6 Perennials for Spectacular Fall Color

Standard
20170911a-rachel-kramer-flickr

Cushion mums are as spectacular in bloom as any summer perennial. Photo: Rachel Kramer, flickr

You thought the gardening season was over by September and all you had to do was hang up your gardening tools? Think again! Thanks to climate change, in most regions autumns are longer and warmer than ever and that has extended the flowering season well into November, often even December.

Bulbs (colchicums and autumn crocuses), shrubs (several hydrangeas, seven-son flower [Heptacodium] and common witch-hazel) and many annuals (pansies, snapdragons, hybrid sweet alyssums, etc.) will continue to bloom right through the fall, even sailing through the first light frosts. They won’t stop until a truly hard frost hits. In fact, some annuals, like ornamental cabbage, don’t even start to show color until September. But there are more fall-flowering varieties among perennials than in any other group.

Here are six of the best!

Garden Mums

20170911B jill111, pixabay.jpg

Hundreds of years of hybridizing have led to the popular “cushion mum,” with a dense, dome-shaped habit and hundreds of flowers. Photo: pixabay

There are currently about 20 species of Chrysanthemum, commonly called chrysanthemums or just mums, and all are fall bloomers. However, just because they are sold locally doesn’t mean they are hardy in your region.

Many merchants make little difference between florist chrysanthemums (frost-tender varieties) and garden mums (hardy varieties) and sell pots of both in the fall. The two, after all, belong to the same species (Chrysanthemum × morifolium, formerly C. × grandiflorum and Dendrathema × grandiflorum), a complex hybrid with both hardy and subtropical species in its background. Florist and garden mums may therefore appear to be identical, but florist varieties are often only hardy to zone 8 whereas hardy garden mums are solid in gardens as cold as zone 3. That’s a huge difference!

So, how can you tell the two apart in a store display?

In box stores, supermarkets or other non-specialist venues, you can’t. Chances are all the mums they sell are florist varieties, shipped in from the South in full bloom for rapid fall sales. They’re essentially annuals in most gardens. However, garden centers and plant nurseries  usually offer both garden and florist types. To find out which is which, ask about guarantees. Truly perennial mums will have a 12-month guarantee; tender florist mums won’t.

20170911C Mammoth Red Daisy Ball Horticultural Company

Hardy chrysanthemum Mammoth Red Daisy is a big one, as large as many shrubs! Photo: Ball Horticultural Company

There are some very good garden mums (i.e. hardy cushion mums) out there, varieties known for their resistance to extreme cold, and this includes the Morden, Minn, Firecracker and Mammoth™ series (the latter was formerly known as the My Favorite™ series and that name may still be used by some nurseries). The four series offer single and/or double varieties in a wide range of colors: yellow, orange, pink, purple, white, etc. The Morden and Minn mums are dwarf plants (12-18 inches x 18-24 inches/30-45 cm x 45-60 cm) covered with flowers from September to frost, while the Mammoth series mums are taller and wide: 3 to 4 feet (100-120 cm) tall and wide. Firecracker series mums (Power Surge®, Showbiz®, Suncatcher®, etc.) are of intermediate size.

All varieties mentioned are hardy to zone 3. Sun or partial shade.

Heirloom Mums

SONY DSC

The most popular heirloom mum is ‘Clara Curtis’. Photo: rosekennedygreenway.org

There are also heirloom mums, also called old-fashioned mums or rubellum mums. They’re a different species: Chrysanthemum × rubellum, formerly C. zawadskii latilobum.

This group includes the well-known ‘Clara Curtis’ (pink, zone 3), ‘Duchess of Edinburgh’ (dark pink, area 4) and ‘Mary Stoker’ (yellow, zone 3), plus half a dozen others. All produce simple daisylike flowers with a yellow center. They reach about 18 to 30 inches (45-75 cm) in height and diameter, depending on the cultivar, but have more finely cut leaves than garden mums and certainly don’t form the dense mounds typical of cushion mums. Instead they have a much more open habit and are even inclined to wander a bit. They’re not really invasive, though, as it’s easy to pull out stragglers if they go too far.

