Jonathon Hofley / Michigan Gardener
Clusters of blooms on long stalks add a delicate touch of color.

by George Papadelis

Tall verbena or Verbena bonariensis is one of those plants that no garden should be without. In a sunny location, its lavender purple flowers will sway in the wind atop 3 to 4 foot tall, wiry stems. It will bloom from spring until late fall since its excellent heat tolerance is followed by equally superb frost tolerance. It doesn’t require staking or deadheading and once established, it will rarely (if ever) require watering. And we’ve really only just begun to describe the merits of this terrific plant, which is treated as an annual in areas zone 6 or colder.

The flowers of tall verbena even drop seeds that will germinate the following spring and could be transplanted to create a repeat performance. It reseeds so prolifically that many gardeners treat this species as a “perennial.” I have had an infinite supply of Verbena bonariensis seedlings in between the pavers of my patio for seven years.

In our quest to create perennial gardens that bloom from spring to fall, we are typically burdened with examining the bloom times of countless perennial varieties. One convenient solution is to incorporate annuals with a “perennial look” that will bloom all season. Tall verbena is the perfect choice. And since it is grown from seed, it is usually available in economical flats as opposed to more expensive individual pots. Planting them in clumps of 6 or more gives the best effect. Space plants about 12 inches apart.

In summer annual beds, tall verbena is equally valuable. Annuals growing over three feet tall in shades of bluish purple are rare; only the tall annual aster (‘Matsumoto Blue’) and blue glory bush (Tibouchina) come to mind, and both of these can be hard to find. The small airy flowers of tall verbena are especially effective when contrasted with composite (daisy-type) flowers. Annual black-eyed Susan varieties (Rudbeckia hirta) offer several great choices in shades of yellow, gold, and orange. The electric orange flowers of the dwarf Mexican sunflower (Tithonia ‘Fiesta del Sol’) would also make a perfect companion. Even the red flowers of the common annual geranium (Pelargonium) look fantastic with tall verbena planted behind them.

Eric Hofley / Michigan Gardener
Verbena bonariensis is most dramatic when planted in drifts.

It wouldn’t be fair to not tell you about a Verbena bonariensis relative that I am sure you will also love. Many of you are probably familiar with the creeping or trailing verbenas that are usually hybrids of Verbena canadensis. These are usually grown from cuttings and perform beautifully in pots and beds. But there is another garden worthy species called Verbena rigida or rigid verbena. These also produce purplish-blue flowers, but the plants are only about a foot tall. Cultivars from cuttings have been available, but now there is a seed-grown variety called ‘Santos Purple.’ It has vibrant purple flowers on 10- to 12-inch tall plants. Its vibrant flowers can be seen from low-flying aircraft and my favorite part is that almost nobody can identify it. Even the most plant-savvy gardeners will ask, “What is it?”, “Is it a perennial?”, “Is it an annual?”. If you appreciate plants that are outstanding performers and that may potentially stump onlookers, then you must have Verbena rigida ‘Santos Purple.’

Both of these verbenas may be tricky to locate but they certainly offer traits that make them well worth the hunt. Try them in your garden and you too will soon be saying, “This is one of those plants no garden should be without.”

George Papadelis is the owner of Telly’s Greenhouse in Troy, MI.

At a glance: Tall verbena

Botanical name: Verbena bonariensis (ver-BEE-nuh bo-nar-ee-EN-sis)

Plant type: Treated as an annual (tender perennial; hardy to zone 7)

Plant size: 3-4 feet tall, 3 feet wide

Habit: Wiry and open

Flower color: Lavender purple

Flower size: Clusters 1 to 1–1/2 inches across

Bloom period: Summer to fall

Light: Sun

Soil: Well-drained

Uses: Annual bed, perennial border

Companion plants: Annual black-eyed Susans, tall cosmos, Mexican sunflower, tall dahlias, daylilies, and many more annuals and perennials.

Remarks:  Will reseed readily. Unwanted seedlings are easy to pull out. Although it is tall, can be used in the middle or even front of beds due to its open growth habit. Blooms appear to float in the breeze. Tolerates some frost.

