Cleome, Tall Flowers for the Back of the Annual Border

Cleome (klee-OH-mee) or Spider Flower is a tall plant for the back of the border. Its pink, white, rose or purple flowers open gradually, with the spent stamens developing into long-stemmed seed pods with a spidery appearance. Young palmate leaves mimic Cannabis. Older varieties reach heights of five feet and have sharp thorns hiding along stems to surprise the unwary gardener. Newer cultivars are shorter and have been bred to be thornless.

Cleome grows fast from seed; purchased seedlings may be rootbound and not transplant well. Seeds are best planted in full sun where plants are to grow. Keep seeds moist for three weeks. Plants are heat- and drought-tolerant thereafter.

Cleome reseeds readily but is not invasive. Older stems become leggy and leafless at ground level, so it looks best when planted behind a shorter plant that will hide its base. Older varieties of Cleome flowers have an unusual, lemon-musk fragrance that is more noticeable at dusk. A few people find the scent offensive. Thornless cultivars have lost the scent, too. Flowers attract bees and Sphynx months, large insects that can be mistaken for hummingbirds. Plants are deer-resistant. They look especially nice when planted in large drifts. Self-sown seedlings are often too dense for plants to reach full size. Thin them to a spacing of 12 inches.

To avoid potential for disease, remove plants once they are killed by frost. Rotate plant locations after a few years to avoid attracting harlequin bugs, a relative of the stink bug.

This image shows Cleome buds (top), open flowers (middle) and unripe seed pods (bottom). The long, narrow pods will mature to tan before they burst open to release ripe seeds. Each one of the pods contains 10-15 seeds. Remove the unripe pods if you want to prevent reseeding.

White Cleome pairs well with almost any other flowers

Cosmos - Perfect for a Child's First Garden

Cosmos is a beautiful and easy-to-grow flowering plant known for its bright and showy flowers. Cosmos bipinnatus (KAHS-mos bye-pin-NAY-tus) come in shades of white, pink, rose, red, burgundy and bicolors. Cosmos sulphureus (KAHS-mos sul-FER-ee-us) are shades of yellow and orange. Cosmos are heat lovers, native to Mexico and Central America. Plants have fine, ferny foliage that grow to heights up to six feet.   

They are easy to start from seed and are an excellent choice for introducing children to gardening. Wait until soil has warmed, then scatter seeds where they are to grow and sprinkle with a little soil or rake lightly. Do not cover too deeply. Keep soil moist until germination occurs. Established plants are drought tolerant; they do not like to be overwatered. Plants readily self-seed.

Avoid planting in areas with strong winds or they may require staking. Should tall plants flop, they can be cut back to 12-15 inches and will rebloom in a few weeks. Cosmos attracts bees, butterflies, and hummingbirds, making it a great choice for pollinator gardens.

Clematis - Showy Vine for Trellis, Container, Groundcover

Clematis (pronounced  CLEM-ah-tiss) is a popular flowering vine. There are many species and hundreds of cultivars, with new hybrid introductions coming to nurseries every year. Most are deciduous but fragrant Clematis armandii is evergreen. Most have large, showy, colorful, flat , single or double flowers. A few have hanging bell-shaped flowers, while others have strap-like petals. Try to purchase a new vine while it is in bloom to confirm the color. The label will likely provide pruning recommendations appropriate for that variety.

Clematis tolerates a variety of soil types but prefers a moist, alkaline soil, so be prepared for a light application of lime every fall if you garden in an acid-soil location. They are weak climbers and will look best when secured to a trellis with soft twine. They can also be grown in containers or allowed to scramble along atop the soil.

Clematis cultivars vary in mature size. Typical size is six to twelve feet, with a few extending to thirty feet or more. There are three main classes of Clematis.. Type dictates the pruning method. Type I vines flower in early spring on wood produced in the prior year. They should be pruned immediately after flowering to spur new growth for next year’s flowers. Type II are repeat bloomers that flower on both old and new wood. Cut out dead wood in spring, deadhead throughout the season, then prune again after most flowering has subsided. Type II can be pruned drastically if vines have become overgrown. Type III vines flower later than the first two groups, in late summer and fall. They bloom on both new growth and old growth. Pruning is optional for this group, but vines will be much more attractive if they are pruned down to 12-15 inches in early spring.