Zone 3. Sun or partial shade.

You can read more about hardy mums here: Chrysanthemums for Cold Climates.

Asters

20170911J Patricia-Ballard dorsetperennials.co.uk.jpg

New York aster ‘Patricia Ballard’. Photo: dorsetperennials.co.uk

North American fields and forests are full of wild asters in shades of violet and white, but there also are many cultivated asters to be discovered, including New England asters (Aster novae-angliae, now Symphotrichum novae-angliae) and New York asters (A. novi-belgii, now S. novi-belgii). They have larger flowers in a much wider color range than wild asters. They come in shades of violet (so-called blue), purple, pink, red, and white, often with semi-double or double flowers.

Until recently, most asters were tall to medium-height plants for the back or the middle of the garden. A. n-a. ‘Harrington’s Pink’ (pink, 48 inches x 24 inches/120 cm x 60 cm) and A. n-b. ‘Patricia Ballard’ (dark pink, 36 inches x 15 to 20 inches/90 cm x 40-50 cm) are examples of these popular taller varieties.

20170911E Footprints Plants, LLC.jpg

Aster ‘Purple Dome’. Photo: Footprints Plants, LLC

Dwarf asters, although often sold under the botanical name A. dumosus (a name that really belongs to a summer-flowering Eurasian species), are actually just smaller selections of A. novae-angliae and A. novi-belgii. A. n-a. ‘Purple Dome’, for example, is popular, forming a rounded dome 16 to 20 inches (40-50 cm) in height and width with purple flowers. The Wood’s series of dwarf asters is similar, but comes in other colors.

Fall asters are hardy to zone 4, sometimes in zone 3. Sun or partial shade.

Goldenrod

20170911F F. D. Richards, flickr

Solidago rugosa ‘Fireworks’. Photo: F. D. Richards, flickr

There is a surprising dichotomy between the attitude of North American and European gardeners towards goldenrod (Solidago spp.). North Americans tend to see goldenrods, which are native to their continent, as weeds and want little to do with them. Europeans, on the other hand, for whom they are exotic plants coming from the New World, adore them!

I find it almost criminal to malign these gorgeous perennials with their rich yellow flowers simply because they’re natives when, in fact, they are among the best fall perennials. True enough, Canada goldenrod (Solidago canadensis) is highly invasive species in gardens, both through seeds and wandering rhizomes, but the others are clump-forming and stay put. If you don’t believe me, try S. × ‘Crown of Rays’ (23-27 inches x 18-23 inches/60-70 cm x 45-60 cm), S. × ‘Dansolitlem’ Little Lemon® (12-18 inches x 12-23 inches/30-45 cm x 30-45 cm) or S. rugosa ‘Fireworks’ (36-48 inches x 36 inches/90 to 120 cm x 90 cm), all with stunning feathery yellow flowers. Beautiful!

Zone 3. Sun or partial shade.

Autumn Sedum

20170911G Sedum Herbstfreude HC

Sedum ‘Herbsfreude’. Photo: laidbackgardener.blog

Autumn sedum, also called autumn stonecrop, showy sedum or showy stonecrop (cultivars and hybrids of Sedum spectabile [Hylotelephium spectabile] and related species), is a fairly low-growing plant (rarely more than 2 feet/60 cm tall), with succulent stems and leaves, often bluish green. The star-shaped flowers are produced in dense masses, a bit like colored cauliflower, and come in shades of pink, red or white, more rarely, pale yellow. They’re one of the last fall feeding stations for butterflies.

S. ‘Herbsfreude’ (‘Autumn Joy’), 12-24 inches x 18-24 inches (60 cm x 45-60 cm), is best known and bears pink flowers turning brownish red. S. ‘Autumn Fire’ is similar, but more compact (20 inches x 18-24 inches/50 cm x 45-60 cm). A sturdier plant, it doesn’t tend to flop under the weight of its flowers the way ‘Herbstfreude’ may do. S. ‘Purple Emperor’ (16 inches x 18-24 inches/40 cm x 45-60 cm) is just one of many autumn sedums with dark purple leaves and pink flowers, while ‘Elsie’s Gold’ (16-18 inches x 20-24 inches/40-45 cm x 50-60 cm) has green leaves with yellow to cream edges and magenta flowers. It’s less likely to flop than most other variegated autumn sedums.

