Welcome to the Garden

Notes from the Garden - May June July 2012

by Harvey Cotten

As spring flows into summer, some of the Garden’s most spectacular collections begin to show their rich colorful display. In May, the many choices of hydrangeas come to life in various shades of pink, blue, and white. As June heats up, so do the colors of daylilies that adorn our spectacular Daylily Garden. These hot colors of red, yellow, orange and purple truly shine in the bright summer sun. As the dog days of summer approach, crapemyrtles planted throughout the Garden thrive in the heat and humidity found during a July day.

May: Hydrangeas / June: Daylilies / July: Crapemyrtles

May: Hydrangeas
Planted throughout the Garden are numerous cultivars of hydrangeas that begin to flower in May. There are three primary species that bloom during this time of the year with many choices available within each species. Hydrangea macrophylla, bigleaf hydrangea, Hydrangea quercifolia, oakleaf hydrangea and Hydrangea arborescens, smooth hydrangea are the major players.

Bigleaf hydrangea (H. macrophylla) is arguably the most popular hydrangea sold in garden centers today. These hydrangeas are also called mopheads or lacecaps depending on the flower type present on each plant, and generally we can find blooms in colors of pink, blue or white. Bigleaf hydrangea is native to the Far East and was introduced into the United States in the early 1800s. They have been planted in southern gardens for years and have long been considered one of our heirloom plants.
One of the unique aspects of bigleaf hydrangea is the ability of the gardener to influence the color of your flowers. This particular plant tends to have pink flowers when the pH of the soil is above 6.0. When the pH drops below 5.8, then this hydrangea tends to have blue flowers. The determining factor is the availability of aluminum in the soil and that availability is regulated by the pH of the soil. Soils in this area tend to be acidic, so we primarily see more blue flowers than pink in the landscape. Adding aluminum sulfate or ground sulfur to the soil lowers the pH, while adding lime raises the soil pH, so you can influence the color of your flowers.

One of the reasons the bigleaf hydrangea has become so popular in recent years has been the introduction of new cultivars that have extraordinary garden performance. One of the problems that we have experienced over the years is losing the flower buds to a late spring freeze. This hydrangea is very winter hardy but it does tend to come out of dormancy quite early with any warm days in February or March. The flower buds become exposed and, if we have a late spring freeze, they may be killed while your plant is not harmed in any way. This can be quite frustrating for that means no flowers for this year. With the introduction of the ‘Endless Summer’ hydrangea, this problem has been overcome, since this is what is known as a remontant (reblooming) hydrangea that has the ability to set flower buds on last years’ growth (old wood) as well as this year’s growth (new wood). This overcomes the problem of late spring freezes as well as extending the bloom season well into the fall of the year. While ‘Endless Summer’ is an excellent choice, I would also recommend ‘Penny Mac’, ‘Mini Penny’, ‘Oak Hill’, ‘Dave Ramsey’ and any of the ‘Let’s Dance’ introductions. For a re-blooming lacecap type selection I would recommend ‘Twist and Shout.’

One of my favorite native shrubs is oakleaf hydrangea (Hydrangea quercifolia) and it really stands out in May with its beautiful white panicle flowers against the coarse textured foliage. You will find oakleaf hydrangeas growing throughout the Garden, especially along woodland areas such as the Dogwood Trail, Nature Trail, and Azalea Trail. Two particular spots I love to show off oakleaf hydrangeas are along the west side of the Central Corridor Garden right after entering and beginning to walk down the brick path. There is a large planting of the cultivar ‘Snowflake’ which has to be my favorite selection. The flowers of Snowflake hydrangea are double and can be up to eighteen inches long, creating a shrub that becomes weeping in habit. The other spectacular planting of oakleaf hydrangeas runs along the east side of the creek bordering the Nature Trail. It is best viewed from the Daylily Garden and is breathtaking in bloom.

The great part about oakleaf hydrangeas is that they are truly a multi-season plant. After the pure white flowers of late spring and early summer mature into differing shades of rosy pink to cream, the foliage turns into brilliant shades of red, purple and russet brown in fall. After several hard freezes the foliage falls off exposing the beautiful patterns of exfoliating bark in the winter months.

