Perennials

Having been in business for 25 years on Nantucket, we have seen many trends in the islands’ landscape community come and go.  When I started at the nursery 14 years ago, there was a huge demand for ‘Knock Out’ series roses, for example – but today we only sell a modest number of shrub roses of any type.  When I was actively landscaping, many projects called for broad swaths of hydro-seeded, exotic, love grass but now (thankfully) landscape architects are using a wide variety of native grasses for those applications.  In fact, incorporation of native grasses, shrubs and perennial plants in the landscape is a massive trend that we don’t see slowing down.  Unfortunately, we’ve also seen an incredible increase in deer pressure across the island, which has spurred the movement toward planting only the most deer-resistant plants available.

We’ve seen that many of the native plants recommended for our climate are no longer deer-resistant at all.  For shrubs, we still recommend Myrica pensylvanica (Bayberry) and Baccharis halimifolia (Groundsel) as the backbone of a native planting plan.  Native grasses like Panicum virgatum (Switch Grass), Schizachyrium scoparium (Little Bluestem), Sporobolus heterolepsis (Prairie Dropseed) and Deschampsia sps. (Hair Grass) are a good choice as well.  Recently, I’ve been impressed with the various species of Pycnanthemum (Mountainmint) for good deer and rabbit resistance.

There are several species of Pycnanthemum in the trade that can be planted in a variety of conditions.  All are native to North America, and attract a wide variety of pollinators.  They look great mixed with other native plants and grasses in meadow gardens but are also a great addition to butterfly gardens and traditional perennial borders.  These herbaceous perennials are members of the mint family, with fragrant foliage and varying degrees of hairy leaves and stems.  They are generally 3-4′ tall and flower in shades of white and pale lavender in high summer to early fall.  Mountainmint grows in spreading clumps that are enlarged by runners; when they are happy, they can spread quickly, but the edges of the clumps can be easily managed by spading and pulling up the runners once or twice a year.

Some of the most commonly available species are listed below:

Pycnanthemum curvipes (Stone Mountainmint):  2-3′ tall.  Ovate silvery/green leaves with purple-spotted white flowers.  Native to rocky outcrops, bluffs, dry hillsides, open rocky woodlands and fields of the South Eastern United States.

 

 

 

 

Pycnanthemum flexuosum (Appalacian Mountainmint):  2-3′ tall.  Ovate green, hairless leaves with white/pale laender flowers.  Native to South Eastern United States where it occurs in a variety of conditions.

Pycnanthemum muticum:  2-4′ tall.  Ovate silver/green fuzzy leaves with pale lilac flowers and showy bracts.  Native to moist woods and meadows of the North Eastern United States.

 

 

 

 

 

Pycnanthemum tenuifolium (Narrowleaf Mountainmint):  3′ tall.  Narrow green, hairless leaves with clusters of tiny white flowers.  Native to a wide variety of conditions in the North Eastern United States.

 

 

 

 

 

Pycnanthemum verticillatum var. pilosum aka P. pilosum (Whorled Mountainmint):  1-3′ tall.  Grey/green leaves with clusters of white flowers.  Native to forests and meadows of a wide swath of the Eastern and Central United States.

 

 

 

 

Pycnanthemum virginianum (Virginia Mountainmint):  2-3′ tall.  Narrow lance-shaped leaves with white flowers dotted in lavender.  Native to moist woodlands and wetlands of Eastern United States.

There are many reasons to plant a garden: to add beauty to your surroundings, grow food or medicines, add value to your home, etc.  In recent years, islanders have become more and more interested in gardening to support our native ecosystem by providing shelter and food for native fauna.  Butterflies are always at the top of the list of insects that gardeners would like to support.  Many are amazingly beautiful, but also in real need of our help as their habitat is ever-shrinking due to human activities like development and farming.

Loads of native plants are a food or nectar source for caterpillars and butterflies, but we get the most questions about milkweed this time of year.  There are several species of milkweed that are native to the northeast, with more cultivated varieties in the trade as well.  We love these plants because they are easy to grow in full sun with average garden conditions.  The most popular of these is butterflyweed, Asclepias tuberosa, but we also stock others.

All milkweeds ooze a white latex sap when the leaves or stems are broken that prevents many insects from eating them.  However, monarch butterfly caterpillars have evolved to use milkweed as their only food source.  Many species of butterflies and other insects use the flowers as a source of nectar as well.  Milkweeds produce copious viable seeds in pointy pods.  When the pods mature and dry out in the fall it’s super fun to break them open and dispel the fluffy seeds on the wind!

