Penstemons — Tough and Beautiful Natives

Featured

 

by Diane Engles, HAS Trustee

 

If you are looking to plant more water-wise and pollinator-friendly perennials this spring, a top contender is the penstemon. This North American native plant produces colorful tubular flared blooms on vertical flower spikes — perfect feeding stations for hummingbirds and other pollinators. The shape and color of the leaves vary depending on the cultivar. They can be oval, lance-shaped or needlelike with colors ranging from green or blue-green to deep purple. Penstemons are related to foxgloves and snapdragons as is evidenced by the similarity of their blossoms. There are over 250 species of penstemons native to the U.S. and over 800 cultivars and hybrids.

Cardinal penstemon (Penstemon cardinalis) showing the “beards”
Photo Credit:  High Country Gardens

“Penstemon” is derived from the Greek words penta and stemon, referring to the flower’s five stamens, four of which are fertile and one sterile. They are also known as beardtongues due to the pollen-free stamen (or staminode) which protrudes from the flower and is covered by small hairs.Penstemons are long blooming and do well in a drier climate such as ours. They are especially happy in loose gravelly soil with good drainage. Penstemons tend to bloom in early summer just after the spring bloomers have faded. They come in sizes ranging from dwarfs that tuck nicely into rock gardens, to waist-high plants that can bring color and movement to the back of the border. They have a broad palette of colors ranging from soft pinks, lavenders and yellows, through more intense shades of violet, rose, and orange, as well as being known for electrifying reds and blues. Deadheading can result in a second flush of bloom, but leave one or two stems to set seed as penstemons are short-lived compared to other perennials.

Pineleaf Penstemon (P. pinifolius) comes in orange and yellow and is one of the shorter penstemons. The older variety is a vivid orange-red, and there is a yellow variety called “Mersea Yellow”. Pineleaf Penstemons have green needle-like foliage with loose spires of blossoms reaching about 10-12 inches in height. Plant Select® has introduced a variety called SteppeSuns™ Sunset Glow.  Plant Select® describes it as: “This selection is more than 20 years in the making with each clone and generation an improvement in color and plant size. SteppeSuns™ Sunset Glow is a warming orange color that blooms for a very long season.”

    

 

 

 

Left to right: Orange, yellow, and Sunset Glow Pineleaf Penstemons
Photo Credits:  High Country GardensHigh Country Gardens, Plant Select
®

 

Photo Credit: JerryFriedman
/ CC BY-SA (http://creativecommons.org/licenses/by-sa/3.0/)

Rocky Mountain Penstemon (Penstemon strictus ) is hardy to Zone 4. Native to Wyoming, Utah and western Colorado, it thrives in rocky or gravelly soil but will adapt to others. One of the longer-lived varieties, it has a basal mat of rounded green foliage with bright blue blooms rising 2-3 feet tall. I first saw it growing in the wild and was delighted to find it will adapt to life in a garden.
 

 

Photo Credit:  High Country Gardens

 

Palmer’s Penstemon (Penstemon palmeri)  is a tall penstemon hardy to Zone 5. One of the few fragrant penstemons, It has gray green foliage topped in early summer by honey-scented light pink flowers on spikes 4-5 feet tall. Native to southern California, Arizona and Utah, it thrives in arid climates and dry, sandy or gravelly soils. It will not tolerate clay.   

 

Photo Credit:  Plant Select®

Carolyn’s Hope Penstemon (Penstemon x Mexicali) is a lovely pink and hardy to Zone 4. It is a Plant Select® variety, a hybrid between Mexican and American wild penstemons. Carolyn’s Hope was developed in Colorado for the purpose of raising funds to support breast cancer research at the University of Colorado Cancer Center. It is of medium height, 14-18 inches tall and 12-15 inches wide. Cheerful pink, white-throated tubular flowers and dark pink buds rise above narrow, glossy green foliage and are attractive nearly all summer long. Deadhead in order to prolong bloom. Seedlings are often not true to variety color, so pull (if desired). 