There are dozens of other excellent varieties.

Zone 3. Sun.

Turtleheads

20170911H Chelone lyonii Hot Lips HC JPG.jpg
Chelone lyonii ‘Hot Lips’. Photo: laidbackgardener.blog

Turtleheads get their curious name from their flowers, said to look like a turtle’s head. In fact, their botanical name, Chelone, comes from the Greek and also means turtle.

Red turtlehead (Chelone obliqua) is probably the most common variety. It produces a dense, non-invasive clump of solid, perfectly erect stems 24-36 inches tall on a plant 24 inches in diameter (60-90 cm x 60 cm). The very dark green leaves are attractive all summer, but the beautiful deep pink flowers dominate in the fall.

Lyon’s turtlehead (C. lyonii) is very similar in all respects: you can scarcely tell it apart from pink turtlehead (C. obliqua). C. lyonii ‘Hot Lips’ (60-90 cm x 60 cm) is very popular with darker leaves than the species. C. lyonii ‘Tiny Tortuga’ is a dwarf variety only 12-15 inches tall and 8-10 inches in diameter (30-40 cm x 20-25 cm).

Zone 3. Sun or shade.

Maiden Grass

20170911I Miscanthus_sinensis Purpurea HC

Miscanthus ‘Purpurascens’. Photo: laidbackgardener.blog

This tall grass (Miscanthus sinensis) is very popular, grown for its arching green ribbon-shaped leaves that become straw-colored in fall and its blooms that start pinkish to become silver-white as fall progresses. Both leaves and flowers hold on right through the winter into spring, offering six months or more of interest.

In zone 7 and above, maiden grass can self-sow and become invasive due to overseeding, so look for near-sterile varieties like ‘Autumn Light’ and ‘Morning Light’ as well as any of the variegated cultivars, as they almost never bloom.

Seeds don’t mature in cold climates, so maiden grass isn’t invasive there … but it might not perform well there either. Its hardiness varies from zone 4 to 6, so make sure you choose one cold resistant enough for your conditions. Also, some cultivars won’t have time to bloom in short-season climates or will only bloom occasionally in years where the summer was extra-long. Unless your local merchant is a specialist in ornamental grasses, you won’t be warned about this fact, so research your plants ahead of time.

Best choices for bloom in colder climates include the extra=hardy Huron series, including M. s. ‘Huron Sunrise’ (6 feet x 2-3 feet/180 cm x 60-90 cm), zone 3, the popular tall cultivar M. s. ‘Silberfeder’ (7-8 feet x 4 feet/200-250 cm x 120 cm), zone 4, and purple maiden grass (M. ‘Purpurascens’), 5 feet x 2 ½ to 3 feet (150 cm x 75-90 cm), also zone 4. The latter offers distinctly coppery foliage color in fall.

Sun or partial shade.

Even More Fall-bloomers

20170911K autumnasters.co.uk.jpg

Add the right fall-bloomers and your autumn garden will come alive!: Photo: autumnasters.co.uk

There are still many other perennials that bloom in fall: boltonia (Boltonia), Japanese anemone (Anemone × hybrida), helenium or sneezeweed (Helenium), bugbane (formerly Cimicifuga, now Actaea), ironweeds (Vernonia), tall coreopsis (Coreopsis tripteris), Joe-pye weeds (Eupatorium), perennial sunflowers (Helianthus ‘Lemon Queen’ and others), black-eyed susans (Rudbeckia), monkshoods (Aconitum), echinaceas (Echinacea), and many more.

As you can see, with the right choice of plants, there is no reason why your garden can’t be as spectacular in October as it was in July!20170911a-rachel-kramer-flickr

Advertisements

Chrysanthemums for Cold Climates

Standard

In moderate climates, that is hardiness zones 6 to 9, the most popular fall flower is the garden chrysanthemum, often called cushion mum, fall mum, or garden mum. In colder climates, though, chrysanthemums haven’t shown themselves to be particularly hardy and many gardeners have learned to avoid them. Fortunately there are now extra garden mums to try, ones well adapted to climates as cold as zone 3. How did this change come about? Read on!

