The Best Underutilized Plants 

Acanthus hungaricus

As a garden designer and nurserywoman, I am always scouting for uncommon plants that have a long season of interest and are not fussy about care. And when I say “long season of interest”, I mean plants which have a bloom period of 6 weeks or more, or have outstanding foliage for much of the growing season. If these plants are deer resistant and attract pollinators and butterflies, they score even higher.

I offer these exceptional underutilized plants for your consideration.

Acanthus hungaricus  Bear’s Breeches. Hardier for me than the better known Acanthus mollis, this selection has thrived near our stone wall in hot full sun and well drained soil (that’s your tip!) for 20 years. In early summer, stunning 3’ spires of two toned white and lavender flowers erupt and carry a show into August. Its big and bold dark green foliage is thought to be the inspiration for the design on Corinthian columns. Plants spread where happy, and I have found the foliage is a perfect foil for dying bulb foliage. Zones 6-9.

Calamintha nepeta

Calamintha nepeta ssp nepeta  Calamint. This remarkable long blooming sun loving shrubby mint is one of my all-time favorite perennials, yet it is still not widely grown. Plants form tidy mounds (read: do not run!) of rounded mint scented foliage in the spring, and begin to send forth many stems bearing tiny white flowers from mid July through September here in New England. C. nepeta ssp nepeta has faithfully performed for us for over 20 years, regardless of whether summer weather is hot, dry, cool or moist. We have never had this selection self-sow in our garden. If you are fluent in Greek, you might note that its generic name translates to beautiful mint.  Zones 5-7.

Kalimeris incisa ‘Blue Star’

Kalimeris incisa ‘Blue Star’  As much as I am wowed by voluptuous blossoms, I like to champion the strong garden performers which have quieter charm. One plant whose charm seldom disappoints is an Asian Aster relative called Kalimeris incisa ‘Blue Star’. This little number grows 15-18″ tall and 18-24″ wide, and begins its production of 1 1/2″ lavender blue daisies in June, carrying on into autumn (I kid you not.) ‘Blue Star’ forms tidy clumps; it does not run, unlike some of its relatives. Grow in full sun in zones 5-9.

Ruta g. ‘Jackman’s Blue’

Ruta graveolens ‘Jackman’s Blue’  A desirable and durable Rue, once relegated to the herb garden, but deserving a more prominent spot in the landscape.  ‘Jackman’s  Blue’ has a tidy growth habit with the prettiest aromatic blue gray pinnate foliage providing a decidedly  lacy effect. In late summer citron yellow flowers appear on stems just above the foliage which attract a myriad of butterflies and pollinators. Interestingly, I see ‘Jackman’s Blue’  featured  regularly in British garden periodicals. With a hardiness arrange of USDA zones 4-9,  there’s no reason not to use this plant more prominently here in the states. Grow Rue in a sunny spot in well drained soil. Yes, it is deer resistant.

Athyrium otophorum

Athyrium otophorum There are so many great ferns! Here’s one you should know about. Eared Lady Fern impressed us so much last year, we are still gushing about it. Easy to grow in average to moist soil (provide supplemental watering in dry spells to encourage fresh new frond production), this Athyrium put on nice growth in one season and stood out for it’s limey green fronds with deeper wine markings . Plants grow 15-24″ tall and wide, and are hardy in zones 5-9.

Brunnera ‘Diane’s Gold’

Brunnera macrophylla ‘Diane’s Gold’  Siberian Bugloss. Yellow foliage plants are so valuable in the shade garden for their consistent golden glow. In the short time I’ve grown ‘Diane’s Gold’, I have been impressed how quickly she established  after planting and thrived in a dappled shade bed. Although her  floral display of sprays of tiny sky blue flowers is most effective in late April and May,  ‘Diane’s Gold’  was still sending out an occasional flowering stem in July and August.  Foliage clumps stay under 12” tall but can easily grow 18-24” wide. Zones 4-9.

Disporum flavens

Disporum flavens  So easy, so stunning, so under planted…the sight of Korean Fairy Bells in the early spring garden always makes me smile. Sturdy shoots which resemble Solomon’s Seal (Polygonatum) emerge in April and extend to 2’, with canary yellow pendant blossoms in small clusters at the stem tips.  Disporum spread slowly by rhizomes and it may take a few years to form impressive clumps, but are long lived and deer resistant. Grow in part shade. Zones 4-9.

Peucedanum ‘Daphnis’

Peucedanum ostruthium ‘Daphnis’  Greater Masterwort. Upon first glance you might think what a refined Goutweed this is, but upon additional study you might notice that the foliage is larger and has more substance, with an attractive creamy yellow to white  variegation.  Plants do spread by rhizomes, but I would not call this invasive.  In early summer, 15-20” stems bear white umbels resembling Queen Anne’s Lace. I always cut back the flowers as they fade, as this encourages new foliage growth.  Grow in part shade.  Zones 5-9.

Clematis ‘Paul Farges’

Clematis fargesii ‘Paul Farges’ . Most gardeners are drawn to the big flowered Clematis hybrids, which tend to sulk after planting until their roots are well anchored. I appreciate a Clematis that doesn’t need coddling and ‘Paul Farges’ never asks for a fuss.  1.5-2” white blooms resemble a larger form of Autumn Clematis, but bloom time is June-August.   Flowers are born on both new and old an old wood (Group 2 in the Clematis books), so if you want to control its vigor, cut plants back to 12” in the spring. If left unrestrained, ‘Paul Farges’ will easily extend 15-20’. Use him over stone walls, fences, or to cover a pergola as well as scramble up a medium size shrub or small tree. ‘Paul Farges’ is hardy in zones 5-9 and is deer resistant.

