Garden Notes

Garden Notes

Bluestar – Amsonia

, Posted by Brad MacDonald

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 'Blue Ice'
Image courtesy Walters Gardens, Inc.

 

 

 

 

 

 

 

 

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 'Storm Cloud'
Image courtesy Walters Gardens, Inc.
Amsonia 'Storm Cloud' Black stems
Image courtesy Walters Gardens, Inc.

 

 

 

 

 

 

 

 

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 'Starstruck'
Image courtesy Walters Gardens, Inc.

 

 

 

 

 

 

 

 

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

Amsonia hubrichtii
Image courtesy Walters Gardens, Inc.

 

 

 

 

 

 

 

 

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

Amsonia 'String Theory' fall color
Image courtesy Walters Gardens, Inc.
Amsonia 'String Theory'
Image courtesy Walters Gardens, Inc.

Hardy Kiwi

, Posted by Brad MacDonald

A great many years ago, I was visiting a friend’s farm back home in Nova Scotia and noticed a wild-looking plant covering a shed at the edge of the property. It was a huge tangle of broad leaves and tendrils from the soil up past the roof line. I had never seen anything like it, so I asked her what it was. She told me that it was a kiwifruit.  The only kiwi I was aware of were brown, fuzzy, tropical fruit that you could buy at the grocery store, so I just assumed she was off her gourd and moved on.  Since then, I have learned a lot more about plants and have grown to really appreciate the hardy kiwi species that are available for gardeners in the northern hemisphere. We have offered both Actinidia kolomikta (Arctic Kiwi) and Actinidia arguta cultivars in the past.

Hardy Kiwi are native to Eastern Russia, Korea, Japan and parts of China. These plants are extremely vigorous vines with twining tendrils that require strong support.  Their leaves are generally glossy-green and oval shaped, but there is variation among the cultivars and species.  Some are more serrated, or with red leaf-stocks and vines, others are even variegated with pink and white splotches.  Hardy kiwi have no particular pests to speak of (which is a marvel for a fruiting plant).  These kiwis are smaller than the typical grocery store kiwi, but the skin isn’t fuzzy, so they can be eaten right off the vine.

Like hollies, bayberry and many other plants, hardy kiwi is dioecious.  So, just like people, they have separate male and female plants.  In order to get fruit, it is important to plant either a self-fertile variety like ‘Issai’ or both a male and female of the same species. ‘Kens Red'(female), for example, should be planted along with another male Actinidia arguta in order to fruit.  They do require specialized care to produce fruit dependably, so it’s a good idea to do some in-depth research if fruit is the major goal.  Proper pruning and trellising can really help with getting a consistent crop.  That being said, I’d highly recommend growing them just for their ornamental value.

If fruit-set is just a bonus, why not give one or two a try and just see how they do?  Any garden situation where a Wisteria would be the traditional choice could absolutely handle a hardy kiwi vine.  They are equally, if not more, vigorous but with more handsome leaves.  They would look stunning covering a pergola or trained up along the side of a building. If allowed to grow across the slats of a pergola, this vine would provide quite a lot of shade below.  They could also do a great job of beautifying the fencing around a tennis court or pool, while providing good screening.

Including edible plants in primarily ornamental landscapes has been gaining in popularity over the last number of years.  As hardy kiwis are both attractive and productive, I think they are a perfect addition to the wisterias, roses and clematis that most gardeners are used to planting.  So, if you are up for a little challenge, and have some room – hardy kiwi is a great new(old) plant to try!

Thoughts on Pruning

, Posted by Brad MacDonald

I have to admit it – I love pruning.  There is something really great about the sound of my pruners clipping through the branches of plants that I’ve been growing all year.  After a long season of spacing, watering, fertilizing, deadheading and primping our shrubs to keep them salable, it gives me a weird glee to whack them back down to size.  For nursery stock, this is an essential part of keeping plants healthy and looking good, with top-growth in the right proportion to the roots.  It’s a little different with plants in the garden.

Novice gardeners often ask why pruning is important at all?  They look at the trees and shrubs in nature and figure they do just fine without pruning of any kind.  Why put in the work?  That’s a fair enough question.  The thing is, we expect a lot from the ornamental plants we grow in our yards and gardens.  We want them to look good and last a long time.  We want shade, but not too much shade.  We want them to fill their allotted space, but not overgrow it.  They need to be dense and flower profusely.  Plants in nature don’t have to live up to such high expectations.

