Not-So-Sweet Smells of Fall

Fall is a wonderful time to be the Arboretum grounds keeper – watering duties slow down, weeds are relenting, and I can wear my favorite sweaters to work. Brisk mornings and the coppery hue of the landscape make for a pleasant work week.

But wait … what’s that smell?

Working in many different areas of the Arboretum has led me to discover some autumnal aromas that are downright unpleasant. It isn’t the cinnamony smell of pumpkin spice latte on the wind, but a stench of skunk and old cheese! Early fall moisture and warm days bring out the worst of smells in some of our flowers and shrubs, causing me to cringe when working near the fetid few.

If you have visited us recently, perhaps you too are wondering about the foul air. Wonder no more! I introduce to you the top three smelly plants at the Arboretum:

1. Cypress (Cupressus arizonica)

While cypress trees traditionally have a pleasing aroma, this variety emits an odor redolent of skunk. The icy blue foliage may be off putting at first sniff, but if you rub the needles between your fingers the scent becomes influenced by citrus and spice, making it somewhat less offensive and almost forgivable. Almost.

(Left) Arizona Cypress tree in the Northwest corner of the Arboretum. (Right) Cypress foliage

(Left) Arizona Cypress tree in the Northwest corner of the Arboretum. (Right) Cypress foliage

Many evergreens have strong scents, and they get their classic “Christmas” smell from gummy resins, which contain high concentrations of terpene alcohols and acids. Unfortunately, this tree smells less like Christmas and more like roadkill.

 

Penstemon digitalis seed pods near Dyck Arboretum Visitor's Center

Penstemon digitalis seed pods

2. Penstemon (Penstemon digitalis)

Penstemon is a showy spring bloomer that produces reddish, tear-drop shaped seed heads. But when you decide to cut those seed heads down for clean up or collection, I suggest pinching your nose! The bloom doesn’t have a strong scent, but the smell of the seeds and pods has been likened to animal vomit, or very acidic urine. The seeds themselves, though tiny, seem to make the biggest stink – after handling seed, it takes many rounds of hand washing to remove the tangy, kitty-litter smell from your fingers.

 

3. Rough-leaved dogwood (Cornus drummondii)

Dogwoods grow in dense thickets and are a popular choice for creating natural borders. Because of their thick cover, they are attractive to wildlife and nesting birds. But they are not attractive to the human nose. Dogwood leaves smell ever so slightly of curdled milk. In calm, humid weather, walking near our dogwood plantings can feel as if you have a dirty gym bag on your face. Luckily, as cooler weather sets in, the foul air around these plants seems to dissipate.

So, why the big stink? For flowering species, exuding sweet smells is a signal to bees and butterflies that nectar is ready. No two floral scents are alike in molecular makeup, allowing for specific pollinator attraction. Most plants that give off an unpleasant balm are attracting a less charismatic type of pollinator – flies and beetles. If not for pollination purposes, a malodorous plant may be using its sour perfume as protection from herbivores such as rabbits and deer.

Whatever the reason, I won’t hold the smell against them…but I may choose to avoid pruning them for as long as I can get away with it!

 

Favorite Penstemons for the Landscape

Penstemons are beautiful spring blooming wildflowers that provide incredible color and attractive forms.

I have been convinced through trial and error that some plants are more garden worthy than others.  If matched with the proper sunlight and soil, penstemons fit that category.  Whether planted in the spring or fall, all of the penstemons will bloom the next year.  Right now our penstemons are putting on a show.  They have spectacular tubular flowers of white, pink, red or lavender, depending on the species and varieties.  Here are some of my favorites for three different garden types.

 

For a more formal prairie garden…

Shell-leaf Penstemon (Penstemon grandiflorus) – Found in prairies throughout the Great Plains, it has thick burgundy stems, waxy blue-green leaves and large lavender flowers. Plant in full sun in any soil that stays medium to dry throughout the year. Grows up to 3’ tall.

