Powell Gardens' Spectacular Summer Flowering Shrubs

There's nothing like a border of summer flowering shrubs to brighten up these sun saturated days. We often think of spring flowering shrubs but there are good choices for all seasons and here are some of the best shrubs for flowering NOW!

The border near the trolley stop of the Rock & Waterfall Garden is currently at peak bloom with hydrangeas and rose-of-Sharon; two of our most brilliant summer flowering shrubs.

The border contains our best display of Limelight Hydrangeas (Hydrangea paniculata 'Limelight'), which is just now transforming from lime green to white as the flowers mature. Limelight's flowers are mostly sterile, which gives it that full look but does not provide much for beneficial insects and wildlife like the fertile "lacecap" types. All paniculata hydrangeas are easy to grow in our climate and are very forgiving of bad weather and bad pruning. They bloom on new wood so can be cut back in spring for huge blossom stalks OR they can be allowed to grow into large shrubs; many can even be trained (pruned up) into delightful little trees.


The cultivar 'Quick Fire' is an early blooming and fertile lacecap cultivar (in full white bloom back on the solstice) and has already aged to a lovely rosy-pink, soon to deepen to deeper tones
--a quick fire indeed.

The cultivar 'Unique' is a spectacular white, fertile variety that attracts many beneficial insects to its pollen and nectar. What a spectacular choice for a white, evening or moon garden! This mass is in the Perennial Garden but it can also be seen in mass on the Island Garden.

The cultivar 'Pink Diamond' is also in full bloom now and will soon age to a good pink. It is also a fertile "lacecap" type that is a good insectaries garden plant (will attract many beneficial bugs to your garden to help control the bad bugs!). This picture is from the Island Garden (a nice contrast to purple-leaved Diabolo Ninebark to the left). We also have a mass of Pink Diamond Hydrangeas in the Perennial Garden.

Here is a closeup of 'Pink Diamonds' lovely flowers: note the big sterile white flowers set about the smaller fertile flowers inside that have the pollen and nectar for the good bugs.

Rose-of-Sharons (Hibiscus syriacus) is also a spectacular shrub now in bloom. Yes these are hardy, first cousins to the tropical hibiscus and the perennial rose mallows. The cultivar 'Blue Satin' is depicted from near the Rock & Waterfall trolley stop. Our favorite blue-flowering cultivars are 'Bluebird' and 'Coelestris' but they are difficult to find at nurseries anymore. Rose of Sharons become large shrubs 8 to 12 feet tall. Their drawback is that many cultivars self-sow wildly in gardens (luckily not in undisturbed soils so are not considered invasive).

The white-flowering 'Diana' Rose-of-Sharon is a hybrid from the National Arboretum that sets no (or very few) seeds. This is a premier evening garden plant because Diana also holds her flowers open at night while many Rose-of-Sharon close up in the evening. Other sterile National Arboretum Rose-of-Sharon are 'Aphrodite' with pink flowers and 'Helena' with lavender flowers; both good choices where you want the great bloom but NO seedlings to pull.

The Butterfly Bushes (Buddleia davidii) are spectacular this season as none of them died back with the mild zone 7 winter here. This is the cultivar 3-in1 which sports white, pink, mauve and dark indigo flowers. It should be called four-in-one and this shrub is in a "white phase" as these shrubs can sometimes flower mostly one color then another! This is a neat conversation piece shrub and the butterflies love it. It is NOT grafted and literally sports out various colors of flowers through the growing season.

The first picture of 3-in-1 Butterfly Bushes was taken on the west side of the Island Garden's pools: here's what the 3-in-1 Butterfly Bushes on the east side look like! These are a wider mix of colors though the one in the foreground is also in a white phase. Purple Coneflowers make a nice companion planting.

Autumn Sage (Salvia greggii) is a Southwestern native shrub long considered hardy only in zones 7 or warmer. Newer cultivars like 'Furman's Red' depicted have proven hardy here and are actually small shrubs that bloom all summer with peak bloom in the fall. They are a hummingbird favorite and appreciate a dry, well-drained site as shown in the Island Garden's living wall.

The Summersweet Clethras or Pepperbushes (Clethra alnifolia) are also in bloom now. This is a full shrub of the new Plant of Merit cultivar 'Ruby Spice' on the Island Garden. Its wonderful aroma perfumes the walkway along the Island Garden, much to the delight of visitors. Summersweet Clethras are superior shrubs for Evening Gardens for this reason.

