If ever a season could be called bittersweet, fall is that season. Not the scientific fall, which occurs this year on Sept. 22, but just before then, when the nights come noticeably earlier and are definitely cooler. Mosquitoes are on the wane, humidity is down (now referred to as “damp.”), and it’s much more pleasant to work in the garden.

If your garden lacks the charm it had in July, it’s time to rethink your choices. Plants that carry the garden through until frost and even beyond should be introduced. While it’s best to plant most of them in spring, now is the time to clear out the garden to make room for them.

There are dozens of plants that will pick up the color pace in September. Here are six to start with.

Mum Was the Word

Chrysanthemums are now in the genus Dendranthema, but for purposes of this feature, we’ll refer to them as mums. I’ve grown several, and I always plant them in the spring. This year I’m growing two varieties in the Igloo series. They’re both new on the market and were sent to me by Rozanne and Friends to test in my garden. I pinched them back just once, removing about an inch or so from each stem around July 1. This series of mums is bred to be compact, and are described as needing no pinching. Because I don’t have the six hours plus of full sun that mums prefer, they tend to grow taller than shown on the tag, stretching toward the sun. They now are no more than around 18 inches tall and smothered in buds just waiting to pop. In their first year after spring planting, mums in the Igloo series (like ‘Harvest Igloo’) bloom later in the season than they will in subsequent years.

Asters

Asters also have had a name change, and it’s a doozy. Symphyotrichum is the botanical moniker for the flower that is often in the blue range as far as color goes. It’s a diverse group, from rangy and shade-loving to perky, stiff-stemmed sun worshippers. I’ve grown a variety of hybrids that run the gamut in size and even color. For small gardens and gardeners who prefer a low growing mound, ‘Wood’s Light Blue’ is amazing. Growing no more than 20 inches tall and smothered in bloom, this hybrid also is available in blue, purple and pink. The name “Wood’s” refers to the hybridizer, an apple grower in Portland, Oregon named Ed Wood.

One of the problems with some of the taller asters is that, by the end of summer, the leaves on the lower part of the plant die, leaving ugly bare stems. The plant goes on to bloom just fine at the uppermost stems. The best way to prevent or at least mitigate the damage is to avoid overhead watering, divide the plant every three years, and make sure it is watered about an inch a week during droughts.

The Chicago Botanic Garden’s plant evaluation manager, Richard G. Hawke, published an extensive evaluation report on cultivated asters that lists dozens of different varieties, rating them for bloom coverage and disease resistance.

Dahlias

Whether you plant them as tubers (a swollen root like a potato) or buy them as potted plants, Dahlias will wow you from August through frost. If you have at least six hours of direct sun each day, it’s certainly worth it to try these outstanding flowers. When you have Dahlias growing—especially those that are taller than three feet—the rest of your garden fades into the background.

For the best choice, order tubers from specialty nurseries. Several online retailers sell dahlia tubers in the very early spring in bags containing three tubers for around $10 to $15. It’s best to order them online as early as December to assure you will get what you want the following March or April. Longfield Gardens opens their online shop in December. They offer a great video How to Plant Dahlias.

Specialty growers like Swan Island Dahlias offers single tubers that range in price from $6 to $35. But Dahlias are all they do, so they know their stuff. There are other retailers that specialize in bulbs of all kinds, also good sources for Dahlia tubers. Two are Old House Gardens and Brent and Becky’s Bulbs.

More and more garden centers are offering Dahlias in pots. The shorter the variety, the easier they are to transplant into your garden. They also are good in containers.

Salvia: A Hummingbird’s Last Buffet

If you’ve enjoyed hummingbirds in your garden throughout the summer, there is no better farewell party plant than Salvia. In the sage family, decorative Salvia comes in a wide array of sizes, forms and colors.

