Congenial Perennials

Investing in lush and colorful displays

Robert Clark

Perennials are basically plants that last two years or more as compared to annuals that only last one season. Spring and summer blooming perennials bloom during the warm season and then die completely back to the ground. The next spring they emerge from their roots and begin to grow and bloom for the next season. These are usually referred to as herbaceous perennials and are what we see in our local nurseries and garden centers. A good example of this type of perennial is Rudbeckia hirta, or black-eyed Susan, which dies back to the ground after the first heavy frost and then re-emerges every spring. Plants can grow as annuals in some climates and perennials in others. A class of perennials called evergreen perennials retains a mantle of leaves all year, such as Saxifraga stolonifera, commonly called strawberry begonia. This perennial grows like a ground cover with evergreen leaves and blooms that appear in early spring every year.


How to Plan a Perennial Border

Numerous themes and designs should be considered when planning a perennial border. It is important to match the style of your perennial border to the style of your house and existing garden. Perennial gardens are not low maintenance and will need monthly attention. If planted properly, these perennials will add ever-changing color and interest to the landscape. If planted in a haphazard way, a perennial garden can be one giant mess.

Order is important in all garden types and particularly so when designing a perennial garden. Perennials require a strong background, which can be an evergreen hedge, a trellis fence, or a beautiful brick or stucco wall. These backgrounds will add structure to the garden — an important component in the successful overall design. Perennials without a strong backdrop can look haphazard and messy. Choose your background first. If you are lucky enough to have a wall as a backdrop, consider adding fig ivy or a wooden trellis to further enhance the structure. A focal point — such as a statue, birdbath, bird house, or fountain — adds interest to the perennial garden so that it will still offer something pretty to see when most of the plants are dormant.

The next consideration is how to arrange and plant the perennials. Will they be planted in large swaths? Will the perennials be planted in color blocks? Will the plants be in their chronological order of bloom time? Symmetry is important in a perennial design. It is imperative and logical to plant the taller plants in the back, the medium-sized perennials in front of them, and then the smallest plants in the front. Also, consider when the plants will bloom so that you will have a balance. You don’t want all of the blooming plants to be on the left side of the border in the spring and all of the summer blooming plants to be on the right, for example. Mix the plants up so that blooming plants are on all sides and positions of the perennial border during the blooming season.

If your border is deeper than 3 feet, be sure to add a walkway or path for access through the perennial border. If the border is more than 6 feet deep, it is advisable to have a walkway through the length of the border to allow access for pruning and maintenance. It is wise to use stepping stones or brick or pebble walkways large enough to accommodate a wheelbarrow, or you will end up stepping on the plants when doing maintenance. Consider adding a ground cover, such as blue star creeper or creeping thyme, to grow between the stepping stones and soften the edges of the stone walkway.


How to Prepare the Perennial Bed

Soil preparation is just as important in gardening as sanding is for painting. If the prep work is not done properly, the end result will not be satisfactory. Choosing a site for the perennial bed is also key. Most perennials that thrive in our Zone 8 climate are sun lovers. So, choose a spot that will receive at least six hours of sunlight a day. Morning sun exposure is always preferential to the blasting afternoon sun. Also, look for a spot that is relatively level to avoid standing water that could drown the plants. Ideally the new site has decent soil that will only improve with amendments. It is sometimes difficult to prepare a site properly that has been compacted for a long period of time.

Now, grab your gloves and pointed shovel and start shoveling! Define the outline of the bed with paint. Start at the edge and work your way in, shovelful by shovelful. Dig and turn over the soil. Then dig deeper and turn it over again. Use a stiff garden rake to level the bed and remove any rocks, large dirt clods, or weeds. Add soil amendments such as mushroom compost, Erth Food, and bone meal. Work in the amendments by turning the soil again. Rake it once again so that the soil is level and drains away from any structure such as a wooden fence or house foundation. Use a hose and sprinkler to wet the soil to see if any low areas hold water and need to be leveled. Once this is completed, stand back and admire your perfectly prepared perennial bed that is now ready to be planted.


Choosing the Plants

This is both the fun part and the most daunting part because so many beautiful and interesting choices are available. You simply have to cull your list somehow. Decide to have a particular color scheme such as white, blue, and yellow, or select a brighter scheme including orange or pink. Think about the time you want your perennial garden to be in full bloom. If you spend all summer at the beach, you do not need to have perennials that are at their peak in July. In that case, concentrate on spring and fall bloom. If you would like to have blooms most of the year, choose early bloomers, mid-season bloomers, and late bloomers. You can also augment the bloom by adding spring blooming bulbs such as hyacinths, tulips, and daffodils. The sky is the limit. To help out with your choice, here is a list of favorites.


The Tall Ones

Salvia leucantha – Mexican bush sage – A tall perennial that can grow to 48 inches, Mexican bush sage is one of the most attractive sages. It is easy to grow and is covered with velvety purple and white flowers during the months of August and September. The silver tint of its elongated leaves is a wonderful contrast to the deep-colored blooms. Another added benefit of this carefree plant is that once it is established, it needs very little irrigation.

Crocosmia – montbretia – Crocosmia is a medium to large perennial with long strappy leaves and bright orange, red, or yellow blooms that look very much like orchid blooms. Crocosmia thrives in the hot temperatures and bright sun of our summers in the Midlands. One particularly attractive, red flowering cultivar is ‘Lucifer.’ This prolific plant will be ready for division after a few years.