Here is a closeup of 'Ruby Spice' clethra's flowers. If only we could transmit its scent through the Internet. Most Summersweet Clethras are white flowering but 'Ruby Spice' is the best pink flowering cultivar. Clethras can range from short 4 foot shrubs in the cultivar 'Sixteen Candles' to tall 8 foot plus if you buy the plain species. They are native to Coastal regions of the eastern United States and Canada and are very hardy into zone 4. They like extra moisture so are great rain garden shrubs.

The mild winter also allowed the Crape Myrtles (Lagerstroemia spp.) to gain more size again. Almost all Crape Myrtles now on the local market are new hybrids that have improved hardiness: Great flowers from the more tender L. indica and improved hardiness from the chestnut-barked but poorer flowering L. faureri. Most of the new hybrid crape myrtles have Native American names but not all. The cultivar depicted is 'Catawba' which is the best purple-flowering variety we can grow. Look for Catawba Crape Myrtle in the Perennial Garden.

The cultivar 'Zuni' has lavender pink blooms and is in full bloom just outside the Visitor Center. Crape Myrtles will not set bud until warm nights of 70F! They need hot weather to perform so are right at home here. (It's one thing that you can't grow well in London or Seattle!) They are marginally hardy and will die back if it is colder than -5F or so. They bloom on new wood so will return and bloom from the roots if they are killed by winter. Many crape myrtles are reaching unprecedented heights of 20 feet in Greater Kansas City as recent winters have not killed them back: long time gardeners have told me that this has never happened here before. I still warn new gardeners that they could so don't count on them as small trees even though many big box stores sell them as such. They are one tough, spectacular summer blooming plant; oblivious to heat and drought. They come in a wide array of colors from white ('Acoma' -- a Plant of Merit) to pink ('Hopi'), red ('Dynamite' may be the best red) and all shades in between. Newer cultivars may also have dark burgundy leaves that really make the flowers stand out.

All photographs taken Sunday, July 27, at Powell Gardens.

Perennials Post-Solstice Peak at Powell Gardens

A stroll through the Perennial Garden, Island Garden and Fountain Garden areas will reveal a riotous array of blooming perennials. I would say now is the peak of color but we have great displays with masses of blooming perennials through fall.
This glowing mass of Missouri Coneflowers (Rudbeckia missouriense) has a few Orange Coneflowers (Rudbeckia fulgida) that really look orange when planted with the more yellow Missourians. This photo is from the Prairie Border in the Perennial Garden. Missouri Coneflower is a choice perennial "Black-eyed-Susan" that is just now becoming a valuable "mainstream" perennial. Orange Coneflower was made popular by its cultivar 'Goldsturm' even though the wild Missouri form is depicted here.
Sahin's Early Flower Sneezeweed or Helen's Flower (Helenium) is one of our longest blooming perennials. It is a hybrid of the native Sneezeweed (Helenium autumnale). Native Americans called the plant sneezeweed because they made a snuff out of it that would make you sneeze to rid your body of evil spirits. It does not cause you to sneeze otherwise!

The Hardy Hibiscus or Rose Mallows (Hibiscus spp.) are riotous and tropical-looking in bloom. This is our favorite: Pink Clouds Hibiscus. All hardy hibiscus are hybrids of our native Rose Mallows. Look for this one in the Perennial Garden.

Disco Belle White Hibiscus may be an older cultivar but it is valuable for its compact size and abundant bloom. Look for this mass in the Perennial Garden.

Disco Belle Rosy Red Hibiscus has very nice pink-red flowers of beautiful texture. Look for this old cultivar in the Perennial Garden.

Lord Baltimore Hibiscus is probably our most dramatic of all the cultivars! This huge mass in the Perennial Garden is over 6 feet tall. There are many, many new cultivars of Hibiscus on the market, some of which are not as good as the classics. Everyone wants to buy something new!

The white mass of flowers in this shot is White Swan Coneflower (Echinacea purpurea). We have received many comments that this cultivar is not hardy but we have had good luck with it -- this mass near the Visitor Center is on its third year.

The Butterfly Garden borders around the Fountain Garden are reaching spectacular bloom. Here native Prairie Blazingstar (Liatris pycnostachya) spires above Adonis Blue Butterfly Bush, Verbena bonariensis and Powell Purple Rose Verbena. You can even see an artichoke at the lower left!