While there is nothing wrong with planting seedlings of the oakleaf hydrangea, I highly recommend some of the outstanding cultivars that have been introduced. ‘Snowflake’ is at the top of my list, but ‘Snow Queen,’ ‘Pee Wee,’ ‘Harmony,’ ‘Alice,’ ‘Amethyst’ and now ‘Ruby Slippers’ are worth consideration.

The last hydrangea we see blooming during May is the smooth hydrangea (Hydrangea arborescens). Native to woodlands of the Southeastern US, this shrub has a white snowball type inflorescence. The most popular cultivar found in gardens is ‘Annabelle,’ whose large snowball flowers begin lime green and open a pure white the size of a softball. As the flowers fade in late June they take on a creamy shade of tan and can be dried very easily. Recently, there have been two exciting introductions of H. arborescens that have captured the attention of gardeners everywhere. First, ‘Incrediball’ came on the scene with pure white, snowball flowers that are the size of a small soccer ball – they are huge! I must say that I did not think the stems would be strong enough to support these blooms but so far I have not seen any problems. The other introduction is one called ‘Invincible’ a pink flowering cultivar.  While introducing a different color to the landscape, the introducing company, Proven Winners has announced a portion of the sale of each plant will be donated to the Susan B. Komen Foundation for Breast Cancer Research.

June: Daylilies
    As the long, hot days of June roll around, our outstanding Daylily Garden comes into full bloom. If being surrounded by a riot of color is exciting to you, then our Daylily Garden in June is just the place for you. Over 800 different cultivars of daylilies are planted in this large display garden and they run the gamut of flower size, type and color that daylily hybridizers can dream of creating. Walk through this incredible garden and see some of the most dependable herbaceous perennials one can grow in the South. 
    Our Daylily Garden is recognized by the American Hemerocallis Society as one of their sanctioned Display Gardens in the United States. This garden was one of the original five gardens that was planted and maintained by volunteers back in the 1980s  and has long been one of the most colorful botanical displays you will find in the Garden. Be sure to visit so you can see which daylilies will be available in the fall at the annual Daylily Sale that helps support the purchase of the latest hybrids for our collection.

July: Crapemyrtles
    As the Dog Days of summer seem to sap the strength out of most everyone, plants, people and pets included, it appears that the crapemyrtle stands strong against the heat and humidity of this month. No matter how hot, dry or humid the weather may be, crapemyrtles flourish during our Alabama summers and provide a wide range of color and sizes in the landscape. Crapemyrtles have been called the “lilac of the south” for the incredible ruffled blooms in varying shades of white, pink, red and purple that can provide color for more than 100 days. 
    The interesting thing about crapemyrtles today is that we have plants ranging in size from two feet tall all the way up to thirty feet tall. It is important that you first decide how tall a plant to grow in your chosen location. Once you have decided on the mature height that you desire, then you can pick out a color and that will tell you which cultivar is suitable for your conditions. Always follow this pattern of selecting and you will be rewarded with knowing you have put the ‘Right Plant in the Right Place.’ 
    Crapemyrtles were introduced to America during colonial times and have been growing throughout the south since then. However, it was after Dr. Don Egolf of the National Arboretum did extensive hybridizing work during the 1960s and 70s that crapemyrtles have flourished around the country. What Dr. Egolf created were cultivars that had the following characteristics: better cold tolerance, improved disease resistance, incredible variety in bark color and range of sizes suitable for all garden situations. Over 25 different crapemyrtle selections have been introduced through the National Arboretum and you can recognize them, for they have a Native American tribal name as the designation. My favorites include ‘Natchez,’ ‘Sioux,’ ‘Biloxi,’ ‘Hopi’ and ‘Osage’ but all are worthy of consideration.
    Recently, there has been great interest in breeding smaller crapemyrtles for home landscapes. For years, the bright red flowering ‘Victor’ has graced the east side of Botanical Drive and has always drawn the admiration of visitors entering the Garden. Pocomoke’ is a beautiful pink flowering form that adorns both sides of the pathway leading to the Children’s Garden and Nature Center. One of the best new red cultivars ‘Cherry Dazzle’ can be found at the Garden of Hope. 
    For a plant that can thrive in full sun, is very drought tolerant once established, and has very few pest problems, it is hard to find a more suitable plant than crapemyrtle – as long as you put the proper sized one in your garden spot.