 

Photo Credit:  Plant Select®

Penstemon Pikes Peak Purple® (Penstemon- Penstemon x mexicali ‘P007S’ ) is another mexicali hybrid with violet-purple flowers all summer, hardy to Zone 4. It has narrow dark green leaves that form an attractive mound of medium height 14-18 inches tall and 12-14 inches wide. It thrives in a range of soils and will take some shade. I grew Pikes Peak Purple® last year and loved its intense coloration. It looks lovely with yellow flowers as companions.

 

 

Blue Mist Penstemon (Penstemon virens ) in the author’s garden

We’ve barely dipped our toes into the wide variety of penstemons that are readily available. You will find these and many others at your local garden centers.

 

If you want to dive deeper into the world of penstemons, you can check out the American Penstemon Society.  This organization was founded in 1946 and continues their mission of studying, hybridizing and exchanging seed among members today.

 

It’s Lavender’s Year!

(Published originally in the March 2020 HAS News and Announcements)

by Diane Engles, HAS Trustee

Photo Credit: National Garden Bureau

 

The National Garden Bureau has declared 2020 to be the “Year of the Lavender.”  Lavender is a deserving plant in any year! With outstanding intense fragrance, silvery foliage and xeric qualities, it is a multi-talented addition to any garden.

Cultivated for centuries, this drought-tolerant member of the mint (Lamiaceae) family has 47 species. It has a wide range of native habitats, ranging from Cape Verde and the Canary Islands, across Europe to northern and eastern Africa, the Mediterranean, and from southwest Asia to southeast India.

In addition to lavender’s floral show, essential oil can be extracted from the blossoms, and dried lavender is used in sachets and potpourris. Lavender is also used as a culinary herb. The blend “Herbes de Provence” is used in soups and roasts; lavender also finds its way into desserts such as lavender shortbread and lavender ice cream.

Most lavenders are actually subshrubs and will develop woody stems over time. They are deer- and rabbit-resistant — many gardeners with deer problems interplant them among plants they wish to protect. While they resist deer and rabbits, pollinators including hummingbirds and native bees find them hard to resist.

Lavender thrives in full sun, heat, and fast-draining, low-fertility soils. Lavenders do not like saturated roots, so avoid planting them in compost-enriched, water-retentive soils. If you have clay soil, amending with inorganic mulches, such as gravel or sand will help. All lavender types need little or no additional fertilizer, and after establishment are xeric. However, during their first growing season in the ground, they need regular irrigation several times per week to establish themselves. Once established, water much less frequently, but deep watering is their preference. In spring, wait until new growth starts to prune. Pruning too early can kill the plant.

Lavender can be grown in containers. Terra cotta pots are good choices since they tend to keep soil on the dry side. Use a soil that provides sharp drainage. You can over-winter lavenders that aren’t hardy in our area. Bring plants indoors before frost arrives and store them through winter in a cool room near a bright window or in a cool basement with grow lights, watering just enough to keep plants alive. Move plants outside in spring when all danger of frost has passed.

The most common types of lavender which are hardy in our area are English lavender (Lavandula angustifolia) and lavender x intermedia (Lavandula x intermedia) which is a hybrid cross between English Lavender (L. angustifolia) and Portuguese lavender (L. latifolia). Spanish (L. stoechas) and/or French lavender (L. dentata) are only hardy to Zones 7 and 8, but may be container grown in our area.

One of the oldest English Lavenders, Munstead (L. angustfolia ‘Munstead’), was introduced in 1916 by the English garden designer Gertrude Jekyll. It is hardy to Zone 5. Newer cultivars Hidcote Blue and SuperBlue, are hardy to Zone 4. There are over 40 cultivars of English lavender with colors ranging from violet to pink to white. Sizes range from compact at 10-24 inches tall and wide to 2-3 feet tall and wide, so there is an English lavender for every garden! English lavender blooms from late spring into summer. Deadhead or harvest flowers to promote continued bloom.

Photo Credit:  National Garden Bureau

Munstead (L. Angustifolia ‘Munstead’) is one the hardiest and easiest to grow varieties of English Lavender. Hardy to Zone 5, its large blooms mature to a bold, deep blue-purple color. It is a smaller lavender growing 12-16 inches tall and 24 inches wide. It grows well in containers and works great in hedges or knot gardens.