This exuberant image of Perennials in the Butterfly Garden reveals bluish Anise Hyssop (Agastache hybrid --lower left), Purple Coneflowers (Echinacea purpurea wild form -- Center), Black-eyed-Susans (Rudbeckia hirta cultivar -- mid-right), towering Rattlesnake Masters (Eryngium yuccifolium --center back in white), and a huge clump of Sweet Coneflower (Rudbeckia subtomentosa -- budding yellow) back left.

With the Fountain Garden in the background our Perennials are creating quite a splash! There is no better time to visit Powell Gardens and see colorful perennials -- this is just the "tip of the iceberg" in what you'll see and you can cool off afterwards in the fountain if you wish.

All photographs taken by Alan Branhagen on July 21, 2008.

Containers in Color

We are a month past the Summer Solstice and the summer annuals and tropical plants are full sized and exuberant at Powell Gardens! Here's a brief show of some of our containers and plantings...

This container in the Perennial Garden (by former Senior Gardener Jay Priddy) is one of my favorite. It contains the three "classic" elements of container design: thriller, filler, and spiller. The thriller is hare's tail grass (Lagurus), the filler is a cultivar of black-eyed-susans (Rudbeckia hirta) and the spiller is Margarita Sweet Potato (Ipomoea battatus). The use of a grass and a cultivar of a native wildflower really speaks to our region of native grasslands.

The Chapungu Sales tent covers part of our terrace beds outside the Visitor Center but the remaining corner functions as a container. The dramatic use of a Variegated Fucrea (Fucrea)"thriller" and shocking 'Crystal Palace' red geraniums makes quite a composition. The crisp stone edging to the bed makes use of a "spiller" obsolete here. This design is by Horticulturist Anne Wildebor.

This container by Anne Wildebor has a mix of harmonious foliage plants with just a splash of contrasting pink flowers. The dramatic foliage is Canna 'Sunburst' on either side with a Black Elephant Ear (Colocasia) in the center. Coleus 'Fishnet Stockings' and Alternanthera 'Red Thread' are fillers all being set off by the pink angelonia in bloom. Again the low crisp container would be muddied up by a spiller.

This container by Anne Wildebor is about texture and the wonderful color we take for granted: GREEN. A spectacular 'Macho' Boston fern is perfectly punctuated by a white Caladium. This container only gets morning sun under the east overhangs of the Visitor Center.

This dramatic Leopard-Palm (Amorphaphallus konjac) has a pink caladium to help set off the subtle pink in the print of its stem. A spiller would "muck up" the elegant container. This design is by Anne Wildebor.

Even Edible Landscaping can be unique: this container near the entrance to the Heartland Harvest Garden has a dramatic fig (Ficus carica) with a base of curly parsley for contrast. It's all green but the drastic change between coarse dramatic leaves of the fig and fine detail of the parsley leaves make it work. This design is by Matt Bunch and Barbara Fetchenhier: look for their containers of edibles at the entrance plaza to the Heartland Harvest Garden north of the Visitor Center.

The seasonal display beds around the Visitor Center are reaching maturity with this wonderful planting (designed by Tracy Flowers - now gardener at the Kauffman Memorial Garden) outside the north side of the Conservatory: huge Castor Beans, sword-like Purple Majesty Millet, purple and white Kahuna Petunias and an edging of trailing Blackie Sweet Potato all make for a stunning, tropical-esque composition.

The Year of the Lily at Powell Gardens

The ample moisture and more reasonable temperatures have made the summer of 2008 the year of the lily at Powell Gardens. Lilies (Lilium spp.) are bulbs, most with exceptionally showy flowers and some with intense fragrance.

There are hundreds of species of lilies and the Easter Lily (Lilium longiflorum) is one of the most popular. Easter lilies are actually from Asia but forced into bloom for Easter sales. Hardy selections of Easter Lily bloom in midsummer and are pristine white with a very fine aroma. These were photographed in the Perennial Garden. The Madonna Lily (Lilium candidum) is the actual lily that is the symbol of purity and faith for Christians. Madonna lilies must be ordered now and planted by Labor Day because they must grow some foliage before fall.


There are thousands of cultivars of lilies but luckily they are assigned into several groups: Asiatic Lilies are some of the easiest to grow in our climate and come in a wide array of colors from white to yellow, orange, red and burgundy: this is the cultivar 'Savannah' in the Perennial Garden. Most Asiatic lilies are scentless and the flowers face upwards.