If you think about a deciduous forest, under story shrubs are spindly and gawky, reaching up for as much light as they can get under the wide canopy of trees.  When a tree falls, light shines onto the forest floor and those spindly shoots take off, spreading up and out.  Shrubs that grow in meadows or at the edge of forests or wetlands, where sun is more available, tend to grow in tight-knit communities where they crowd each other, never achieving a balanced form.  As gardeners, we get to decide the spacing for our plants, giving them enough light and space to achieve the form we want.  We can plant them densely, as hedges, or further apart to allow them to grow into the shape their genetics want them to be.

Of course, ample water and nutrition are very important.  But good pruning can help a great deal to keep plants looking good and behaving the way we want them to behave.  With proper pruning, shrubs can be kept healthy and dense, with good form and produce the maximum show of flowers year after year.

We have lots of pruning resources on the website.  If you have questions, try using the search function in the top right hand corner of our website to find videos and written material that answers common questions.

 

Sweet Gale aka Bog Myrtle

, Posted by Brad MacDonald

I’m always on the look out for “new-to-me” plants that I think would work well for gardeners on Nantucket.  From time to time, we have big successes with those plants, but more often, landscapers just don’t know what to do with them.  When I came across Sweet Gale, Myrica gale, I thought it would be the perfect addition to our line up of native plants with some deer-resistance, so we brought some in.  They look great, but they don’t seem to be selling at all.  Sometimes we can encourage sales of lesser-known plants by putting them in a prominent spot so that customers will notice them.  I decided to make a display in front of the armillary in the courtyard, to see if that would drum up some interest, but to no avail.

You guys!  I really think these are great plants for us. You gotta give them a shot!  The cultivar we’ve stocked is called ‘Low Boy’.  These are compact (2-3′), rounded shrubs in the bayberry family.  They have semi-evergreen blue/green waxy leaves that are similar to common bayberry, but prettier.  ‘Low Boy’ is a male selection, so it won’t get fruit, but these plants are all about the aromatic leaves.  Sweet gale naturally grows in wet or moist soils in salt marshes and wetlands, so it would be perfect on Brandt Point or any low-lying area of town.  That being said, these plants will do well anywhere they are properly irrigated in full to part sun.  Although I haven’t seen them planted yet, I think they should have good deer resistance, to boot.

The texture, shape and size of these plants is so pleasant that they would work well in a number of design styles and a wide rage of applications.  Sweet gale is the perfect plant for use in loose, coastal gardens paired with summer sweet, switch grass, native sedges, and rose mallow.  But they would also make a great component in a naturalistic matrix planting or used as a vast drift in the New American Landscape style.  I could even see them used to create a super cool minimalistic, planting with purple smoke bush as a back drop.

Try a few!  You’ll like them.

Crape Myrtle Trees

, Posted by Brad MacDonald

Everyone loves flowering trees.  When in bloom, they can change the entire look and feel of the landscape, especially if there are many trees planted throughout a property.  Ornamental cherries and pears make up the vast majority of the flowering trees that we sell at the nursery, but there are lots of lesser-used trees that are also very beautiful.  In recent years, we have had more and more customers including Crape Myrtles in their gardens.

The genus Lagerstroemia has more than 50 species, but most of the landscape-worthy plants we offer are within the species indica and fauriei or hybrids of those.  These deciduous trees and shrubs are native to India and Asia, including China, Japan and Korea.  They prefer full sun and fertile, moist, but well-drained soils.  Crape Myrtles come in a wide range of sizes and flower colors.  The leaves are a deep, lustrous green, and often turn amazing shades of red and orange in the fall.  Most cultivars have handsome bark, that exfoliates, giving the trunks an interesting mottled appearance.  The enormous paniculate (botanical jargon for many flowers joined together on a branched central stalk) flower clusters are borne on the tips of the branches and generally open in September on Nantucket.

Because these trees are technically marginally hardy here, we always suggest planting them in a protected spot in town.  In reference to Crape Myrtles, the authority on woody landscape plants, Dr. Michael Dirr states, “…-5 to -10 F is about the breaking point between a woody plant and herbaceous perennial.”  However, there are quite a few large Crape Myrtles on the island that have survived some of the colder winters we had a few years ago.

Crape Myrtles flower on new wood, so they are often pruned severely while dormant, forcing a lot of new growth annually.   That being said, I much prefer the look of a tree that is artfully pruned to a balanced framework instead of heading the entire plant back to an arbitrary height.  When pruned this way, they can have a lovely shape that is nice to look at, even when the branches are bare in winter.