Classic Garden Mums

The garden mum now goes under its old name, Chrysanthemum x morifolium, after having spent a number of years under the name Dendranthema grandiflorum. It is believed to have first been hybridized in China over 1500 years ago and there are literally thousands of cultivars.

The main botanical chrysanthemum behind the hybrid is C. indicum, a not very hardy species (zones 7 to 12) from India and China. However, many other species have been used, some of them very hardy (zone 3 or even 2), with the result being that some garden mums are very tender and others very hardy. But until recently, you couldn’t tell which, among the dozens of beautiful specimens sold in the fall in garden centers, were going to act like annuals and die over the winter and which would come back year after year.

That’s changing now, as hybridizers in colder climates, mostly Minnesota and Manitoba, have been working on developing cold-hardy cultivars that will readily overwinter in gardens as cold as zone 3. Here are some examples:

Morden Series (C. x morifolium)

2, Chrysanthemum Morden_Fiesta_June_20_1999_large

Chrysanthemum x morifolium ‘Fiesta’

Developed at the Morden Research Station in Manitoba several decades ago, this series provides compact, densely flowering plants with double flowers, very much the typical cushion mum, only much hardier. They also bloom very early (important in short-season areas), starting in late August, and continue for 8 weeks and more. They’re all about the same size (1-1 ½ ft x 1 ½-2 ft/30-45 cm x 45-60 cm) and are hardy to zone 3.

The following varieties are the most popular: ‘Morden Cameo’ (creamy white), ‘Morden Canary’ (yellow), ‘Morden Delight’ (orange-red), ‘Morden Fiesta’ (violet-purple) and ‘Morden Garnet’ (dark red).

Firecracker Series (C. x morifolium)

This is another series developed in Manitoba, this time by Jeffries Nurseries, by crossing less-hardy hybrid mums with those of the Morden series. They start blooming in early September and continue for 8 weeks or so. They vary in size and form, but all are hardy to zone 3.

Dreamweaver® (‘Jefdream’) has semi-double purple flowers with a yellow center. The outermost petals are trumpet-shaped, giving the flower a very original appearance. 2 ft x 2 ft (60 cm x 60 cm).

Firestorm® (‘Jefstorm’) produces semi-double dark red flowers. 1 ft 10 in. x 1 ½-2 ft (55 cm x 45-60 cm).

3. Power_Surge-flowers2

Chrysanthemum x morifolium ‘Power Surge’

Power Surge® (‘Jefsurge’) has fully red double flowers. It’s a compact plant forming a wide dome. 1 ½ ft x 3 ft 4 inches (45 cm x 100 cm).

Showbiz® (‘Jefbiz’) produces an abundance of double purplish pink flowers. 1 ½ ft x 2 ft 6 in (45 cm x 75 cm).

Stardust® (‘Jefdust’) has double to semi-double flowers that are described as “dusty mauve”, but to me open a more bronzy orange melding into a deep pink. 20 in x 3 ft (50 cm x 90 cm).

Suncatcher® (‘Jefsun’): bright yellow double flowers. 2 ft 6 in x 4 ft (75 cm x 120 cm).

Tigertail® (‘Jeftail’): double orange flowers that become yellow over time. 2 ft 4 in x 3 ft (70 cm x 90 cm).

Mammoth™ Series

Developed in Minnesota, these plants result from crosses between C. x morifolium hybrids and the very hardy C. weyrichii. This results in tall, almost shrubby plants with single to semi-double flowers, interesting for the middle or even the back of the flowerbed. Do note though that these plants grow slowly, only gaining their final dimensions of about 4 ft x 5 ft (110 cm x 150 cm) in their third year. This series includes the full range of chrysanthemum colors.

The Mammoth™ series was originally launched under the name My Favorite and you may still see some of these plants sold under their former name.