Jonathon Hofley / Michigan Gardener
‘Alba’by George Papadelis

Heliotrope continues to be one of the most sought after annual plants every spring. Some varieties have intoxicating, vanilla-scented flowers that are irresistible, while others have beautiful blue, white, or lavender flowers. Its potent fragrance earned it the common name “cherry pie,” however, I have never heard anyone suggest that the scent even remotely conjures hints of any kind of pie. Heliotrope “flowers” are actually clusters of 1/4-inch blooms that develop in masses to form 4- to 8-inch heads. Among gardeners, the purple-blue varieties are the most desirable for their flowers, which combine so well with shades of pink, silver, or gold.

The rich, velvety flowers have become more and more popular in container gardens. Even the gardeners of the Victorian period recognized its value in potted combinations. Now that the huge, trailing leaves of golden sweet potato vine have made it into the container plant spotlight, heliotrope has been revealed as one of its perfect partners. Deep green heliotrope leaves and rich blue flowers above the golden leaves of sweet potato vine—wow! Add a trailing pink verbena or ivy geranium and you have a truly vibrant display.

Heliotrope is also a wonderful plant for bedding. One of my fondest heliotrope memories is a stunning combination I saw at the beautiful Butchart gardens in British Columbia about 10 years ago. Heliotrope was alternated in a mass planting with the variegated leaf geranium ‘Mrs. Parker.’ The cream and green leaves of the geranium shined beautifully below the bright pink geranium blooms and deep blue heliotrope flowers; it was breathtaking! In this example, even heliotrope’s dark green leaves were used to contrast with other foliage.

Johnny’s Selected Seeds
‘Marine’The most popular heliotrope is a readily available, seed-grown variety called ‘Marine.’ It is only slightly fragrant but has the navy blue flowers for which heliotrope is so commonly praised. It grows 15 to 18 inches tall. Because it is seed grown, it is usually the easiest for growers to produce and therefore the most inexpensive heliotrope to buy.

A cutting-grown variety called ‘Atlantis’ is rapidly becoming more popular. The flowers are about the same as ‘Marine’ but the plant seems to be more resistant to stretching. This makes it more desirable in situations where crowding (and thus stretching) might occur.

EuroAmerican Propagators
‘Azure Skies’The variety ‘Nagano’ is arguably the most fragrant blue heliotrope. The flowers emit a baby-powder scent that is strongest in the evening. It has the more compact growth habit of ‘Atlantis’ but sports deep violet-blue flowers.

In my opinion, the most fragrant variety is the white cultivar called ‘Alba.’ I know very little about aromatherapy, but I can’t imagine life without experiencing nature’s most pleasant scents. To remove a flower and enjoy its fragrance for even a few minutes is well worth the space required to grow this plant. White heliotrope’s vanilla scent is rivaled by few flowers; jasmine and English roses come to mind. This is an attractive plant but it is rarely grown for its beauty alone.

One of the newest varieties is a unique trailing version called ‘Azure Skies.’ Oddly, this one has no fragrance and grows more horizontally rather than upright. Its lavender flowers can be used to trail over the edge of a pot or it may be used for bedding as a low spreading mound about 8 inches tall.

Jonathon Hofley / Michigan Gardener
‘Azure Skies’All heliotrope prefer full or partial sun and all thrive in well-drained soils. Plants grown too cold or too wet can develop root rots. That being said, don’t allow plants to dry out. They are occasionally attacked by aphids but insecticidal soap can solve that problem.

Heliotrope can offer beautiful flowers as well as incredible fragrance. Once you have decided how you are going to use it, all you have to do is choose the appropriate variety. If you have never planted heliotrope and you don’t intend to have it in your garden, hopefully you will encounter it some day and experience its remarkable fragrance.

George Papadelis is the owner of Telly’s Greenhouse in Troy, MI.

At a glance: Heliotrope

Sunny Border Nurseries
Coreopsis ‘Heaven’s Gate’ by George Papadelis

Many gardeners covet long-blooming perennials. Perennials that bloom for more than six weeks are particularly valuable in gardens with limited space. Fewer varieties can be used to provide the garden with color from early spring until late fall. Within a given genus of perennials such as Salvia, Veronica, or Geranium, there may be various varieties with a broad range of flowering periods. Similarly, tickseed or Coreopsis is a genus that contains some of the most popular long-blooming perennial varieties. All Coreopsis attract butterflies and are easy-to-grow plants derived from American native species.