Buddleia – butterfly bush – Buddleia is an all-time favorite perennial, with many varieties. I prefer the davidii cultivars that produce white, blue, or purple flowers. Buddleia prefers full sun but can adapt to a spot with light shade. It blooms from late spring to late fall. Butterflies flock to the blooms as well as bees. Butterfly bush can grow to 5 feet tall and 5 feet wide, so make sure it is planted in a place where it can spread its branches and thrive.


The Mid Levels

Echinacea purpurea – purple coneflower – Echinacea is a medium-sized perennial that can reach 3 1/2 to 4 feet tall and 1-foot wide at maturity. No Southern perennial garden is complete without a clump of purple coneflower. These tough, daisy-like flowers can range from light lavender to dark purple. Coneflowers bloom from May until the first hard frost in November. The plants are tough and stand upright all summer. The flowers are wonderful for cutting and will last a long time in a colorful arrangement.

Phlox – Phlox is a large genus of flowering plant. Many phlox are prone to mildew in a hot, humid climate. One variety seems to be more resistant to mildew, Phlox paniculata, also known as garden phlox. This is the one and only type of phlox that I recommend for gardens in the Midlands. Garden phlox grows to a mature height of 24 to 28 inches. Most varieties are slightly fragrant, particularly in the evenings. Garden phlox blooms from June thru August in our climate. Blooms can be white, pink, salmon, or light red. Pruning the dead blossoms can prolong the blooming period.

Shasta daisy – Shastas are a classic perennial to add to the border. They grow in clumps from 2 to 3 feet tall and 1 to 2 feet wide. They bear all white petals with bright yellow centers. The strong stems display dark green leaves. Shasta daisies emerge from their dormant state in late May. They start blooming in June and will continue to beautify the garden with their fresh blooms until the heat gets to them in mid to late August.


The Littles

These are the shortest perennials and ones that I consider to be suitable for planting near the edge of the garden in the front or beside any walkway that you may include in the perennial border.

Stachys byzantina – lambs’ ear – This is a wonderful edging plant because of its silver, velvety leaves and mounding form. Lambs’ ear is a soothing companion for other perennials with blue blossoms and can have a cooling effect during the hot summer months. One variety that is particularly successful in Zone 8 is ‘Helen von Stein.’ It grows to 8 inches tall at maturity and 15 to 18 inches wide. It has large, fuzzy silver leaves and a uniform, mounding habit. It is non-blooming so it needs no deadheading or pruning.

Gaillardia x grandiflora – blanket flower – Gaillardia is a tough, bright blooming perennial that grows to a mature height of 10 feet. This is one strong, little plant with very bright blooms. It is not for the faint of heart. It demands attention in the perennial border when it is in full bloom. It thrives in the drought and the heat. It is a great choice for edging a perennial border, and its bright yellow or red blossoms are a dramatic contrast to other brightly colored blooms. It blooms from May until the first hard frost in November. It responds well to deadheading, which also keeps the plants looking neat and tidy.

Heuchera – coral bells – Heuchera are mainly grown for their foliage. The plants consist of palmated leaves with jagged or rounded edges. Varieties are available with dark purple, chartreuse, variegated, and striped leaves. Heuchera are wonderful to use as border plants because they grow in a mounding fashion and only get to be 8 to10  inches tall. I particularly like the chartreuse variety. The bright green leaves are a wonderful contrast to other perennials with purple or blue flowers.


Perennial Garden Maintenance

Many gardeners hope that perennials will be maintenance free. Unfortunately, as with most gardening, that is not the case. During the growing season and the dormant season, perennials and perennial borders will be much more attractive with a little attention. Perennials look neater if pruned after they bloom and cut down to the ground after the first hard frost. Wait until all of the perennials are killed back to the ground. Then prune all of the dead material from the plants. Rake the bed and apply a nice, insulating layer of mulch or pine straw. This will make the perennial bed look neat through the dormant season and will also protect the plants during the cold winter weather.

Perennials also respond well to division when the clumps grow too big. Fall is a great time to divide the clumps. Share your extras with your gardening friends or find another spot to start another perennial border in your garden.


Gardening Chores for the June Gardener

• Most of the spring pruning should be completed by June so you don’t interfere with next year’s bloom.

• Now is a good time to sow zinnia seeds in a sunny, well-drained bed to have blooming zinnias in August.

• If you want to try dahlias in the garden, now is a good time to plant the tubers.

• Deadhead annuals to keep them neat and to encourage new blooms.

• Fertilize annuals with a water soluble fertilizer such as Miracle-Gro.

• Monitor the irrigation system. Check for leaks and blockages.

• Reset outdoor lighting timer to reflect the longer daylight hours.

• Cut back any plant material that has grown over outdoor lighting fixtures.

• If azaleas or any other flowering plants look like the leaves are turning yellow, use water soluble Ironite to help the leaves maintain a dark green color.

• Move the rest of your indoor plants outside for some fresh air and sunshine. Rinse the dust off with a light spray of the hose, and place them under a shady tree.

• If any perennials become leggy and start to flop, install plant stakes or cages to keep them upright.

• Trim any branches that are shading sun-loving perennials.

• Enjoy the last few cool days in the garden.


What’s Blooming?

Bottlebrush, butterfly bush, crape myrtle, gardenia, magnolia, mock orange, oakleaf hydrangea, rose, salvia, butterfly weed, canna lily, cleome, coreopsis, cosmos, daylily, gaillardia, phlox, hosta, impatiens, lantana, purple coneflower, Shasta daisy, snapdragon, stokesia, verbena, yarrow