Notable characteristics of the most commonly available milkweeds are listed below:

Asclepias incarnata – Swamp Milkweed.  The tallest milkweed that we stock at 36-48″ tall.  This plant is naturally found in sunny, moist areas like wet meadows and swamps with organically rich soil, but it adapts well to average garden conditions.  Flowers appear in July and August, varying in color from deep to light pink or even white.  The leaves of these plants are long and narrow, with a medium green color.

 

 

 

 

Asclepias syriaca – Common Milk Weed.  34-36″ tall.  This plant is found all over the island along roadsides, fields and disturbed areas.  They thrive in average soil in full sun.  The globe-like composite flowers appear in late June, persisting through summer.  The leaves are a dusty green, and wider than swamp milkweed.  This plant tolerates a wide variety of growing conditions, but is useful in areas with little supplemental water, as they are very tolerant of drought when established.

 

 

 

Asclepias tuberosa– Butterfly Weed.  The shortest of the common native milkweeds at 24-36″.  Found in sunny dry meadows, this plant makes a fantastic garden plant in dry areas without excessive irrigation. Make sure to plant it in full sun in average soil, and it will be happy for many years.  It has a bushy habit and narrow, ovate leaves.  The orange flowers appear in early July and persist for weeks in the height of summer.  Perennial plant of the year 2018!

 

Bluestar is one of my favorite plants of all time.  I like them because they are easy to grow with few, if any, pest and disease issues.  If sited correctly, they are super low-maintenance – just cut them down along with your other perennials at the end of the growing season or in early spring.  They have beautiful flowers, but also look great before and after flower, with disease-free green foliage in summer and yellow fall color.  Their bitter latex sap is said to make them unpalatable to deer (but the deer at 91 Somerset Road seem to like them just fine).  Several species and selections are available, each with its own characteristics.

Amsonia are long-lived herbaceous perennials that are native to the southern and south eastern United States.  Found in open meadows and fields as well as near lakes and wetlands, they tolerate a wide range of growing conditions.  In part sun, they tolerate less water, but planted in full sun, they benefit from consistent moisture.  Although they prefer fertile, well-drained soil, I’ve had good luck planting them in average garden soil with no additional fertility.  If the taller varieties are planted a shadier spot, they may benefit from a trim after flowering to promote a stockier habit that won’t flop open.

Their common name, bluestar is the perfect description of their flowers.  In late spring / early summer, these plants produce clouds of delicate, periwinkle blue, star-shaped flowers, each with five petals.  They don’t require deadheading, and look clean and tidy as the flowers fade.  These plants are right at home in the perennial border, but are also workhorses in prairie or meadow-style gardens.  The narrow-leafed varieties ‘String Theory’ and hubrichtii, in particular, contrast beautifully with bolder flowers like Echinacea, Shasta daisies, Black-eyed Susan’s, Crocosmia and the like.  Planted in a bright woodland situation, they would be excellent companions to Hostas and Heuchera as well.

The following plants are most commonly available:

Amsonia tabernaemontana:  Eastern Bluestar – 2-3′ tall and wide, with ovate leaves.

Amsonia tabernaemontana ‘Blue Ice’:  More compact than the species at only 12-18″ tall and 18-24″ wide.  Deep blue buds and lavender flowers.  Ovate leaves.

 

 

 

 

 

 

 

 

Amsonia tabernaemontana ‘Storm Cloud’: This Proven Winners selection emerges with near black stems and deep green leaves.  24″ tall by 38″ wide at maturity.  Periwinkle blue flowers.  Stems become green as season progresses.  Ovate leaves.

 

 

 

 

 

 

 

 

Amsonia x ‘Starstruck’: This hybrid bluestar blooms up to 2 weeks later than ‘Storm Cloud’.  It’s also more compact at 20″ tall x 30-38″ wide, with broader ovate leaves.

 

 

 

 

 

 

 

 

Amsonia hubrichtii:  Thread-leaf bluestar.  Narrow leaves appear needle-like, but soft and fluffy.  2-3′ tall.

 

 

 

 

 

 

 

 

Amsonia x ‘String Theory’:  A Proven Winners introduction.  Much like A. hubrichtii, but more much more compact.  18-22″ tall x 30=36″ wide.

 

There are so few plants that have a true blue flower in the garden – there seems to be loads of magentas, indigos, purples and violets; but so little blue.  Powder blue, in particular is very hard to get into the mix.  There are some annuals that have just that sort of blue, like Salvia uliginosa, and Tweedia, but most perennials have a purple or pink undertone to their “blue” flowers.  Stokesia laevis ‘Peachie’s Pick’ is in this vein, but it is very close to sky blue, to my eye.