We’ve had many cultivars over the years, but a few of the most common are listed below with their attributes:

  • ‘Biloxi’:  Pale pink flowers on a 20′ tall tree.
  • ‘Centennial Spirit’:  Wine red flowers on a 10-20′ tall tree.
  • ‘Hopi’:  Light pink flowers on a semi-dwarf tree – 7-10′ tall.
  • ‘Muskogee’: Lavender flowers on a large shrub or small tree – 15-20′ tall.  Britt’s favorite!
  • ‘Natchez’: White flowers on a vigorous, small tree – 20′ or more tall.
  • ‘Sarah’s Favorite’: White flowers on a vigorous, small tree – 20′ or more tall.  Anecdotally, a better plant than ‘Natchez’.
  • ‘Sioux’: Dark pink flowers on a large shrub or small tree – 14′ or more tall.
  • ‘Tonto’: Fuschia-red flowers on a semi-dwarf tree – 6-8′ tall.
  • ‘Tuscarora’: Coral-pink flowers on a large shrub or small tree.  15′ or more tall.

 

 

Ornamental Grasses 201 – Nice Natives

, Posted by Brad MacDonald

Although most of the garden-worthy grasses we sell as ornamentals are exotic, there are many beautiful native grasses to choose from in commerce.  Whenever possible, we like to encourage our customers to try using native grasses.  They grow well, require little care, and have evolved with the natural vegetation of the island.  Native plants contribute to the overall beauty and health of our planted landscapes as well as the native ecosystem.  They also support the fauna that has developed here over thousands of years.

There are many native grasses found here, growing in a wide variety of habitats; from the shore line into the more fertile interior areas of the island.  The most popular species of native grasses that we sell is Panicum virgatum, commonly called Switch Grass or Panic Grass.  There has been a lot of work done with these grasses over the years, so there are many cultivars to choose from with a variety of heights, habits and colors to the foliage.  For more information on some of the various Panicum grasses check out this post: https://surfinghydrangea.com/switch-grass-2086

Another of our naturally-occurring grasses that is slowly becoming more popular is Schizachyrium scoparium, Little Bluestem.  If you walk your dog at Tuppancy Links, you are very familiar with this grass: it’s one of the predominant species found growing on the links, especially beautiful in the fall when it takes on coppery-red, orange and auburn hues.  Backlit by the sun at the end of the day, it’s magic.  Little bluestem grows best in full sun on moderately fertile, well-drained soils without much additional water.  The narrow bluish foliage appears in mid to late spring from the base of mostly clumping plants.  By August, the plant reaches its full height of about 2-3′ and begins to flower.  The flowering stems rise above the foliage, producing tight sprays of fluffy flowers.  Gardeners have found that when little bluestem is over-irrigated or grown with too much fertility it can get floppy – avoid this problem by planting it in un-amended soil and only watering during establishment and prolonged periods of drought.

Whether planted in drifts or sprinkled here and there among perennial flowers, this is a wonderful addition to almost any island landscape.  Several cultivars are available including ‘The Blues’ whose blue foliage is steaked with purple and accented with red stems.  ‘Standing Ovation’ is another great cultivar that is touted to be reliably sturdy with an upright, non-flopping, habit.

For a plant that will tolerate shadier conditions, try Carex pensylvanica, Pensylvania Sedge.  Although, it’s not technically a true grass, this short (6-12″) plant has a delicate, grassy look with arching foliage and spreads by rhizomes to make a pretty ground cover.  It looks especially nice in dappled shade under deciduous trees but grows well in fully shaded areas.

Several other grasses native to North America are also well-worth planting.  For a fine textured, loose look  consider Sporobolus heterolepsis, Prairie Dropseed, Deschampsia cespitosa, Tufted Hair Grass or Descampsia flexuosa, Crinkled Hair Grass.

 

Ornamental Grasses 101

, Posted by Brad MacDonald

Ornamental grasses are beautiful, deer-resistant and easy to grow.  Although there are many lovely native grasses, the majority of ornamental varieties are introduced from Asia.  We sell hundreds upon hundreds of these plants each year and their popularity seems to keep growing.

Most ornamental grasses are clumping, perennial, warm-season grasses that will come back for years.  Although there are many species and varieties available, the most popular today are Maiden Grasses, Miscanthus sinensis and Fountain Grasses, Pennisetum alopecuroides.  If sited in full sun and grown on average soil, these plants require little care – just cut them back to a few inches above the ground during the winter and irrigate during dry spells in the summer.  Maiden grass do best if dug and divided every 5 years or so, which is a major undertaking!  Make sure to keep this extra step in mind when planting them, as the clumps can get very large as they age.