Clematis like to grow with “their heads in the sun and their feet in the shade,” which sounds daunting but can be accomplished with a thoughtfully placed large rock, gravel, container, or groundcover plant. Best flowering occurs with at least half-day sun. In the deep South, protect plants from scorching afternoon sun to prevent crispy leaves and faded flowers.

Two of the most widely grown Clematis are ‘Jackmaii’ (vigorous grower with large, flat purple flowers) and ‘Henryi’ (large, flat, pure white flowers). ‘Rooguchi’ has a downward-facing purple bell-shaped flower. Though it is not as eye-catching as the flat-flower types, it is popular because it reblooms freely over several months. Seed heads are interesting pinwheel tufts of fuzzy threads.

 All parts of Clematis are toxic to humans and animals.

Purple ‘Jackmanii’ is one of the most popular varieties of Clematis.

Clematis seeds look like fluffy pinwheels.

A "Pot of Gold" for the Garden - Coreopsis

Coreopsis (pronounced kor-ee-OP-sis) is a group of native perennials with bright, daisy-like flowers and a clumping habit. Most Coreopsis have yellow flowers, but hybridizers have introduced new cultivars with flowers of burgundy, rust, red, or bi-colors. ‘Moonbeam’ and ‘Zagreb’ are two of the best yellows. Coreopsis verticillata has a narrow (“threadleaf”) foliage.

Locate plants in full sun or mostly sun, in well-drained neutral or acidic soil, zones 3-9. Plants attain heights of two to three feet. Individual Coreopsis flowers are small but the plant will cover itself, putting on a show. The size of the flowers make deadheading tedious. Once most flowers have faded, use clippers or hedge-trimmer to decapitate the spent blooms and their stems. Plants will regenerate and rebloom.

Coreopsis tolerates heat and humidity. They attract pollinators but not deer. Their airy appearance makes them a good choice for a cottage garden, a native garden, or children’s garden.

Coreopsis verticllata, Threadleaf Coreopsis

Purple Heart Is An Easy, Colorful Perennial

Tradescantia pallida..

Recent warm weather started the garden-planning process for many of us. If you are seeking a quick-growing,, easy perennial for a splash of violet, consider Purple Heart.

Tradescantia pallida (pronounced trad-es-KAN-tee-uh PAL-lid-duh), commonly called Purple Heart, has striking purple leaves. It is grown for its rich foliage, but it also has delicate, three-petaled pink or purple flowers. It is a popular choice for gardens and flower beds, and can be grown as an annual or perennial depending on the climate, or as a houseplant anywhere.

Purple Heart can reach up to eighteen inches tall and twenty-four inches wide, with a trailing habit. It prefers well-drained soil and partial shade. It will survive in full sun if given occasional irrigation. More sun results in greater color intensity of leaves. Plants are drought-tolerant once established. They are undemanding in soil type or texture.

Propagation of Purple Heart is easy from stem cuttings. Cuttings can be taken in the spring or summer rooted in a mixture of sand and peat moss. For those with no desire to set up a propagation area, fair success can be obtained by taking stem cuttings and inserting them into the soil where the mother plant is growing. Remove any leaves that will be below ground level, and ensure that soil covers a node (where a leaf emerged from the stem). Keep soil damp and at least half the cuttings will strike roots.

Plants are hardy zones 7-11. A hard frost will turn all top growth into mush, which can be removed any time before spring. In the cooler zones, a light mulch (pine needles) will help protect the roots and ensure its return. New growth will emerge as soon as weather warms in the spring. Purple Heart is not particularly susceptible to diseases or pests, including deer. It provides a beautiful contrast to yellow or pink flowers. Its undemanding nature and rapid growth makes it a good choice for new gardeners.

This border of Purple Heart is located outside a church gymnasium in an area that receives full morning sun. It gets no irrigation or care, and it looks great, year after year.

These Snowflakes are Not Meant for Snowmen

Leucojum (pronounced loo-KOH-jum) is an elegant flower with delicate, drooping white blooms that look like petticoats. Spring Snowflake (L. vernum) flowers in very early spring. Summer Snowflake (L. aestivum) flowers mid-spring. Each tepal (think petal) has a blotch of green on it on its tip. Strap-like foliage resembles that of daffodils and averages 12 to 24 inches in length.