Tumpet lilies like this cultivar 'Golden Splendor' on the Island Garden are tall with trumpet shaped blooms that are also fragrant. This clump was hit hard by the Easter freeze of 2007. It languished all last year but we "let it be." This year it came back as if nothing had happened and seemed to make up for lost time!


Oriental Lilies are some of our most fragrant and require proper siting in our climate. These Stargazer Oriental Lilies were photographed in the Perennial Garden--in the afternoon shade of native trees. Oriental Lilies can literally bake in our hot afternoon sun so that the flower buds brown and never open.

New hybrid lilies have created quite a splash. This is a LA Lily: LA stands for longiflorum (Easter) - Asiatic (not Los Angeles!). LA lilies have the colors of Asiatic lilies, the fragrance of Easter lilies, and an exceptional hybrid vigor. This is the cultivar 'Gerrit Zalm' in the Perennial Garden which would be a great addition to a moon or white garden.

Some of the newest hybrid lilies show incredible vigor! This is a new Orienpet lily. Orienpet stands for Oriental - Trumpet hybrid lilies. These have the most hybrid vigor, good heat resistance and awesome fragrance. The unnamed hybrid shown from the Perennial Garden is well over 6 feet tall. Unfortunately the colors of many Orienpet lilies are just plain ugly blends of pink and yellow.

Powell Gardens' favorite Orienpet lily is the cultivar 'Silk Road,' which graces the entrance to the Island Garden's Sunken Garden. It has good color, fragrance and abundant bloom on sturdy 6 foot stems! Make sure to include lilies into your gardens for next year--there are many species and even more cultivars to choose from. Many of the later blooming varieties are still in bloom for ideas at Powell Gardens.

Mimosa, Exotic Beauty or Garden Pest?

Mimosa trees (Albizzia julibrissin var. rosea) are currently in full bloom at Powell Gardens and throughout Greater Kansas City. When I first moved to the area 12 years ago, I was surprised to see so many of them growing here (I thought they would not be hardy here). I was also bombarded by gardeners commenting that they either love them or hate them! Now that I have been here and observed the trees through 12 seasons I feel like I can weigh in on them: The successful trees in the area are of the variety rosea which noted plant explorer E. H. Wilson brought back from Korea to the Arnold Arboretum. These trees are more refined and hardy (to -15F or more) than the typical species "monster" you see escaped along the roadsides in the South. Mimosas are a long blooming tree, at a season when their bright color adds to our tropical-like weather. The fragrant flowers are nectar-rich and attract a plethora of beneficial insects (including butterflies) and hummingbirds. The trees have a horizontal form that seems to fit in our prairie landscapes even though they originated in Asia. The ferny foliage is delightful and airy; folding up each night to give the tree a whole new look.

The negatives are that past severe winters clipped many of them to the ground. It is no fun removing such a large plant! Virtually all of them recovered with stump sprouts. Some local trees amazingly survived the big freezes of the 1980's and many are over 50 years old according to their owners. The seeds of mimosa are prolific and germinate with abandon in disturbed soils in the garden landscape. Fortunately they do not germinate into undisturbed soils or wildlands so I would not consider it invasive like it is in southmost Missouri and points south. It is a nuisance to pull up all the seedlings as weeds in the garden!

Mimosa in mid-day, over 90F heat north of the Visitor Center (the flower color does bleach out to pink in extreme heat).

Powell Gardens Mimosas are grown from local hardy trees or regional sources. I would advise anyone wanting this tree to do the same: local seedlings "Brian's Choice" are available at Greeson's or trees wholesale grown by Forrest Keeling Nursery sold at Colonial Nursery are good bets. The beautiful purple-leaved variety 'Summer Chocolate' is a beautiful plant but was killed to the ground out here by 2007's Easter Freeze. It came back and did not dieback last year. We look forward to how it will perform over the years at is always a plant that attracts attention. I will leave it up to you whether you want a mimosa in your landscape -- good or bad, the choice is yours! You can always come out and experience them at Powell Gardens: most north of Visitor Center surrounding the Dwarf Conifer, Butterfly and Fountain Gardens. Three seed grown trees from an old (now removed) tree in Brookside we call "KC Red" can be seen at the Rock & Waterfall's trolley stop. This strain grows with shocking sturdiness and vigor but is still of the hardy rosea variety. We usually grow some of these trees for our spring plant sale.