Four varieties that have stood out as hummingbird magnets are tall and loosely-formed. Some have even required staking. They are:

1. ‘Amistad’: one of the best Salvias for large blooms in a deep shade of blue. In my partly sunny garden, I’ve used stakes to keep it from laying all over its neighbors. It grows around four feet tall and at least five feet across by the end of summer.
2. ‘Wendy’s Wish’ and ‘Love and Wishes’: I’ve grown both of these Australian-bred beauties, and have been amazed at their bloom power. Like most of the Salvias, they don’t do much until it gets hot. Then you can’t stop these brawny 4’ by 5’ stunners from blooming. They don’t hold back when the nights cool down; in fact, they increase bloom production as if they know it’s their last chance before a heavy frost takes them down. The sales of both plants benefit Australia’s Make-a-Wish Foundation.
3. Burgundy Scarlet Sage (Salvia splendens ‘van Houttei’) can be grown in partial to full shade, and like the others, really puts on a show from late summer through frost. For me it grew up to nearly four feet tall, and the hummingbirds loved its huge burgundy and scarlet flowers.
4. Salvia ‘Playin’ the Blues’: A newcomer in the world of Salvias, ‘Playin’ the Blues’ was one of the sample plants I received this spring from Proven Winners. From mid-July, each spike has remained colorful even after the individual flower dries up, providing some of the most long-lasting color in my garden. As its name indicates, flowers are blue, and the plant, for me, has reached just around three feet tall. It’s in a container by the window so I can see the hummingbirds fight over its nectar.

Goldenrod: It Doesn’t Make You Sneeze

Goldenrod (Solidago) has gotten a bad rap. It’s been thrown into the same bin with ragweed, a rampant plant that keeps a much lower profile. I wonder if part of the confusion stems from ragweed’s botanical name, which is Ambrosia, the same term used to mean “food of the gods.” Go figure. A more likely cause for its reputation as a major sneeze-inducer is that it’s the most visible candidate during the same time ragweed is spewing its pollen. Both plants are native to North America, and therefore can be found in just about any field come September. Guess which one is more visible, and therefore, gets fingered for respiratory unrest.

I love Solidago for its prowess as a cut flower, its gracefully bright presence in an otherwise colorless scheme, and its easy-care nature. The variety I’ve enjoyed the most is called ‘Fireworks’, an upright grower with stems that curve downward for a fireworks look. The only warning I’d offer for planting goldenrod in your garden is that it spreads quickly.

Marigolds? Really?

It’s amazing what you will find in all of those catalogs that come around Christmas. The ones that offer seeds, bulbs, perennials, and all sorts of unusual plants. I was intrigued by a Marigold I’d never heard of called ‘Cinnabar’ (more correctly Tagetes erecta ‘Cinnabar’). Its common name is Cinnabar African Marigold, but it’s no big-headed, look-at-me lollipop flower. It won’t get lost in the garden, though. That’s because its stems grow two to three feet tall.

‘Cinnabar’ is one of those plants they call “see-through,” its stems thinly-clothed in finely dissected foliage that allows a plant behind it to show through. Its flowers, about the size of a quarter, are a spicy deep red with a gold center, and seem to float in the air. It looks especially good with Salvia, Solidago, and any of the mums and asters. And it’s just as easy as any marigold to start from seed.

Asters (Michaelmas Daisy)

These long-lived perennials are perfect for middle of the border displays and dependable fall color. Asters have daisy-like flowers that bloom in shades of blue, lavender and purple that combine well with the rich colors of fall. Grow asters in a sunny spot with evenly moist soil. The variety Aster ‘Alert’ has vibrant carmine purple blooms on plants that are more compact – perfect for fall container gardens.

Tip: Asters are descended from native wild flowers and do not need rich soil or a lot of fertilizer. Avoid wetting the foliage with overhead watering to keep the leaves free of disease. Divide aster clumps every three to four years in the spring or fall replanting only the outer clumps of the mother plant.

Chrysanthemums (Mums)

The traditional flower of the autumn season; mums the word for a variety of color and flower shapes. You can purchase potted mums at the end of summer to replace your summer-weary annuals growing in containers. Once the blooming season is over, transplant the perennial mum plants into the ground where they will be more likely to survive the winter and provide more blooms in the years to come.

Tip: In June prune back the new growth on your mum plants to one half their height. This will ensure that the plants have compact and sturdy stems to support the fall flowers.

Ornamental Cabbage and Kale

Big, bold foliage with ruffled edges make these plants show stoppers in container gardens and garden beds. Cabbage and kale will do best in partly shaded areas and cool climates. If you live in a hot summer climate unless you wait until October and plant once the cooler autumn weather arrives. The colorful heads of ruffled leaves look best when viewed from above or when displayed on a hillside or slope. Combine the rounded shape of these foliage plants with upright bloomers like mums and asters for outstanding fall color displays.

Tip: Protect cabbage and kale from slugs and snails to avoid the look of lacey leaves.