Snowflakes do well in part shade to full shade, and perform well under deciduous trees. They prefers dry soil when dormant, with added moisture when in flower. They are tolerant of heavy clay soils. The flowers are all held on the same side of the stem, so they lean gracefully to the side. They have the same gelatinous sap as daffodils, so should not be combined with other flowers in a vase.

Snowflakes look super when planted in large drifts, in woodland settings, or in rock gardens. Bulbs will multiply into good sized clumps. They prefer to remain undisturbed. Congestion doesn’t seem to bother them as long as they receive adequate nutrition from the soil. Add a sprinkle of lime and a little fertilizer each spring to keep them happy. The bulbs can be underplanted in a bed of Mondo Grass (Ophiopogon) or other shade-loving groundcovers.

Deer, rabbits, and voles avoid Snowflakes. They are not damaged by juglone, so can be planted under Black Walnut (Juglans nigra) trees. Bulbs and leaves are poisonous. Do not eat.

A third species, Leucojum auctumnle flowers in late summer to early fall. It is less popular that the spring-flowering types and is difficult to find in garden centers.

Lovely Loropetalum, Chinese Fringe Flower

Amidst all the warm colors of autumn leaves, the deep burgundy or wine-colored foliage of Loropetalum provides a wonderful contrast.

When Loropetalum became widespread in garden centers in the late 1980’s, their deep burgundy foliage and hot pink flowers immediately became popular. White flowered, green-leaf varieties exist, as do variegated leaf cultivars, but neither are as widely grown as the burgundy-leaf forms. Unfortunately, many of the early introductions grew much larger than their labeled mature heights. Warm nights and the long growing season of the southeast result in taller-than-anticipated shrubs. When used as foundation shrubs, these early introductions required aggressive pruning to restrict size. Several cultivars that were labeled at a three-foot maximum height grew five feet or taller. (If I sold you one of these during my sales stint in a garden nursery, please accept my apology. It was a mistake through ignorance, not malice.)

Shearing Loropetalum into tight orbs or square-edged hedges ruins the graceful arching shape. Taller cultivars (‘Zhuzhou Fuchsia’ is a robust one) can be limbed up to tree forms that rival Crape Myrtles, without the concrete-staining problems of Crape Myrtle seed-pods but also without the lovely exfoliating bark of the Myrtles.

Burgundy-leaf types can take on green tints in the hottest part of the summer. ‘Jazz Hands’ is a cultivar with variegated foliage. New growth is splashed with pink and white. With age, foliage shows less and less variegation, so plan to prune annually to force colorful new growth. The variegation shows best when seen up close, so site your specimens where they can strut their individuality.

Evergreen Loropetalum (pronounced lor-oh-PET-ah-lum) is hardy in zones 7-9. It is heat tolerant, easily transplanted, and not choosy as to soil type, although it may show chlorosis in alkaline soil. Avoid boggy soils. Established shrubs are drought tolerant. They are rarely browsed by deer.

Heaviest bloom occurs in spring, but flowers appear sporadically during other months. Similar to Witchhazel, Loropetalum flowers have strap-like petals that give rise to the common name Fringe Flower. All forms bloom on old growth, so if you trim to generate fresh variegation, be aware that flowering will be reduced.

Check plant labels before purchase to ensure the selected cultivar will suit the planned location. If your site is tight, assume shrubs may exceed the stated dimensions.

Strap-like flower petals look like tufts of fringe, leading to the common name Fringe Flower.

Unpruned shrubs have a lovely, arching stem structure.

Easy, Pretty Tatarian Aster

Asters adorn the fall garden with clouds of blue blooms that show to advantage against yellow goldenrod, orange pumpkins, and the warm shades of autumn leaves. The Asteraceae family was one of the largest until those pesky taxonomists got involved. With their penchant for genetic accuracy, they reclassified North American asters into Symphyotrichum, Eurybia, and a number of smaller classes. For an exhaustive (mind-numbing) discussion of Aster’s new family tree, consult the University of Waterloo’s research report by clicking HERE.

Today’s feature plant, Tatarian Aster, was formerly Aster tataricus and is now Crinitaria tatarica (pronounced krin-ih-TAIR-ee-ah tah-tair-IH-ka). Tatarian Aster is a perennial wildflower with soft lavender-blue, star-shaped flowers held in flat-topped groups. The flowers have 7-20 petals each, arranged around a yellow center. Bees, moths, and butterflies love them. They provide a nectar meal for migrating Monarch butterflies.