Photo Credit: National Garden Bureau

Hidcote Blue Lavender (L. angustifolia ‘Hidcote Blue’) has deeply colored violet-blue flowers and a compact uniform habit. It is an excellent choice for edging walks and paths, where the aromatic flowers and foliage can be easily enjoyed. It is also a good variety for drying, as it holds its color well. One of the most cold-hardy lavenders, Hidcote Blue is hardy to Zone 4.

Photo Credit:  Plant Select

Wee One (L. angustifolia ‘Wee One’)  is a Plant Select variety, introduced in 2017, hardy to Zone 5. It is a dwarf English lavender with compact heads of lavender-blue flowers and dark blue calyxes. In flower, the mature plant is only about 10″ in height. Slow growing and very xeric, Wee One has excellent heat tolerance as well as  cold hardiness. It is a great addition to a rock garden or small spaces.

The intermedia hybrids (Lavendula x intermedia)  are also known as lavandin. These hybrids extend the blooming season as they flower later than English lavenders. They typically begin blooming in July or August and end in late summer. Two well known and proven varieties are Provence and Phenomenal. They are taller than most English lavenders reaching up to 3 ft x 3 ft.

Photo Credit:  High Country Gardens

The cultivar Provence (Lavandula x intermedia ‘Provence’ is hardy to Zone 5. Its foliage is silvery green and its blossoms of lavender-blue can reach up to 3 inches long.  It also boasts one of the strongest fragrances of the lavenders.  It reaches 12-18 inches tall by 24-36 inches wide in colder zones. In warmer climates it can reach 3ft x 3ft.

Photo Credit:  National Garden Bureau

Phenomenal lavender is a newer cultivar with violet flowers. It is known for its cold hardiness and tolerance to heat and high humidity and is hardy to Zone 5. The plants grow into a mounded shape, with purple flowers on tall stems in mid-summer. It is a tall plant,  growing 30-32 inches tall and 30-36 inches wide.

Spanish lavender (L. stoechas) is only hardy to Zone 7. You may see it offered at local garden centers, so be aware that we must grow it in containers here and winter it over, or use it as an annual. With its perky “rabbit ear” blooms, it makes a great focal point in a container where the fragrant leaves and flowers can be enjoyed close up. Spanish lavender grows 14-16 inches tall and 15-18 inches wide.

French lavender (L. dentata) is not the same as Spanish Lavender (L. stoechas) although the names are often used interchangeably. French lavender is known as fringed lavender due to its serrated leaves. This lavender forms a bushy shrub of grey-green leaves that is easily pruned and thus one of the best types for forming into topiary shapes.

The flower heads on French and Spanish lavender aren’t useful as a culinary lavender because the flavor has heavy camphor or piney tones. The blooms do make nice lavender wands and potpourris. Harvest flowers for drying before any of the blossoms start to turn brown.

Photo Credits:  National Garden Bureau

Above are Spanish lavender Bandera Purple in a container and a closeup of Spanish Lavender Double Anouk.

We plan to have eight lavenders at our HAS Gigantic Plant Sale this year.  We’ve ordered English  lavenders Wee One, Munstead, Hidcote, Hidcote Blue and Twickle Purple.  We have selected three well known and proven lavender intermedia hybrids: Grosso, Provence, and Phenomenal. We’re excited about lavender in 2020 — come find one or more for your garden!

In the HAS Gardens: Evergreens

Article by Diane Brunjes, HAS Gardener, published in February 2020 HAS Announcements


