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