Jennifer Schultz Nelson
Extension Educator, Horticulture
Fall gardening seems to be attracting more and more attention each year. Most of us associate planting flowers with spring. But choosing to plant fall flowers does open up a whole new world of gardening if you haven't tried it before.
Growing up, my mom always planted annuals each spring, and they lasted until the first frost. As I got more and more interested in gardening, I wanted to try different things, including fall flowers. My mom was not interested. She said she didn't want me to waste my money like that, since the flowers would be killed by frost all too soon. To avoid an argument, I didn't bring home any fall flowers.
I waited until I had an apartment of my own to waste my money without my mom around to object. And it turned out that fall flowers weren't a waste of money. Even my mom reluctantly agreed with me, while she looked at the pansies still in full bloom on my balcony in November.
The first fall flowers I grew are still my personal favorites-- pansies and violas. Pansies and violas are both from the genus Viola. They have a similar face-like appearance, but pansies have been selected to produce bigger flowers than violas. Violas produce dozens of smaller flowers on one plant. Both are extremely cold-hardy, surviving light frosts with ease.
Chrysanthemums are another popular fall flower-- a very cold-tolerant flower, but don't count on it to survive the winter. People often ask me which mums will overwinter well. Unfortunately, there is no way to know by looking at them. Even the ones labeled "perennial chrysanthemum" may behave like an annual and not survive to see next spring.
The best advice I can offer on overwintering mums is to choose a sheltered, well-drained location, plant them early so their roots will establish well before winter settles in, and add a little extra mulch around them for the winter.
I do not remove any of the dead foliage after my mums are done blooming for the year. The dead stems help hold the mulch in place, and offer a little protection of their own. I remove the dead stems in the spring only after I see new shoots emerging. So far, I've lost only a couple of the mums I planted six years ago.
It's tempting to think that bigger (and more expensive) is better when planting mums. This is not always true. Most of my mums, which are huge now, started out in little three inch pots and only cost about a dollar. I've received really large mums as gifts in eight inch or greater pots that barely made it through one season let alone survived the winter.
It takes a lot of energy for a large mum planted in the fall to grow enough roots to survive the winter. In contrast, a smaller plant has a smaller root system to contend with. The lower temperatures and sunlight of fall also means there is less energy for the plant to work with-- so again the smaller plant wins out.
Another favorite cool season flower with a little better chance of overwintering successfully is the aster. Not all asters are perennial, but those that are can get quite large.
A star in my fall garden is Aster oblongifolius 'Raydon's Favorite'. This aster is native to states that are part of the Mississippi River watershed. This plant took a little while to establish in my garden, but this year it is HUGE, about three feet tall and four feet wide. It starts flowering in September, and remains covered in tiny blue-purple flowers through frost.
Asters prefer well-drained soil in full sun. Once established, they will tolerate drought to some degree. They will also tolerate clay soil to some extent. They are susceptible to several fungal diseases if there is too much moisture present, including root rots.
A newcomer to my fall garden this year is flowering kale. I have seen these plants in years past, and have been meaning to give them a try. Finally this year I followed through! I have planted one called 'Peacock Red' which has an attractive lacy leaf with a red center vein, arranged in a rosette. New leaves in the center of the rosette have a deeper shade of red. I also grew a white variety, 'Chidori White' which has broad leaves, much like a cabbage, but with a striking white vein and the center leaves are pure white. They should keep up their show well into fall and even early winter. Plus, they are edible, just like other varieties of kale- but more colorful.
I tend to stick to fall flowers that have some chance of re-seeding or surviving into at least the early winter, to get the most bang for my buck. In the case of pansies and violas, I can get a good three months of flowers in the fall, plus a two or three months of bloom in the spring-- that's five to six months of flowering, easily equaling or exceeding all my 'summer' annuals. To me that is proof that fall flowers are not a waste of money-- chosen wisely they are a great way to stretch your gardening dollars. Given the state of our current economy, I don't foresee myself changing my ways anytime soon.