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‘War Axe’ is an exceptional strain of Shell-leaf Penstemon.  Seeds collected from plants with maroon, red, purple, and pink blooms are mixed together and planted.  The resulting plants will have one of these colors and each plant is different.  What a surprise in the spring!  Same form and cultural requirements as the species.

Smooth Penstemon (Penstemon digitalis) – I love this penstemon as a perennial border.  The white flowers in spring have just a blush of pink and develop interesting seed heads.   It adds outstanding form and texture to any landscape throughout the year.  Penstemon ‘Dark Towers’ is a beautiful selection of smooth penstemon with attractive reddish-purple foliage and soft pink tubular blooms.

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Photo courtesy Walters Gardens

Tube Penstemon (Penstemon tubaeflorus) -The snow-white flowers shine in the spring garden.  The morning dew covers the tubular blooms in the morning.  Each stem reaches for the sky, ultimately growing three feet tall.  Pollinators flock to the flowers, especially large bees that dangle from flowers as they try to crawl inside to reach the nectar at the back.  It is amazing to watch the different pollinators work these flowers.

Native companion plants for the formal prairie garden: Spiderwort (Tradescantia sp.), Evening Primrose (Oenothera macrocarpa), and Butterfly Milkweed (Asclepias tuberosa)

Penstemon tubaeflorus. Photo courtesy Craig Freeman

Penstemon tubaeflorus. Photo courtesy Craig Freeman

 

For a pond or stream edge…

Smooth Penstemon is an excellent choice.  It is very adaptable to wetter environments.  It has thrived next to our pond edge for years with no ill effects from flooding or too much moisture.

‘Husker Red’ is a selection of Smooth Penstemon with wonderful deep red foliage.  The white flowers are similar to the species with a blush of pink.  It thrives wherever you plant it.

Native companion plants for the pond edge: Gray-headed coneflower (Ratibida pinnata), Kansas Gayfeather (Liatris pycnostachya), Meadow Blazing Star (Liatris ligulistylis), or Rattlesnake Master (Eryngium yuccafolium)

 

For a rock garden…

Cobaea Penstemon (Penstemon cobaea) – Found regularly within the Flint Hills region on road cuts and exposed bluffs and hills, it has large white flowers with lavender lines inside the throat.  Plant in full sun in a medium to dry soil.  Grows to 24” tall.

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Rocky Mountain Penstemon (Penstemon strictus) – This penstemon is not native to our region, but is quite adaptable.  The foliage is clean and evergreen with the rosy-lavender blooms held on one side of the upright stems.  It grows to 24” in full sun and a lean, medium to dry soil.

Native Companion plants for rock gardens: Evening Primrose (Oenothera macrocarpa), Shortstem spiderwort (Tradescantia tharpii), Purple Poppy Mallow (Callirhoe involucrata), Narrow-leaf Coneflower (Echinacea angustifolia)

Establish these penstemons like any other perennial with daily watering for the first few weeks after planting and check them periodically through the year.  You will be rewarded by these resilient wildflowers.  They have spectacular flowers that you must experience.  Wow is all I can say.

 

 

Scott’s Top Ten Sun-Loving Plants for Spring 2015

One of the themes this spring for planting is diversity.  By planting a diversity of wildflowers and grasses in your garden, you will attract many different forms of wildlife, including pollinators and birds.  A wide variety of plants blooming at different times of the year will provide interest and beauty throughout the growing season.

As we have been busily getting ready for the plant sale this week, I can’t help but notice the diversity of plants available this spring.  There are so many wonderful plants to choose and incorporate into a landscape setting.

Here are my top sun-loving plants for the spring sale:

Asclepias_viridis

Green Antelopehorn (Asclepias viridis)

This is the 2015 Kansas Native Plant Society wildflower of the year.  It grows 18 to 24 inches tall with green flowers in May and June.  It loves full sun and thrives in dry prairies.  Monarchs use milkweeds as a host plants.  Grow this species or any other milkweeds to increase habitat for the perilous populations of monarchs.


Photo courtesy Walters Gardens.

Photo courtesy Walters Gardens.