The most popular species is Coreopsis verticillata or thread-leaf coreopsis. This species contains several varieties, all of which have fine, “thread-like” foliage. The variety “Moonbeam” was chosen by the Perennial Plant Association as the Perennial Plant of the Year in 1992. It grows 12 to 18 inches tall, 24 inches wide, and produces a myriad of pale yellow, daisy-like flowers. It begins blooming in early June and will continue to flower for about 10 to 12 weeks. Removing the spent flowers can further prolong flowering. This practice, however, is seldom considered worthwhile due to the profuse flowering of the typical ‘Moonbeam.’

Eric Hofley / Michigan Gardener
The pale yellow flowers of Coreopsis ‘Moonbeam’ echo the leaves of this variegated iris.The variety ‘Crème Brulee’ has much larger and brighter pale yellow flowers than ‘Moonbeam.’ It grows slightly taller at about 18 to 24 inches tall. It has a thread-leaf that is more coarse than ‘Moonbeam,’ so it can be more prone to floppiness. Plant ‘Moonbeam’ and ‘Crème Brulee’ with summer-blooming blue perennials such as veronica and salvia.

Two other thread-leaf coreopsis are relatively easy to find. ‘Golden Showers’ produces golden yellow flowers shaped like those of ‘Moonbeam,’ but is a much more upright grower. It grows about 24 inches tall and 18 inches wide. Flowering begins in June and persists well into fall. The variety ‘Zagreb’ is bushy and shorter, with bright yellow flowers on 12- to 18-inch plants.

Jonathon Hofley / Michigan Gardener
Coreopsis grandiflora ‘Sunray’ The shortest species is Coreopsis auriculata, growing only 6 to 10 inches tall. The variety ‘Nana’ is long-lived and begins to bloom earlier than other coreopsis. Flowering begins in May and continues until July. The single orange-yellow flowers develop over a low carpet of rounded leaves. This one is especially well-suited for use as edging or a rock garden plant.

The tallest species is Coreopsis grandiflora. These produce the largest flowers within the genus. They grow from 1 to 3 feet tall and are some of the longest-blooming perennials available. Flowering usually begins in June and continues until September, especially if spent flowers are removed. The drawback is that they are likely to bloom themselves to death; the Coreopsis grandiflora varieties (except for ‘Flying Saucers’) can put so much energy into fall flower and seed production that the weakened plant may not overwinter. The removal of flower stems and seed pods beginning in early September will encourage the development of a strong crown that is more capable of winter survival.

Jonathon Hofley / Michigan Gardener
Coreopsis ‘Limerock Ruby’ Several varieties of Coreopsis grandiflora exist but these are some of the most noteworthy. ‘Goldfink’ is the shortest Coreopsis grandiflora at only 8 to 10 inches tall. It produces several 1-1/2-inch, single gold flowers. ‘Baby Sun’ (aka ‘Sonnenkind’) is another short variety at 12 to 20 inches tall. It forms a mound of single golden-yellow flowers about 2 inches across. ‘Early Sunrise’ is a former All-America Selections winner and one of the few perennials to receive this distinction. It produces semi-double golden flowers on plants that are 18 to 24 inches tall. ‘Sunburst’ is the tallest Coreopsis grandiflora available at 30 to 36 inches tall. It has larger gold flowers on longer stems and is the best cultivar for cutting.

‘Sterntaler’ offers a unique 2-inch gold flower with a mahogany-brown circle around the center. It grows 16 to 18 inches tall. The variety ‘Tequila Sunrise’ is the only Coreopsis available with interesting green and cream variegated foliage. It produces single gold flowers over plants growing 16 to 18 inches tall. This relatively new cultivar has proven to be somewhat less hardy than others so take precautions such as improving drainage and providing additional winter protection.

Perhaps the most effortless and dependable Coreopsis grandiflora is “Flying Saucers.” This one has sterile flowers that cannot waste energy on seed production. That means it can spend more energy on flower production and gathering strength for overwintering. Golden yellow flowers are produced well into fall and deadheading is far less necessary. Its profuse flowering makes it suitable for use in containers too.