4. Mammoth red

Chrysanthemum x morifolium Mammoth™ ‘Red Daisy’

Mammoth™ ‘Red Daisy’ (formerly My Favorite™ ‘Autumn Red’.): Semi-double red with a yellow center.

Mammoth™ Coral Daisy ‘(formerly My Favorite’ Coral ‘.): Single coral pink.

Mammoth™ ‘White Daisy’ (formerly My Favorite™ ‘White’.): Semi-double white.

Mammoth™ ‘Dark Bronze’ (formerly My Favorite ‘Dark Bronze Daisy’.): Semi-double orange.

5. Yellow Quill

Chrysanthemum x morifolium Mammoth™ ‘Yellow Quill’

Mammoth™ ‘Dark Pink Daisy’ (formerly ‘My Favorite™’ Dark Pink ‘.): Single deep pink.

Mammoth™ ‘Lavender Daisy’: Semi-double lavender pink.

Mammoth™ ‘Purple’: Single purple.

Mammoth™ ‘Yellow Quill’: Single pale yellow flowers, with the same dimensions as the other Mammoths, but unusual quill-shaped ray flowers.

Igloo Series

Despite a name that seems to suggest excellent hardiness, the Igloo series is less hardy than the others mentioned so far, to about USDA zone 5, AgCan zone 6, although they may be worth a try in a protected spot. Their double flowers come in the full range of colors and they form the typical dome one expects from a cushion mum. Dimensions: about 2 ft x 2 ft (60 cm x 60 cm).

Other Hardy Garden Mums

The following hardy C. x morifolium cultivars do not belong to any series.

‘Prairie Lavender’ is compact with lavender pink flowers. The flowers are double, yet you can still see a bit of the yellow center. 2 ft x 2 ft (60 cm x 60 cm). Very hardy (zone 3).

6. Matchsticks

Chrysanthemum x morifolium ‘Matchstick’

‘Matchsticks’ is less hardy than most other “hardy” mums (USDA zone 4b, AgCan zone 5b), but may be well worth trying because of its very unusual flowers: the rayflowers are yellow-orange and tubular at the base, opening into broader red tips, creating a beautiful contrast. 1 ½-2 ft x 2 ft (45-60 cm x 45-60 cm).

Other Hardy Chrysanthemums

The genus Chrysanthemum was split apart many decades ago into other genera, including Glebionis (annual species), Leucanthemum (typical white daisies), Tanacetum (painted daisies) and others. Among the various chrysanthemum offshoots, the following plants are fall-blooming and still considered “mums” by gardeners everywhere.

7. weyrichii

Chrysanthemum weyrichii

Weyrich Chrysanthemum (C. weyrichii): this is a dwarf species from the very cold Kamchatka Peninsula. It’s a spreading groundcover with low-growing incised leaves that burst into bloom late in the fall, often November. The daisylike flowers can be white (‘White Bomb’ is the usual cultivar) or pink (‘Pink Bomb’). The whole plant is rarely more than 6 to 8 in (15-25 cm) high, but can form carpets 2 or 3 feet (60-90 cm) wide or larger.

Arctic Chrysanthemum (Arctanthemum arcticum, syn. C. arcticum): This one is much like the plant above. The species has white flowers, but the most commonly grown cultivar, ‘Red Chimo’, has pink flowers. The arctic mum reaches only 6 to 12 inches (15-30 cm) in height, but forms a compact mat about 12 to 18 in (30-45 cm) diameter. It blooms in early September. Zone 3.

8. clara

Chrysanthemum x rubellum ‘Clara Curtis’

Rubellum Mum (C. x rubellum, formerly Dendranthema zawadskii latilobum): As called hardy mum, heritage mum and old-fashioned mum, this has long been the most popular chrysanthemum in cold climates due to its tough-as-nails habit: they don’t call it the hardy mum for nothing! Its background remains mysterious (taxonomists keep changing its botanical name), but that doesn’t stop it from being an easy-to-grow garden mum, well adapted to zones 3 to 8.

It has deeply cut, mid-green leaves, a rather open habit (it is anything but a “cushion mum”) and single daisylike flowers. It’s also a bit of a spreader, thanks to creeping rhizomes, and can be floppy if you grow it in other than full sun.

