold and green, and during the summer when it was not in bloom, it was a striking foliage plant. Now it has completely filled the pot and is sending out orange/red flowers that are a delight for hummingbirds. I will definitely grow it again next year.

Salvia‘Dancing Flame’ is a bright, beautiful annual beloved by hummingbirds.
Salvia‘Dancing Flame’ is a bright, beautiful annual beloved by hummingbirds.

Bush Clover

A very reliable fall blooming shrub in my garden is Thunberg’s Bush Clover (Lespedeza thunbergii). At this time of year it is in full bloom with clusters of pink sweet-pea-like flowers hanging on arching stems. The broad, tall shrub tends to be floppy, so I have mine contained in a square, wrought iron structure. Even though it’s woody, I treat bush clover like a herbaceous perennial; once winter arrives, I cut it to the ground. (In just one season it will grow to 8 feet!) It thrives in full sun and makes a very good late-blooming summer shrub for the back of a flower bed.

Fall Cover Crops

It has been a banner year for many summer vegetables, and as plants are removed, consider planting a cover crop instead of leaving the soil barren during the winter. Cover crops are available at garden centers and usually consist of several different varieties of seeds including vetch, Austrian field peas, crimson clover and fava beans. Establishing a cover crop is a very easy procedure and can provide an excellent way to turn heavy clay soil into something more desirable for your vegetables to grow in. Once the old plants are removed, add several inches of Black Gold Soil Garden Compost Blend and lightly rake into existing soil. Sow seeds and once again, rake lightly. Cover plants will grow during the winter and even spring. Prior to planting vegetables the following season, they should be tilled under. The foliage will then decompose and fortify the soil. Since many cover crops are legumes, the roots also add nitrogen to the soil.

While there are many things to do in the fall garden, take some time to reflect on the past season and what you liked and didn’t like. If plants need to be removed or moved, this is a good time of year to do it. It’s also a great time to visit a garden center and buy a fall-blooming plant or some choice bulbs for spring.

Just relaxing in the fall garden serves as a reminder of warm seasons passing and the cool season approaching. Before the warmth disappears, enjoy it to its fullest!

Clematis seedheads eventually become fluffy and dry in late fall.
Clematis seedheads eventually become fluffy and dry in late fall.

About Mike Darcy

Mike lives and gardens in a suburb of Portland, Oregon where he has resided since 1969. He grew in up Tucson, Arizona where he worked at a small retail nursery during his high school and college years. He received his formal education at the University of Arizona where he was awarded a Bachelor of Science Degree in Horticulture, and though he values his formal education, he values his field-experience more. It is hard to beat the ‘hands on’ experience of actually gardening, visiting gardens, and sharing information with other gardeners. Mike has been involved with gardening communications throughout his adult life. In addition to garden writing, he has done television gardening shows in Portland, and for over 30 years he hosted a Saturday radio talk show in Portland. Now he writes, speaks, gardens and continues to share his love of gardening. To be connected to the gardening industry is a bonus in life for Mike. He has found gardeners to be among the friendliest and most caring, generous people. Consequently, many of his friends he has met through gardening.

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