Tatarian Asters grow in zones 3-9, in any soil type and almost any pH, and require full sun exposure. Plants are resistant to heat and humidity. They may gain heights of up to six feet, but rarely need to be staked unless they are grown in very fertile soil with plentiful moisture. Unless you enjoy staking, take a Tough Love approach to growing this perennial. Plants grown in rich soils with plentiful moisture can spread aggressively.

The height of Tatarian Aster means it is a good back-of-the-border feature. It is especially pretty when grown along the sunny edges of woodlands, paired with Miscanthus, Muhlenbergia, or other grasses. Deadheading spent blooms will lead to a lengthy flowering season, from late summer all the way to freezing temperatures. In winter, cut the dead foliage back to ground level.

Want pollinators? Plant Zinnias.

Zinnias are one of the most common annuals and have been popular since the 1920s. They are easy to start from seed, are undemanding as to soil, and bloom non-stop from spring through frost. They tolerate heat and moderate drought. The only thing they demand is a full sun exposure. Zinnias come in every color of the rainbow except for blue, including bi-colors and even tri-colors.

Zinnias are categorized into three groups: tall, with long stems, best for cut flowers or the back of the flower bed; short, best for mass plantings in beds or borders; and creeping or spreading, which do equally well in flower beds and containers. Tall varieties may reach heights of 36 inches or so. Flowers can be single or double, and may resemble dahlias or cactus. Cut flowers last a long time in the vase, but remove any leaves that will be below the waterline.

My favorite bedding type is the Magellan® series, which I start from seed every year. Magellans are mildew resistant and have the sweet habit of layering new foliage and fresh blooms on top of the spent blooms. Short internodes (stem space between leaves) mean that spent flowers are concealed by fresh blossoms, reducing the need for dead-heading but also means they are difficult to use as cut flowers.

Lovely pink Magellan Zinnia

Spent blooms are concealed by new leaves and flowers. A little Downy Mildew spots the leaves.

Of the creeping type, the Profusion® series is well named, with a multitude of small blooms on plants that are resistant to Powdery Mildew. Mildew doesn’t affect the flowers, but can make the foliage spotted and ugly. Combat this problem by planting all varieties in locations with good air circulation. Keep the foliage dry when watering – a perfect application for soaker hoses. Avoid boggy soils and over-fertilization, which can result in more leaves and fewer flowers. 

Zinnias do not tolerate frost. Seed can be direct sown once weather has warmed in spring. Plants will grow rapidly to flowering size. I prefer to start mine in peat pots so that I can space them exactly in my flower beds. Why peat pots instead of plastic 4-packs? The baby plants dislike root disturbance.

Some seed catalogs sell Zinnias by separate color, while others only offer a mix. I like to select specific colors, reflecting a different color scheme each year. It is hard to select my favorite combination. Red, pink, and white looked spectacular in the Mary Snoddy garden one year, but then salmon, yellow and purple looked fabulous the next. Seeds can be saved from year to year, but hybrids rarely mimic their parents.

Zinnia flowers are beloved by butterflies and bees, so I filled all the empty spaces between perennials in my new pollinator garden with mixed colors of Magellan. The pops of color will last until frost.

A butterfly enjoys a green and pink bicolor Zinnia, ‘Queen Lime’. Photo by jggrz from Pixabay

A composition of assorted Zinnia colors.. Photo by MrGajowy3 from Pixabay

Tall Zinnias, grown for cutting, can look a little gawky. Site them at the back of the border to conceal their lower sections.

Persian Shield (Strobilanthes)

Persian Shield (Strobilanthes, pronounced stroe-buh-LAN-theez) is a heat-tolerant, tender perennial treated as an annual in zones 8b and colder. It has lavender flowers, but is grown for its foliage: deep green overlaid with bright purple and a metallic sheen. The foliage is beautiful in its own right, but when combined with other plants, especially pink or purple flowers, it makes them sing. It is ideal in a larger container. Provide rich, well-drained soil with plentiful moisture. When too dry, the leaves will droop. If a wilted plant is watered immediately, it will perk back up but too many repeats will result in leaf drop. Constantly wet soil will cause root rot.

