Ask Mr. Smarty Plants

Have you seen any fall flowering shrubs around your area, in purple or any other color? And what months do you consider to be Fall? These are rhetorical questions, because when we search on shrubs native to Michigan, blooming purple in September, October or November, we got zilch. When we added August to the bloom months, we got Diervilla lonicera (northern bush honeysuckle), which is a deciduous shrub to 3 ft with dark-green leaves changing from yellow to red in autumn, and small green bell-shaped flowers that become orange-purplish-red, and bloom from July to August. 

Next we tried searching on shrubs on which the bloom period extended into September. We found:

Cephalanthus occidentalis (common buttonbush) - evergreen, to 12 ft. tall, blooms white, pink June to September

Dasiphora fruticosa ssp. floribunda (shrubby cinquefoil) - semi-evergreen, blooms yellow June to September

Spiraea alba (white meadowsweet) - deciduous, 3 to 6 ft. tall, blooms white June to September

Your USDA Hardiness Zone is 5b to 6a, which means that your average annual minimum temperatures will range from -10 to -5 deg. F. Every plant's main task is to reproduce itself; to do this it must set seeds and in order to set seeds it must bloom. So, if a woody plant waits until October or November to bloom, its seeds are going to fall on frozen earth and be very unlikely to survive the winter. Even if you bought a plant, not relying on seeds, there would still be the fact that the plant has evolved over millions of years to prosper in your climate, including temperatures, rainfall and soil. There is no way to explain to a plant that it should bloom in October or November, which is why you are probably not seeing any blooming shrubs around right now. 

There are other possibilities for Fall color and interest that do not involve flowers. The sumac is a shrub that has good Fall color and the female plants have berries that persist through Winter. Follow these links to find out what these four native to Michigan sumacs would have to offer in color and interest in your garden:

Rhus aromatica (fragrant sumac)

Rhus copallinum (winged sumac)

Rhus glabra (smooth sumac)

Rhus typhina (staghorn sumac)

From our Native Plant Image Gallery:

Diervilla lonicera

Cephalanthus occidentalis

Dasiphora fruticosa ssp. floribunda

Spiraea alba

Rhus aromatica

Rhus copallinum

Rhus glabra

Rhus typhina