These dependably perennial plants have glossy, thick medium green leaves that form a pleasing mound during the spring and early summer.  In high summer many flower stems arise from the clump, reaching about 18″ or so tall.  The entire plant is covered in aster-like flowers when the buds open, slowly over a period of weeks on sturdy stems. ‘Peachie’s Pick’ also looks great in a vase, so consider adding her to your cut flower selection.

Plant this beautiful but tough plant in good, but well-drained soil in full sun, and enjoy it for years to come!

At Surfing Hydrangea, we sell a wide variety of “bread and butter” plant material that landscapers are looking for every day, like cherry trees, catmint and fountain grasses.  Keeping lots of stock of those items is great for business, but it’s always the plants that I’ve never heard of, or seen in person that get me jazzed up for gardening again when I’m a little burned out.  My favorites are often the new introductions and hard-to-find perennial treasures that Britt brings in for the courtyard.

A few weeks ago, I was unloading a rack of plants when I came across a perennial with unique foliage, reminiscent of oak leaves.  I had never even heard of it, so I was delighted.  The grower describes the foliage of Macleaya microcarpa ‘Kelways Coral Plume’ as “commanding and tropical in appearance” and I definitely agree.  This thing is amazing.  The blue-grey leaves are about the size of my hand and run all the way up the stalk of this large plant.  When grown in sun, on well-drained fertile soil, plume poppy will reach 6 or more feet tall and spread out to occupy a space of about 4 feet.  The foliage is topped with feathery, coppery-pink flowers in high summer.  In fall, the leaves take on a tan hue, that fits right in with autumnal foliage.

I’ve been so interested in this plant that I’ve had one planted in our garden at the nursery so that we can enjoy it for years to come.  As I write this post, we still have a few in stock.  Why not give them a try in your garden?!

 

 

Ten years ago, when I was still gardening full time, most gardens had at least a few shrubby Caryopteris x clandonensis cvs.  This drought-resistant sub-shrub has grey green, deer resistant foliage during the growing season and airy blue flowers from late summer into the fall.  They look great planted en masse, or as accents in perennial borders.  But these plants are not without their problems.  If not grown in well-drained soil, they can rot over the winter or succumb to phytophthora root rot diseases.  And even though they are rated for our zone, long periods of exceedingly cold temperatures over the winter can also severely damage or kill them.  But there is a new Caryopteris on the scene, Caryopteris divaricata.

Caropteris divaricata is a completely different species of this plant, native to the Himalayas.  These are herbaceous perennials, dying completely down to the ground in winter and re-emerging from the crown in late spring.  They prefer full sun and fertile, but well-drained soil.  The green or variegated foliage has a distinctive aroma when crushed, reminiscent of old asparagus or green peppers.  I believe this odor is what makes them so averse to deer.  Although they flower late in the summer/early fall, they definitely have their merit.  I’ve always felt that using some tall, late-blooming plants in the back of the border is a great way to extend interest late into the growing season.  When so many other plants are blooming like crazy in summer, the foliage of these plants allows the eye to rest a bit, which makes the overall composition more enjoyable.  We’ve stocked two cultivars in the past: ‘Blue Butterflies’ and ‘Snow Fairy’.

I planted a big group of ‘Blue Butterfiles’ in the back of our garden last year, and have been very impressed with how sturdy their stems are and the plants overall size.  Year two, they are easily 6′ tall, filling an area between two large Hydrangeas very effectively.  I did notice considerable self-seeding this spring, but the volunteers were easily uprooted when they germinated and weren’t any trouble.  The flowers are profuse and very pretty when they arrive in September, but certainly best enjoyed close up.

 

I also planted some ‘Snow Fairy‘ in a different spot so that I could compare them.  This plant has been a real star.  So much so, that I am planning to plant another group further down this year.  The best part of this selection is the splash of white in the foliage.  When other plants are beginning to look tired with the heat of August, this Caryopteris is coming into its own.  The mid-green leaves have a varying degree of variegation, giving the plant a bright fresh look.  ‘Snow Fairy’ is shorter in stature than ‘Blue Butterflies’, making it more versatile.  Ours are just beginning to flower at 4′ tall.

 

When there seem to be fewer and fewer plants that are reliably deer resistant, it’s nice to have another plant to add to your arsenal.  I’d highly recommend giving Caropteris divaricata a try.