Pink varieties of coreopsis come from the species Coreopsis rosea. The best variety with all pink petals is Coreopsis rosea ‘American Dream.’ Ironically, this plant was the Perennial Plant of the Year in Europe several years ago. It yields several 1-inch, rose-pink daisies with a tiny yellow eye. It grows 8 to 16 inches tall and will bloom until fall if deadheaded. ‘Sweet Dreams’ has large, distinctly bi-colored flowers that combine soft pink petals with a large raspberry pink center. It can grow floppy in more fertile soil, but pruning away the top half will make plants more compact and bushy.

Heritage Perennials
Coreopsis grandiflora ‘Flying Saucers’ A while ago, an exciting new ruby-red coreopsis called ‘Limerock Ruby’ was introduced. Millions were sold all over the world and unfortunately, it became evident that ‘Limerock Ruby’ was not hardy in the colder zones (it is only hardy to about zone 7). Since then, ‘Limerock Ruby’ has tragically become almost impossible to find in most garden centers. It blooms all summer and produces hundreds of flowers. This color is very rare in the flower color palette; only a few plants such as chocolate cosmos and Scabiosa ‘Ace of Spades’ offer blossoms of a similar hue. This plant is certainly worth the effort to track down and perhaps an increase in consumer demand will keep this great annual from disappearing.

Since the demise of ‘Limerock Ruby,’ another selection at least partially fills the void: ‘Heaven’s Gate’ is the deepest pink coreopsis available. It is truly hardy to zone 5 and flowers all summer long.

Coreopsis offers a huge range of different flowers and foliage on plants that display exceptionally long bloom times. In large, English style borders that abound with daisies, lilies, gayfeather, bee balm, and daylilies, coreopsis is a wonderful addition. In smaller gardens, where only a few plants can get squeezed in, high performance perennials like coreopsis are a must.

George Papadelis is the owner of Telly’s Greenhouse in Troy, MI.

At a glance: Coreopsis

Botanical name: Coreopsis (kor-ee-OP-sis)

Common name: Tickseed

Plant type: Perennial

Plant size: 8-36 inches tall, 8-24 inches wide

Habit: Clumping

Hardiness: Zone 4 or 5

Flower color: Pale yellow, golden yellow, pink, deep pink

Flower size: 3/4 to 2-1/2 inches across

Bloom period: Summer to early fall

Light: Sun

Soil: Well-drained

Uses: Perennial border

Companion plants: Blue-flowering perennials like salvia and veronica; daisies, lilies, gayfeather, coneflowers and daylilies.

Remarks: Can be short-lived (a few years). Deadhead spent blooms to prevent seed production, which prolongs the life of the plant.

Jonathon Hofley / Michigan Gardener
Plectranthus argentatusby George Papadelis

Gardeners continue to covet beautiful foliage in every aspect of their landscapes. More than ever, we are likely to look beyond the flowers and learn to appreciate the foliage; flowers come and go, but foliage endures. In perennial gardens, for example, fancy-leaved versions of old favorites are very popular. Trendy perennials like the Jacob’s ladder (Polemonium) ‘Stairway to Heaven,’ phlox ‘Becky Towe,’ and bugbane (Cimicifuga or Actaea) ‘Hillside Black Beauty’ are adorned with much more decorative foliage than their green-leaved relatives. Some popular annuals like coleus and sweet potato vine are used purely for their gorgeous leaves. Plectranthus is also grown primarily for its gorgeous leaves, like its relative coleus. This enormous genus is also blessed with fragrant leaves and a huge range of uses.

Most of the ornamental plectranthus have the unique ability to tolerate either sun or shade. The durable leaves rarely shed and will withstand strong winds. Plectranthus is also very drought tolerant and even quite tolerant of rough handling.

Jonathon Hofley / Michigan Gardener
Plectranthus fosteri ‘Marginatus’The genus is most easily divided into three distinct groups: 1) upright foliage, 2) trailing foliage, and 3) attractive flowers. Among the upright forms, we have the silver-leaved Plectranthus argentatus. Silver foliage is almost always desirable amongst other foliage and flowers. These prefer sun and produce large silver leaves with a felt-like texture and slightly serrated edges. They may grow up to two or three feet tall, making them ideal for larger plantings or containers. Pinching may be necessary to control height and encourage branching. I have seen Plectranthus argentatus used in the center of a large container in combination with the upright blue angelonia, pink trailing petunias, and white trailing Nierembergia—a beautiful and durable combination.