Photo by Diane Engles

Living in a northern climate as we do, makes one appreciate anything that brings color and life to the garden in the winter. And there seems to be nothing that does that better than conifers. Strictly speaking, the ones we are referring to are evergreens. There are however, conifers that are NOT evergreens, like larches (Larix), the bald-cypress (Taxodium) and the dawn redwood (Metasequoia), which all lose their needles for the winter. But the ones we will focus on now are the ones that retain their needles over the winter – hence, ever-green.
Many gardening experts and designers say that your garden should be composed of approximately 30% evergreens. This figure can be adjusted to suit your tastes, but how many of us can claim that we get anywhere near that percentage? But considering that most of the garden is D-O-N-E by late October, and really doesn’t get going again until April, that leaves at least five full months of drab – unless you plan and plant carefully.
Of course, many perennials bring winter interest, like sedums, opuntias, grasses, agaves, penstemons with its evergreen foliage, hellebores, coneflower seedheads, and artemisias are just a few of the flowering herbaceous plants that we can rely on for winter interest. At least, until that two-foot snowstorm with 40 mile-an-hour winds occurs, and then most of our interest is plowed under until the next growing season.
That’s why adding evergreens to your garden can be the year-round boost that you might be looking for without realizing it. One of the evergreens we will be adding to the sensory garden this year is Pinus nigra ‘Bambino’. The name alone is enough reason to grow it, but its dwarf nature and tight branching certainly are other reasons. Forming a low wide dome over many years, this evergreen eventually becomes so dense, that reaching in with a gloved hand every two or three years becomes necessary to clean out the accumulation of fallen needles. Although it looks very “pet-able”, the needles retain the stiffness of the Austrian pine, and if you do clean, do it carefully. Look for it in the HAS Gardens this spring.
Another evergreen we are excited to be adding is the very narrow exclamation point Juniperus scopulurum ‘Blue Arrow’. A selection of our native Rocky Mountain juniper, this is even narrower and slightly smaller than J. ‘Skyrocket’. Its new growth tends to be slightly bluer, but this varies per specimen, as we have seen some that definitely trend more towards green. We will be adding three of these in the Demo Garden. This kind of exclamation point has several design functions. In one spot it will “stop” the eye, in another, it will be simply a backdrop to other features, and in a third spot, it will be that exclamation mark that is so useful in the garden if not overused. In ten years, these junipers will be 12-15 ft tall x 2 ft wide.
If you are looking for design inspiration for your own garden, be sure to google The Bressingham Gardens in Norfolk, England. Some conifer gardens can feel heavy and even a bit oppressive, but Adrian Bloom makes amazing use of grasses, vibrant-stemmed dogwoods, and deciduous plants to bring lightness and movement to his garden. Be warned, though, if you watch the video on their website, you will think it is just a perennial garden! Bloom used to use, very heavily, heaths and heathers (which we can’t grow) but in the last decade has begun to move to the above-mentioned groupings. This has horrified some conifer garden purists, but makes a very welcome change, we believe, for everyone else.
Happy Gardening, and as always, come visit the Gardens!
                                                        

Photo of limber pine courtesy of Nebraska Forest Service

 P.S. If you would like to reserve one of these trees that will be offered at the Plant Sale, please click on the links provided below.

Reserve a Hung Hai Tung Crabapple

Reserve a Gila Monster Oak

New Plants from Plant Select for 2020

by Diane Engles, HAS Trustee, published in the January 2020 HAS Announcements

As we enter 2020, we are excited about new plant introductions that have been selected to grow well in our mountain climate zones. Plant Select®  has introduced seven new garden-worthy perennials this year. Plant Select®  is a nonprofit collaboration of Colorado State University, Denver Botanic Gardens and professional horticulturists whose mission is to find and distribute the very best plants for landscapes and gardens from the intermountain region to the high plains and beyond. I’ve listed below these new introductions in alphabetical order by Latin name, with a brief description.

Dwarf Leadplant (Amorpha nana),  hardy to Zone 3. This cultivar of a small native shrub sports ferny, bright green foliage and is decorative when not in bloom. In June it produces purple spikes with a sweet honey-like fragrance. As a bonus, it doesn’t require pruning to look good. The common name of lead plant refers to the once-held belief that the plant was an indicator of the presence of lead in the ground. It is a pollinator magnet, attracting  bees, butterflies, moths, beetles and other beneficial insects.

Because it is a legume, lead plant can fix nitrogen with the help of a symbiotic soil-dwelling microbe and create its own fertilizer. This advantage keeps it looking green and healthy in poor soils. Once established it takes care of itself in the landscape, requiring little water. Leadplant looks great in mixed xeric plantings with Dwarf Blue Rabbitbrush ( var. nauseoChrysothamnus var. nauseosussus), Butterfly Plant (Asclepias tuberosa), Blanketflower (Gaillardia aristata), and grasses.