Penstemon ‘Dark Towers’

It is beautiful in flower and foliage.  In early spring, the whitish-pink tubular flowers emerge.  Bees and even hummingbirds flock to these flowers to sip the sweet nectar.  Not only is it attractrive when blooming but the maroon-purple foliage adds interest the rest of the year.  A plant for the front of a border that is attractive at many different seasons of the year.


Blue Grama Blonde Ambition

Blue Grama, Boutleoua gracilis ‘Blonde Ambition’

I was blown away by this grass last summer.  It looked fantastic with the airy golden flowers all summer.  The horizontal eyelash-like flowers wave in the wind atop the fine blue-green foliage.  It grows effortlessly in any sunny site and just about any soil.  Great in mass plantings or along borders edges.  Quite the dramatic, unique grass.


Vernonia Iron Butterfly

Ironplant, Vernonia lettermanii ‘Iron Butterfly’

I have grown to appreciate the toughness of this wildflower.  This selection found in Arkansas has fine foliage like Amsonia hubrichtii but stays more compact.  The dark purple flowers cover the entire plant in late summer attracting pollinators by the herd.  It thrives in hot dry locations.  When other plants are wilting, it is performing like a champ.


Photo courtesy Walters Gardens.

Photo courtesy Walters Gardens.

Arkansas Bluestar, Amsonia hubrichtii

I have put this plant on my top ten list just about every year because it is a great plant.  Sky blue flowers in spring develop atop stems with narrow leaves that whorl the stem.  Each plant can grow about three feet tall and three feet wide.  The real show is in the fall as the entire plant turns a beautiful golden yellow.  Plant in mass or alone in the middle of the border.  A garden worthy plant that should be used more.


Photo courtesy Walters Gardens.

Photo courtesy Walters Gardens.

Little Bluestem Schizachyrium scoparium ‘Twilight Zone’

This is a new and improved form of native Little Bluestem.  It colors up beautifully in the early fall but the iridescent silver-mauve foliage from spring to fall is eye-catching. Growing stiffly upright, this grass reaches three to four feet tall by the end of summer.  Plant as a backdrop for other perennials because the foliage is a wonderful complement.  Great native grass for interesting foliage and form.


Photo courtesy Terra Nova Nursery.

Photo courtesy Terra Nova Nursery.

Agastache ‘Raspberry Summer’

What an awesome perennial!  The large, dark raspberry pink blooms cover this plant all summer and into fall.  Pollinators flock to the blooms and make the plant come alive with activity.  Plant in full sun and well-drained soil.


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Yellow Purple Coneflower Echinacea paradoxa

A yellow purple coneflower is a paradox.  However, it is tough and beautiful.  The flowers emerge in May and June with long yellow ray petals.  It grows best in full sun, ultimately reaching 3-4 feet tall.  Mix with native grasses like Little Bluestem or Switchgrass to showcase the attractive seedheads later in the year.


Solidago ‘Little Lemon’               Photo courtesy of North Creek Nurseries 

Solidago “Little Lemon’

Goldenrods get a bad rap for causing allergies.  Actually, they don’t cause your allergies in the fall – that is the fault of the ragweed pollen instead.  So now that you know that tid-bit of information, you can plant this dwarf goldenrod in your garden.  It grows to 12 inches tall and mixes well with short grasses along a border or edge.  Plant in full sun for best results.


Photo courtesy Walters Gardens.

Photo courtesy Walters Gardens.

Beebalm Monarda ‘Cherry Pops’

Brilliant cherry-red flowers cover this new bee balm in midsummer.  The well-branched plants have clean mildew-resistant foliage creating a compact mound.  Each nectar sweet flower attracts hosts of pollinators throughout the summer.  Great new form for the front of a border or along a sidewalk.


It is time to get these plants in the ground.  The beneficial rains of the past few weeks have really got me itching to plant some of these varieties this spring.  There are so many beautiful plants that are worth trying.  Hopefully, you will have a chance to stop by the plant sale, take a look and give some of them a try in your own garden.