 

Being a professional gardener on Nantucket is a challenging career.  Most of our clients only spend a few months on the island during the summer.  Because the landscape as a whole must look fantastic for these few months, there is a lot of pressure on gardeners to keep the sunny border in full bloom from June until Labor day.  There are many ways this can be achieved, but it’s an ongoing process of planting, fertilizing, deadheading, staking, spraying various repellents and insecticides and replacing plants.  We battle the unpredictable weather, salty winds and never ending barrage of deer and rabbits who want to gobble up the flowers overnight.  Everything can be so much easier in the shade.  There is far less emphasis on COLOR! COLOR! COLOR!, allowing the gardener to focus more on combining textures to create a calmer atmosphere.  Astilbe, Hosta and Alchemilla are well-used in Nantucket’s shady gardens.  But for me, ferns are some of the most successful plants for the shade.

Ferns are wonderful, versatile plants for many reasons:

• Most thrive in dead shade where many other plants simply won’t grow.
• Many will grow in very wet/boggy soils.
• Others tolerate the dryer conditions under the canopy of mature trees.
• They are very low maintenance, only requiring a clean-up once a year.
• They are seldom bothered by insects of any kind.
• They combine easily with other shade-loving, broad-leafed plants like Hosta and Brunnera.
• Some are even evergreen, providing four season interest.
• And, unlike hosta, deer and rabbits seldom browse ferns.

We sell a wide variety of ferns at the nursery, but some of the most popular are:

LADY FERN, Athyrium felix-femina cvs:  This useful medium-sized fern (2-3′) grows best in fertile, moist soil with good drainage in light to dense shade.  It’s lacy fronds are a pleasant light green arising from a round clump.  It will tolerate full sun, with ample moisture, and is one of the few ferns that will thrive in the dry soils under large shade trees.  If grown in ideal conditions, lady fern will slowly form a colony that completely covers the ground.  Try ‘Lady in Red’ for a contrasting red stem.

 

JAPANESE PAINTED FERN, Athyrium nipponicum cvs:  This small to medium-sized (18-24″), colorful fern is best grown in fertile, evenly moist soil in light to dense shade.  The most striking feature of these ferns are their purple and silver coloring which contrasts well with other shade plants.  These are best kept in dappled to full shade as they will scorch in the sun.  The most readily available cultivars are ‘Pictum’, ‘Branford Beauty’ and  ‘Ghost’ but ‘Burgundy Lace’ is also a stunning plant to try.

 

HAY-SCENTED FERN, Dennstaedita punctiloba:  This tough small (to 2′), native fern is being spec’d more and more for large scale planting.  It grows best in moist, fertile, soils in light to dense shade. It’s upright to arching, lacy, triangular fronds are a pleasant light green.  If kept evenly moist, this is a fern that will tolerate full sun and poor soils.

AUTUMN FERN, Dryopteris erythrosora:  This is my favorite fern.  They grow 1-3′ tall, preferring rich, evenly moist soil and dappled light to full shade.  The young fronds emerge a coppery bronze and change to a glossy deep green as they mature.  New fronds continue to emerge throughout the growing season, so there is always some contrast between the young and mature fronds.  When they are happy, Autumn Ferns will spread to form a dense colony.  BONUS: these ferns are evergreen, and continue to look fresh long past frost.  Tidy them up in spring before new growth emerges to keep them looking their best.  ‘Brilliance’ is even showier than the species with brighter copper coloring

OSTRICH FERN, Matteuccia struthiopteris cvs:  Ostrich fern is a stately addition to shady gardens with minimal exposure.  These ferns have tall (3+’), medium/light green, erect, delicate fronds that are particularly suited to deep shade and moist fertile soils.  As they mature, the black root stock begins to rise above the soil level.  Never attempt to shorten the root stock, this procedure generally kills the plant.  Working with these ferns over the years, I’ve found them to burn out in August unless grown in deep shade, with constant moisture.  The fronds are also prone to easily breaking, so they are best used in the back of the shady garden, where they are less likely to get damaged.  Try ‘The King’ in areas where burning out is a concern; this cultivar seems to do better than the species in dappled light.

 

ROYAL FERN, Osmunda regalis:  These ferns are a New England native, performing well in moist, fertile soils in dappled to deep shade.  Depending on conditions, they will grow between 2 and 5′ tall with a loose spreading habit.  Royal ferns have a unique look among ferns; the fronds have leaflets that are much rounder than others, resembling plants in the pea family.  Their fertile fronds rise above the foliage, contrasting with the medium green leaves.  Like ostrich ferns, these ferns will form a root stalk as they age that should not be disturbed with pruning of any kind.

JAPANESE TASSEL FERN, Polystichum polyblepharum:  I’ve always admired this evergreen fern for it’s glossy green leaves and rounded habit.  In our garden it forms adjoining clumps that are 2′ tall and about 3′ wide.  We leave the foliage until spring to clean up, trimming it off before new fronds emerge.