It should be noted that almost every plectranthus is grown from cuttings. That means you will typically pay a bit more for a single plant (compared to seed-produced plants). In 2005, however, there was a breakthrough in plectranthus. Some seed companies began offering a new Plectranthus argentatus grown from seed called ‘Silver Shield.’ It branches better than the one grown from cuttings and the height and spread are about 24 inches. Seed-grown plants are typically a bit more affordable since they are often available in flats.

Jonathon Hofley / Michigan Gardener
Plectranthus fosteri ‘Green on Green’The other upright forms are Plectranthus fosteri ‘Marginatus’ and Plectranthus fosteri ‘Green on Green.’ The former has green and white variegated foliage and the latter has green and gold variegated foliage. The leaves are similar to Plectranthus argentatus, but are sometimes much larger. The thick, scented leaves on upright stems weave beautifully amongst the flowers and leaves of other annuals or perennials. Both of these can be very quickly grown into standards: stake the stalk to the desired height, then repeatedly pinch to create a terminal poodle or globe shape. These prefer sun or part sun.

The trailing varieties will thrive in sun or shade. They can be used for bedding or simply used as a more interesting vinca vine replacement. For trailing silver leaves, try Plectranthus x ‘Silver Foil.’ Plectranthus madagascariensis ‘Variegatus’ has bright green and white variegated leaves that will trail down and continue to maintain a nice mounded habit. It is striking next to bright colors like petunias or with the white flowers of Bacopa.

Jonathon Hofley / Michigan Gardener
Plectranthus oertendahlii ‘Uvongo’One of the most interesting trailing forms is Plectranthus oertendahlii ‘Uvongo.’ It hugs the ground and produces beautiful silver and green patterned leaves. The best part is the showy purple-pink undersides that reveal themselves just enough to give ‘Uvongo’ delicate rose accents. In more sun, the stems turn purple and so does the new growth. Try this one in a container interplanted with euphorbia ‘Diamond Frost’ (tiny upright flowers) and the blue trailing flowers of lobelia ‘Big Blue.’

Another beautiful trailing plectranthus is ‘Troy’s Gold.’ This one is also quite short, only growing to about five inches tall. Leaves are brightly variegated green and gold with some deep purple veins. The stems and leaf undersides on ‘Troy’s Gold’ are also purple. Plant this one with any purple or gold flowers for optimum impact.

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Plectranthus ‘Zulu Wonder’The common Swedish ivy (Plectranthus australis) is another trailing plectranthus. Its glossy, dark green leaves can cascade as far down as 3 to 4 feet. Plants persist effortlessly in hanging baskets and can thrive in either sun or shade. Interiorscapers test this plant’s durability again and again in thousands of restaurants, offices, and mall plantings.

Among the flowering varieties, there are a few that are somewhat available. ‘Zulu Wonder’ has lavender-blue flowers, while ‘Lois Woodhull’ bears beautiful flower spikes of bluish-rose and white from summer until fall. It only grows about 10 to 12 inches tall and has thick, green leaves. For a unique, late-blooming annual, look for ‘Mona Lavender.’ Its stunning late summer display consists of large, lavender-flecked blossoms on contrasting dark stems. The leaves are a glossy dark green on top and burgundy underneath. It can exceed 18 inches in height when provided with ample space.

Consider trying the beautiful foliage or flowers of a plectranthus—they offer a delightful alternative to mainstream annual bedding plants.

George Papadelis is the owner of Telly’s Greenhouse in Troy, MI.

At a glance: Plectranthus

Common name: Swedish ivy

Plant type: Annual (tender perennial)

Habit: Upright and trailing varieties

Plant size: Upright varieties: up to 3 feet tall and wide; Trailing varieties: up to 12 inches tall

Leaf color: Silver, gray-green, green and white variegated, green and gold variegated, green

Leaf size: Rounded, 1 to 4 inches long and wide, depending on variety

Light: Sun to shade

Soil: Well-drained

 Uses: Upright varieties: large containers, annual and perennial borders; Trailing varieties: front of containers, hanging baskets, wall plantings

Companion plants: The many foliage colors compliment a wide array of annuals and perennials.