The most popular grasses are listed below:

Miscanthus sinensis ‘Gracillimus’:  Gracillimus Maiden Grass.  The most common large ornamental grass sold.  Broad, vase shaped form, reaching 6′ tall.  Deep-green, finely textured blades have a narrow white mid-rib.  Silver/buff-colored flowers appear above the foliage in late summer and persist into the winter. After a number of years, the clumps will spread to 3+ feet wide, with the foliage spreading out to at least 5 feet.    The dense crown of the plant may die out in the center, signaling that it’s time to divide.  Division is best done in late spring, just as new growth has begun to emerge.

Miscanthus sinensis ‘Adagio’: Adagio Maiden Grass.  Another large grass, similar to ‘Gracillimus’, but a foot or two smaller in size overall.

Pennisetum alopecuroides ‘Hameln’:  Dwarf Fountain Grass.  Rounded grass with a cascading habit, 2 – 2.5′ tall and wide.  Mid-green foliage changes to yellow in fall.  Fluffy, bottle brush-shaped flowers appear in mid August above the foliage on narrow stems.

Panicum virgatum, cvs.: Switch Grass.  Many varieties of this native grass are now in commerce.  Generally, upright 3-5′ tall.  Airy inflorescences appear in mid-summer.  Breeding in these grasses has focused on improved form and foliage color.  ‘Heavy Metal’, an old favorite, has a metallic blue sheen to the leaves and average height of 5′.  For a more compact variety, try ‘Cape Breeze’ a dwarf that stays about 2.5′ tall.  Many other cultivars are available with purple or blue foliage, some reaching 8′, making a major statement.  For more information on switch grass check out: https://surfinghydrangea.com/switch-grass-2086

Nassella tenuissima aka Stipa tenuissima: Mexican Feather Grass.  One of the few cool-season ornamental grasses, this plant has gained in popularity in recent years, especially used as a mass planting.  The light green, fine-textured foliage emerges in late spring.  This fresh growth appears upright early in the growing season, but becomes more arching as it elongates to 1-2′ in height, with a more fountain-like habit.  In mid-summer the airy inflorescences emerge and the foliage changes to a beachy, buff-tan.

These are only a handful of the grasses that we stock.  On any given day, we will have many more to choose from.  We’d be happy to show them to you.

Calamint

, Posted by Brad MacDonald

Nearly every gardener that has visited the nursery this year has spoken about the uptick in rabbit and deer damage this year. The rabbits are ravenous and the deer are nearly impossible to keep out, short of installing a professional farm-grade border fence. These animals have become more than an nuisance – they are a serious problem.  Year after year, the list of plants deer and rabbits won’t destroy has gotten much shorter.  Russian sage, catmint, lavender and grasses are still mostly reliable (although we had a whole crop of catmint eaten early this spring).  Another favorite of ours is calamint, Calamintha nepetoides cvs.  

The fuzzy, menthol-scented leaves of this plant make it highly resistant to rabbit and deer browsing.  And it blooms for months – seriously!  This compact plant is covered in tiny white or blue flowers from mid-summer well into the fall.  It makes an excellent groundcover, planted en masse, but also looks great in the front of mixed perennial borders.  Calamintha does seed around a little bit, but I’ve never felt it to be a problem.  Another consideration with this plant is how late it is to come up in the spring.  Because it is one of the last perennials to get going, I often plant it closer than recommended so that I get the coverage I want earlier in the season.  If you want to get the best out of this plant, site it in a sunny location with well-drained, healthy soil.  There are several cultivars available for sale, with newer introductions entering the market recently.

  • Calamintha nepeta subsp. nepeta:  Icy blue/white flowers.  Fuzzy leaves.  Spreads a little more readily than others as stems root along the edges of the clump.  1-1.5′ tall.
  • Calamintha nepetoides ‘Montrose White’:  Clear white flowers that appear icy blue in cooler weather.  Less prominent fuzz on the leaves.   Leaves appear darker green than other varieties, setting off the flowers well. 1-1.5′ tall.
  • Calamintha nepetoides ‘White Cloud’:  Clear white flowers.  Fuzzy leaves.  1-1.5′ tall.
  • Calamintha nepetoides ‘Blue Cloud’:  Very similar to white cloud, but with icy blue flowers.
  • Calamintha nepetoides ‘Marvelette Blue’:  The largest and most saturated flowers we’ve seen on a Calamint so far.  Earlier flowering than other varieties.  8″ tall.

Stokes Aster ‘Peachie’s Pick’

, Posted by Brad MacDonald

 

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!

Plume Poppy

, Posted by Brad MacDonald

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?!