Next on the list, with a lovely name is Mongolian Snowflakes (Clematis hexapetala), hardy to Zone 5.  Mongolian Snowflakes is not a vining clematis; it forms a mound of foliage about 18 inches tall and up to three feet wide. Its bloom season is from May through the summer creating a mounded snowstorm of 2-inch ivory-colored flowers. This clematis has multi-season interest since the spent flowers give way to shiny, feathery seed puffs that are showy in their own right. Mongolian Snowflakes will adapt to low-water conditions and can be xeric once established. It will also take partial shade as well as full sun. Use it in xeric plantings and rock gardens as well as mixed perennial borders.

 

Golden Candles (Thermopsis lupinoides), hardy to Zone 3. One of the earliest blooming perennials, Golden Candles is a welcome sight after our long winters. Thick clusters of bright yellow buds emerge and open into golden spires. It will keep blooming into June. Lupine-like foliage persists nicely the rest of the summer adding texture to the garden. Golden Candles can reach two to three feet tall and 20-30 inches in width. It is another garden-worthy member of the pea/bean family from Asia, that adapts well to our climate.

 

Indigo Blue Dragonhead (Dracocephalum ruyschiana),hardy to Zone 3. This new Plant Select® introduction is easily grown, maturing to a tidy mound 12-16 inches x 10-12 inches. Its needle-like leaves become decorated with fragrant dark blue flowers in early summer. Dragonhead refers to the flower shape which resembles a snapdragon. Indigo Blue Dragonhead will thrive in a dry meadow or rock garden setting and is tolerant of a wide range of soil types. It can tolerate some shade; water needs are low to moderate.

 

 

Leprechaun Southernwood (Artemisia abrotanum ‘Leprechaun’),hardy to Zone 4. This compact artemisia forms a dense, symmetrical mound of aromatic, whorled silver-green foliage.  Leprechaun will grow in in full sun, part shade, or full shade! It prefers loam or sandy soil. It brings a soft texture to borders and rock gardens. An interesting use recommended by Plant Select® is to plant it as a hedge resembling boxwood in xeric locations.

 

 

And finally for this year, green and silver forms of Lamb’s Ears (Stachys lavandulifolia), hardy to Zone 5. Lamb’s Ear is a wildflower from Turkey. Both cultivars will take some shade, and prefer loam or sandy soil. Their water needs are low to moderate and they are deer- and rabbit-resistant.

Pink Cotton Lamb’s Ear (Stachys lavandulifolia – Green Form). This cultivar makes low mats 8-10 inches tall and 12-18 inches wide. Foliage is green, soft, and attractive. In late spring to early summer,  flossy clusters of pink trumpets appear which are suggestive of pink cotton candy.

 

 

Summer Frost Pink Candy (Stachys lavandulifolia ‘P020S’ – Silver Form) . An elegant, silver sport of Pink Cotton Lamb’s Ear grown primarily for its silver-haired leaves — this selection blooms slightly less vigorously than its parent, Pink Cotton Lamb’s Ear, and is primarily valued for its foliage which bring color and texture to a border or rock garden.

 

 

We will try to order all these plants for our Gigantic Plant Sale (May 15-17) depending upon their availability. Watch this newsletter for the plant sale Master List later this spring to check for any of these great plants that catch your interest!

Photo Credits:  All photos from Plant Select, except Mongolian Snowflakes which is from Juniper Level Botanic Gardens

Schedule your gift to Colorado Gives Day

Amazingly, 2019 is nearly over! We hope you’ll make 2020 another successful year for the HAS gardens by contributing through Colorado Gives Day.

You can schedule your donation online now through December 9 to take place on Colorado Gives Day, December 10. Colorado Gives makes it very easy to donate to Horticultural Art Society and 2,500 other non-profits in Colorado.

You can also give throughout the year or make a recurring donation. View our profile with this link or go directly to our Colorado Gives donation page with the button below.

HAS receives no funding from governmental sources.