By far the most popular cultivar is ‘Clara Curtis’, with pink flowers, but you will also find ‘Mary Stoker’ (apricot yellow), ‘Princess Margaret’ (bright pink), ‘Duchess of Edinburgh’ (dark pink) and ‘Sheffield’ (pale pink), notably in mail order catalogs.

Growing Hardy Chrysanthemums

Fall mums are perennials and can be grown just like almost any other perennial, although they do have a few particularities worth mentioning.

Planting: Yes, I know: garden centers are full of blooming chrysanthemums in the fall, but ideally, you should purchase and plant garden chrysanthemums in the spring. This will give them to the time to root well before flowering.

If you do buy a plant in the fall in full bloom and plant it as is, it will tend put its energy in producing flowers rather than establishing a strong root system. As a result, even hardy chrysanthemums may fail to survive their first winter. Often you’ll find it lying on its side in early spring, root ball fully exposed, shoved out of the ground by frost heave.

So… if you can’t resist buying a garden mum in full bloom in the fall, you have to be ruthless once you get it home and cut off all its beautiful flowers and buds. This will stimulate the plant to produce new roots once you get it into the ground and thus massively increase its chances of survival. Even so, for the first year, you should cover the plant with a good mulch of shredded leaves once the ground is frozen.

Exposure: Mums prefer full sun and become a bit thin even in light shade.

Soil: Any garden soil is acceptable, but they prefer a rich, well-drained, slightly acid soil.

Fertilization: Add compost or all-purpose fertilizer regularly: chrysanthemums are rather heavy feeders!

Watering: Chrysanthemum have shallow root systems and won’t tolerate prolonged drought. From spring right until fall freeze-up, water thoroughly whenever the soil is dry to the touch.

Multiplication: Divide in spring or take cuttings in early summer. Their seeds germinate readily, but are not true to type.

Staking: Most hardy garden mums (C. x morifolium) have fairly strong stems and won’t need staking. This is in contrast to the large-flowered exhibition types usually grown in greenhouses where each stem needs to be individually staked. Hardy mums (C. x rubellum) may need staking in partial shade.

Pruning: It used to be said that garden chrsyanthemums needed to be cut back by half at the end of June to produce more compact, mounded plants with stronger stems, but the varieties recommended here have strong stems and and a naturally dense habit, so no summer pruning is required. However you can prune back dead stems in spring by cutting them at the base. Do not cut back chrysanthemums in the fall! They need their stems to protect them from the cold of winter. People who prune their mums in the fall tend to lose them.

Insects and Diseases: In general, chrysanthemum are not unduly prone to diseases and insects, but you should avoid moistening the foliage when you water to prevent foliar diseases. Chrysanthemum leafminers can trace sinuous trails in the foliage, but are not particularly harmful to the plant’s overall health. If they bother you, simply remove the infested leaves.

Winter Protection: For hardy varieties, leave the stalks still standing all winter so they can catch dead leaves and snow, thus providing their own winter protection. Mums planted in the fall will however benefit from a thick protective mulch of chopped leaves for their first winter.

Rejuvenation: Mums are reputedly short-lived plants, requiring frequent rejuvenation by division. While this may be true of some of the older varieties of garden mums (C. x morifolium), it doesn’t seem to apply to the hardier types. Certainly the hardy species (C. weyrichiiC. x rubellumA. arcticum, etc.) seem to live on and on. And I have clumps of some the Mammoths that are over 10 years old. If you’re worried about this, don’t hesitate to divide them every 2 or 3 years, ideally in the spring.

Where to Find Hardy Mums?

Oddly, local garden centers in cold regions often sell mostly zone 7 or 8 mums in the fall, although you may find some hardy ones tucked away in the perennial section. You’ll probably find a better choice of truly hardy mums (print out the list above and bring it with you) in the spring. Certainly hardy mums are much easier to find today than 10 years ago

Many mail-order nurseries also offer a good choice of hardy fall mums.

So, hardy garden mums do exist. It’s up to you now to find and to plant them!