Eleutherococcus sieboldianus vareigatus

Eleutherococcus sieboldianus ‘Variegatus’ (aka Acanthopanax sieboldiana variegata) Five Leaf Aralia.  As a nurserywoman, I always cringe a little when  plant names change…new gardeners become confused and long time gardeners have trouble finding  the plant listed under its old name. (And may I complain about genus names with more than 5 syllables?)

If you can get past the pronunciation, you will discover that this is one tough shrub for almost any situation with average to dry soil:  sun, partial or deep shade.  Eleuthorococus sieboldianus ‘Variegatus’  has quite showy  white edged palmate leaves on arching branches which can really illuminate a shady corner. Flowers  are produced in spring but they are inconspicuous. Take note that it does have thorns, which help to deter unwelcome creatures, like deer.  Plants can grow 6-8’ tall and wide rather quickly.

Clethra barbinervis

Clethra barbinervis  Japanese Clethra is waiting to be discovered. Yes, our native Clethra alnifolia, also known as Summersweet, is a great plant but this Asian species has a few extras going for it.  C. barbinervis is a plant for all seasons, boasting fragrant mid summer blossoms, yellow-orange-bronze fall color, plus exfoliating bark in winter. If left unpruned, C. barbinervis will grow as a multistemmed shrub, but I prefer to see it trained as a small tree with single or 2-3 leaders, with lower limbs removed, so that the showy bark can be better appreciated.

Flowers form in July, bearing twisting 4-6” racemes of sweetly scented white flowers, which drip from the branches into mid August. It prefers a well-drained, neutral or slightly acidic soil with adequate moisture and can grow 15-20’ tall in zones 5-8. Clethra barbinervis grows well in dappled shade, although it will tolerate and bloom abundantly in full sun, if watering needs are met.

Are you growing any of these plants in your gardens?

17 thoughts on “The Best Underutilized Plants ”

  1. Hi Kath, Is Clethra alnifolia, also known as Pepper Bush? It’s loved by bees and adds a special flavor to their honey. Any comparison with Japanese Clethra ? Would having both in a yard ‘contaminate’ the either species?

  2. Yes, Clethra alnifolia is also known as Pepperbush, and yes I can attest that the honey flow in August when the Pepperbush is in bloom is the best of the season. The honey bees also love Cletha barbinervis!

  3. I love the tip about Jackman’s rue. I planted an ordinary rue plant last summer, and it did very well despite heat and drought conditions. However, in late summer I was startled to see a very brightly colored caterpillar eating the leaves. Many people can’t even touch rue without skin irritation, so how could anything eat it? Our voracious deer herd avoid it. Turning to the internet, I soon learned that the caterpillar is the larva of a Black Swallowtail Butterfly, which I am delighted to feed. The plant survived just fine, so I will now seek out Jackman’s for a more refined foliage plant in my perennial border.
    I would also like to mention the way the waxy foliage looks in the rain–I call it the crystal teardrop effect–an added bonus.

  4. One reason for underutilization of Rue is the photosensitization after exposure to the sap, as in pruning or contact from broken stems and/or leaves. Even aware of this, I was burned to the point of blisters (yes, literally!) by absentminded contact with cut stems.

  5. Darn, I didn’t notice Athyrium otophorum when I ordered. Is it too late to add it to my order?

    Also, speaking of Clethra Barbinervis, will you be carrying ‘Takeda Nishiki’ Variegated Japanese Clethra in the future?

  6. Greetings Katherine,
    I was so pleased to see that you were featuring the Acanthus…I love it. I just planted my first one last season & am most anxious to see how it comes back this year. I have been enamoured with Acanthus forever, love it’s large, grand leaves that curl & swoop, soooo graceful. I will look forward to whatever you offer in ways of caring for this fabulous plant. Crossing fingers that mine has survived our New England winter. Isn’t spring exciting ? Thank you.

  7. I’ve just moved to Santa Fe, after all my gardening experience was in Boston. I bought lots of plants from you over the years, so I’m still on your email list. Would any of the plants mentioned here work in my new garden? I know the soil is alkaline, and not as full of organic richness but can I amend it?

  8. Great article!

    With so many chores on the To-Do list, I can really appreciate low maintenance plants. Here’s one for your list: fava beans.

    I planted fava beans (Vicia faba) last fall in my San Jose, CA, heavy clay, as a winter cover crop for a construction strip next to a fence. I didn’t expect much, but what I am still getting is nothing short of amazing. The plants have grown quickly and most are now 4 feet tall and covered with blossoms that the bees love and bean pods that my husband and I enjoy very much.

    I have done absolutely nothing for these plants and yet they continue to thrive in less than ideal soil. They are frost resistant and the only problem I have had is that some of them need propping up as their bean crop gets too heavy.

    Thanks again for adding to my list of plants to try!

  9. If you deadhead Clethra alnifolia blossoms will it repeat blooming or should one only cut as they go by to clean up look of spentflowers near an entranceway mass planting ?
    You turned me onto Acanthus which behaved wonderfully in a garden that I battle deer & woodchucks! I wonder if there is a list of non preferred woodchuck plantings’?!

    Thank you
    Margo B.

  10. Karen, I love Santa Fe!
    I think you should experiment with a few Hellebores, with attention to watering during dry spells.
    Hellebores do like a slightly alkaline soil.

  11. Eleutherococcus siebodianus is an amazing plant. I have two in dense shade with lots of roots in the soil. They light up that area of the garden. They’ve survived drought, harsh winters, and being stepped on, and they still perform like champs and look great.

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