Persian Shield will grow into a loose shrub up to 36 inches tall and 24 inches wide. It is much more attractive when the stem ends are pinched regularly to make a shorter, bushier plant. New growth is more colorful than older leaves. The plant looks best in partial shade. Too much sun will make leaves crisp around the edges; too little light makes them look faded.

Persian Shield is easy to propagate from stem cuttings or layering. It will survive in my home as a houseplant or in my greenhouse through the winter, but reduced light results in a spindly plant. I overwinter one specimen, then use it as a mother plant for several cuttings in spring. Rooted cuttings grow rapidly. Plants are occasionally attacked by spider mites.

A 14-inch container planted with a single Strobilanthes plant. The newest growth is distinctly more colorful than the older leaves.

A favorite combination: Persian Shield paired with purple Angelonia and red/purple bat-faced Cuphea. Next year I will select a glazed container rather than this terra cotta, to reduce evaporation and the need for daily watering. This photo shows the solid purple reverse side of the Persian Shield leaves.

Sturdy Spireas for Spring Color

Spirea was one of the first shrubs whose name I learned as a child. There was an enormous plant next to our kitchen door. In early spring, it was covered with clusters of white blooms on arching stems. It had almost no scent, but the flowers were impressive although short-lived. When I asked my mother what kind of “bush” it was, she told me (semi-accurately) that it was a Spirea Van Hootie. Now I know that it was a Spirea x vanhouttei. Moving to the front garden, I asked her for the name of a shorter shrub with deep pink blooms.“Spirea,” she responded. “How can this be Spirea if the other one is Spirea,” my six-year-old self inquired, “because they’re not the same color and they’re not the same size and they don’t look alike.” Her response: “Go ask your father.” (A lot of our conversations ended this way.) As an adult, I realize the smaller, pink-flowered cultivar was ‘Anthony Waterer,’ one of the oldest and still one of the most tolerant of heat, poor soil, and bad pruning.

As a genus, Spireas are hardy and long lived. There are numerous species, and new cultivars seem to arrive on market every year. Sizes range from tiny to giant; flower colors can be pink, white, or red, and can occur on branch tips or all along the stems. Old varieties have narrow blue-green leaves that neither impress nor disappoint. Some of the newer cultivars have brightly colored foliage which extends the beauty season beyond the bloom period. In the Mary Snoddy garden, a pair of Spirea japonica ‘Limemound’ throw bright yellow foliage in early spring, which darkens to a lime green when weather turns hot. Limemound has bright pink flowers that scream for attention against the yellow foliage. Viewers either ooh and ahh or walk away muttering something that might be “eyesore.” The Limemound’s foliage turns orange in autumn and then sheds entirely, leaving a winter framework that resembles a jumbled ball of sticks. I underestimated the mature size of these shrubs (three feet with an equal spread), so I am forced to prune hard every winter to keep them within the bounds of available space. This major pruning has no evident impact on the plants’ health.

Among the white-flowered variety, Spirea nipponica ‘Snowmound’ is a 3–5-foot shrub that looks like a fireworks display when in bloom. If you have space, old Van Hootie, Spirea vanhouteii will grow to ten feet tall and twelve feet wide. Nurseries may label the vanhouteii species as “Bridal Veil” or “Bridal Wreath” Spirea, but these terms are also used in marketing Spirea prunifolia and Spirea cantoniensis, similar but smaller in stature.

Spireas bloom heaviest on young stems, so pruning will force new growth and result in more flowers the following year. Pruning should be done as soon as the flowers fade and fall. Cut stems to varying lengths with hand pruners rather than using hedge trimmers to create a round ball. Plants are most attractive when one-third of the oldest branches are cut back hard and the remainder are pruned lightly. This maintains their graceful arching appearance. These shrubs look best when grown in groups or hedges rather than as single specimens. They perform well on slopes where mowing is treacherous.

Spireas tolerate most soil types and will withstand half-day shade, although flowering is better in full sun. Avoid wet sites. Most species are cold hardy zones 5-9 or even colder, but check the plant tag to confirm zone for your selection. They are rarely bothered by diseases, insects, or deer.

Spirea japonica ‘Limemound’ elicits comments that range from “Outstanding” to “Yikes!”

A close view of Spirea cantoniensis ‘Reevesiana’ flowers

A young planting of Spirea cantoniensis ‘Reevesiana,’ perfectly sited at the top of a steep bank near a creek.