Remarks: Grown for its foliage, like coleus. Foliage weaves nicely amongst other plants. Upright forms can be easily trained into standards. Size of upright varieties can be controlled with pinching. Silver-leaved varieties prefer more sun.

www.provenwinners.com
‘New Wonder’

by George Papadelis

I can remember a time when commercial growers of annuals had a relatively small list of plants from which to choose. We would order our seeds and then receive rooted cuttings of geraniums, vinca vines, fuchsias, and Rieger begonias. Then came New Guinea impatiens. These quickly became popular and gave us another major crop to produce. But several new annuals have come along that have completely changed the way we garden. Bacopa, verbena, calibrachoa, double flowering impatiens, wishbone flower (Torenia), dahlias, and petunias—all grown from cuttings—have exploded into the marketplace and continue to grow in popularity. Fan flower, or Scaevola, is another wonderful trailing or spreading plant with many uses for the modern landscape.

Scaevola is an enormous genus that contains plants native to Florida, Hawaii, Australia, and many other tropical environments. Some of these are invasive weeds, but the Australian species aemula is the ornamental blue-flowering plant from which most garden-worthy cultivars are derived. Scaevola gets its common name, fan flower, from the arrangement of its petals in a fan-shaped cluster. These form flowers that are arranged in bigger clusters 2 to 3 inches across. The flowers develop on trailing plants and last for several weeks.

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‘Pink Fanfare’www.parkseed.com
‘Purple Fan’www.provenwinners.com
‘Whirlwind White’This long-lasting bloom time keeps deadheading to a minimum and makes fan flower a low maintenance plant. It is typically used in hanging baskets or as a trailing component in combination planters where it may grow 3 to 4 feet long. In addition, fan flower is also a wonderful spreading plant for beds. A single plant can spread to form a mound two or more feet across and about 8 to 12 inches tall.

One of the first fan flowers developed was ‘Blue Wonder.’ It is still very popular and has been joined by several similar blue cultivars like ‘New Wonder,’ ‘Whirlwind Blue,’ and ‘Blue Shamrock.’ These make excellent hanging basket plants by themselves or when combined with complimentary plants. Since each of these has blue petals with a yellow base, try combining them with yellow plants like bidens, Cape daisy (Osteospermum ‘Symphony Yellow’), marguerite daisy (Argyranthemum ‘Butterfly’), or Dahlberg daisy.

‘Zig Zag’ has big, beautiful flowers that are prominently bicolored violet and white. This cultivar blooms several weeks later than others. There are two popular white varieties, ‘White Charm’ and ‘Whirlwind White’ that are also great performers. ‘White Charm’ forms a more compact 12- by 12-inch mound while the latter can grow up to 24 inches wide. These also have yellow-based petals that look great with other yellow plants.

www.parkseed.com
‘Blue Wonder’‘Pink Fanfare’ is one of the few pink cultivars. Its flowers are actually more of a muted lavender color. Plant breeders are working on some new colors and a good yellow variety will likely be introduced.

New plants like fan flower are great additions to the annual palette. Take a bold approach and try some of the new plants that breeders have been working hard to produce. If you have yet to try a fan flower, you and your garden will be very pleased with its performance. Try one in a combination planter, or better yet, drop one into a flowerbed. Maybe you’ll show a fellow gardener how to use a new plant.

George Papadelis is the owner of Telly’s Greenhouse in Troy, MI.

At a glance: Fan Flower

Botanical name: Scaevola aemula (skay-VO-lah EYE-mew-lah)

Plant type: Annual

Plant size: 8 to 24 inches tall and wide, depending on the variety

Habit: Spreading, trailing

Flower color: Violet, purple, white, light pink

Flower size: 2- to 3-inch clusters

Bloom period: Summer

Light: Sun

Soil: Well-drained

Uses: Containers, hanging baskets

Companion plants: Yellow-flowered annuals such as Bidens, Cape daisy (Osteospermum ‘Symphony Yellow’), marguerite daisy (Argyranthemum ‘Butterfly’), or Dahlberg daisy.

Remarks: Also can be planted in the ground to form spreading mound. Fan flower is a tender perennial that is treated as an annual.