Winter Pansies

Fall will really resemble a second spring if you add the cold-tolerant pansy varieties to your garden. A cool spot with moist soil is best for pansies and violas and summer container gardens that need a fall facelift can be revitalized by adding some winter pansies to the mix. Winter pansies will often survive mild winters to flower again in early spring. Landscapers that add a fall planting of tulips or daffodils will plant a display of winter pansies on top of the bulb installation for instant fall color and as a spring backdrop for the blooming bulbs.

Tip: Deadhead or remove the faded pansy blooms to keep these plants in almost continuous bloom.

Sedum ‘Autumn Joy’

There are many sedums that bloom late in the season, but sedum ‘Autumn Joy’ provides the largest panicles of blooms with a long season of color. In mid-summer the flat flower buds are lime green, changing to cream, then peach and finally rust as winter arrives. This is a great perennial for attracting more pollinating insects to the garden and sedums are naturally drought resistant.

Tip: To make this perennial more compact with sturdy stems, shorten the new growth by one half in late May. This forces more branching, more flowers and autumn joy.

Echinacea (Coneflower)

This North American native plant will survive drought and average soil and still pump out the daisy-like blooms all summer and into the fall. Butterflies and birds are attracted to the center seed pods and plenty of new varieties offer brighter colors and longer lasting blooms. Look for vivid orange, yellow, pink and cream shades.

Tip: This perennial is great for cut flowers and by harvesting the blooms you’ll be encouraging even more flowers. Divide mature clumps in spring or fall to increase you supply.

Rudbeckia Daisy

A native meadow flower, rudbeckias do well in sunny sites with good drainage where they provide late summer and fall color up until the first hard frost. New varieties provide more colors and different sizes but the gold standard is still the golden rudbeckia called ‘Goldsturm’ with sturdy stems that support the bright yellow blooms without the need for staking.

Tip: This perennial is easy to divide and move about the garden for repeating clumps of color. Dig into the center of the plant with a sharp shovel and separate sections in early spring.

Ornamental Grasses

The tall clumps of ornamental grass that look spectacular in the fall are best planted in the spring, but the shorter varieties such as blue fescue are under one foot tall and can be added to the landscape in the fall for instant texture, color and gratification. A new variety Festuca ‘Beyond Blue’ is especially drought resistant and has a tidy growth habit as well as blades that stay blue all year long.

Tip: The blue fescues do not go dormant or turn brown in the winter and do not need to be pruned back in the spring.

Unusual Fall Blooming Bulbs – Autumn will really look like your second spring if you add these bulbs that flower in the fall. Unlike traditional spring blooming bulbs, these plants send up green leaves in the spring, then the foliage disappears in the summer. Just when you have forgotten all about the buried bulbs the flowers emerge without foliage in the fall to accent the landscape and celebrate the season year after year.

Colchicum

The large white or purple petals of this low growing bulb resemble water lilies and are always a bit of a surprise when they suddenly erupt from the ground in autumn. The blooms have no foliage so they look great surrounded by low growing groundcovers such as sedums or lamiums. Colchicums like well drained soils like most bulbs but they do need summer moisture and in warm summer climates they prefer a shaded site.

Tip: Buy and plant this bulb in early September but don’t delay – get the fresh bulbs into the ground immediately as they are not dormant and can dry out. You will be able to enjoy blooms the very same autumn.

Lycoris

This fall blooming bulb is a member of the lily family and the funnel shaped blooms do well in hot southern climates. Great for areas that suffer from deer and rodent damage as this bulb is not edible. Look for Lycoris radiate also known as the spider lily if you want to add a punch of bright red color and an unusual shape to your autumn garden.

Tip: Be patient and give this fall planted bulb a year or two to settle in before the flowers appear. Once it blooms you’ll have many years of returning color with little care.

Fall Crocus

The legendary saffron crocus or crocus sativus is the golden crocus that chef’s love to grow and can be planted in the spring or fall. You can harvest the yellow pollen to use as a homegrown spice to add a yellow color to rice and an exotic flavor to recipes. Another crocus that blooms in the fall is the species crocus (crocus speciosus) with pale purple blooms. The species crocus is easier to grow and will spread into larger colonies as the years go by.

Tip: Plant fall crocus under shrubs and trees with autumn foliage color. They will add to the delight of a fall pocket garden.