Category Archives: Perennials and Annuals

Herbaceous plants

In Color: Hardy Succulents

Clockwise from left: Sempervivum 'Pacific Blue Ice', Sedum 'Angelina', Semeprvivum 'Carmen', Sedum album 'Coral Carpet', Sempervivum 'Topaz', and Sedum stefco

Clockwise from left: Sempervivum ‘Pacific Blue Ice’, Sedum ‘Angelina’, Semeprvivum ‘Carmen’, Sedum album ‘Coral Carpet’, Sempervivum ‘Topaz’, and Sedum stefco

It is early April here in New England, and as the snow retreats, a walk about the garden reveals color from unexpected plants…winter hardy succulents. Yes the early crocus and snowdrops are showing off, but they will come and go quickly. Since we’re still flirting with frosts and will not begin to see rich greens and bright pastels until the end of the month, the delicious burgundy and coral tones taken on by many hardy Sempervivum and Sedum provide a different color palette. These hardy succulents may not grab your attention when plant shopping, since many gardeners aren’t selecting plants at nurseries until warmer temperatures prevail. By late spring, the intense foliage hues change to more muted blue green and olive coloring. And of course, there are many more brightly colored blossoms to distract us.

If you’re taking a survey of your gardens right now, consider where you can use the rich, changing colors and textures that winter hardy succulents provide. They require minimal care and look good year round, especially the “evergreen” forms. Many are hardy into zone 3 plus are deer and rabbit resistant.  They ask only for sun and good drainage, and can winter over admirably in containers as well.

The receding snow (we had over 3′ at one point) did not harm Sempervivum ‘Carmen’ in the least.

The receding snow (we had over 3′ at one point) did not harm Sempervivum ‘Carmen’ in the least.

Anemone sylvestris

anemonesylvestrisweb Anemone sylvestris, is simply lovely and so innocent-looking, but perhaps it should be introduced to you as a potential ground cover. Commonly known as Snowdrop Anemone, this super hardy gem begins blooming in mid-late spring, producing nodding buds which open to 5 petaled white blossoms centered with a ring of yellow stamens. The blossoms, buoyantly dance on 12-18” stems, which are good for cutting, emit a soft early spring fragrance.   Although it is a European native, it looks right at home in naturalistic landscapes here in the US, spreading vigorously by rhizomes, and it is very effective for disguising early spring bulb foliage. The wooly seed heads that develop once the blossoms fade add visual interest later in the summer.  Occasionally, a small flush of flowering in takes place early fall.

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Anemone sylvestris is happiest in a rich well drained soil, and is hardy in zones 4-8. It is not fond of extreme heat, so best to hold off in southern gardens. There are no serious insect or disease problems and it is deer resistant.

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Mukdenia rossii ‘Karasuba’

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Mukdenia should be grown in more gardens and I will speculate why it is not; it has had the misfortune of having more than one Latin name, which gets confusing. For awhile the taxonomists declared it should be called Aceriphyllum rossii, which makes sense (Acer = maple) and the foliage does have exquisite rounded maple like leaves. The cultivar name has a translation that would be easy to remember as well, ‘Crimson Fans’.

I am sweet on its blossoms. In mid spring, Mukdenia produces sturdy 15-18” stems bearing rounded panicles of starry white flowers, just before and as the foliage appears, welcoming the bees into the garden. Mukdenia makes pleasant company for early blooming bulbs and Epimedium. The somewhat glossy, somewhat velvety, dark green foliage forms tight clumps to 12” tall, keeping their good looks all summer, then change vividly to brilliant shades of red when cool temperatures arrive in autumn. We’ve found that Mukdenia grows best with afternoon shade in a soil that has good drainage yet is fertile and adequately moist. You will be pleased to know it is hardy in zones 4-8 and is also deer resistant.

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Yucca filamentosa ‘Color Guard’

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Let us reacquaint you with an underutilized evergreen plant for cold climates.

Bold, colorful, architectural evergreen foliage. Dramatic creamy nodding lily flowers in early summer. Deer and rabbit resistant, it grows in poor and dry soils, and is perfectly hardy in zones 4-9. Why oh why don’t more landscapers and gardeners plant Yucca filamentosa ‘Color Guard’?

Yucca ‘Color Guard’ provides northern gardeners with a brightly colored vertical accent for mixed border plantings. Plants attain a foliage height of  24″, and when ‘Color Guard’ chooses to bloom, those creamy white lilies are held on 4-5′ tall towering stalks. Hummingbirds almost swoon over the plants in pour garden. We have it planted in a hot dry bed, with Acanthus hungaricus, Crambe maritima   Euphorbia ‘Ascot Rainbow’ and dwarf evergreens.

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Schizachyrium scoparium

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Schizachyrium ‘Blue Heaven’…summer, early autumn, late winter

Little Bluestem is an often over looked native yet very ornamental grass. This may be due to its intimidating Latin name but I suspect it’s because it is hard to document its charm in photographs…perhaps a video could capture its grace in motion. We’’ve grown the selection ‘Blue Heaven’ in our garden (see above) for a half dozen years, and it continues to impress us with its upright narrow foliage that transforms in color: almost powder blue in spring and summer, changing to plum wine tones in early fall, and becoming a stunning amber gold in early December.  We’’ve been impressed with how well it holds up to snow loads, springing upright as the white stuff melts away.

There are now a number of selected forms to choose from. ‘’Standing Ovation’’ is a bit shorter (3’-4’) than ‘Blue Heaven’ (closer to 4’). ‘Standing Ovation’ turns a very rich coppery red in the fall, later aging to a warm caramel color in winter. ‘’Carousel’’ is more compact and wide growing, growing 3’’ x 3’’, and its light blue green foliage takes on pink to wine tones in mid summer, with a multicolor effect, of pink, wine, and mahogany tones in the fall. We are excited about offering two new forms in 2015: ‘Schizachyrium ‘’Smoke Signal’ ‘ and ‘Twilight Zone’’. ‘’Smoke Signal’’, maturing at 3-4′,’ begins to turn red in late summer, but as the fall unfolds the color becomes a dark purple. ‘’Twilight Zone’’ gets a bit taller at 48-54””, with a narrow upright form. It holds its silvery blue color longer, developing dark purple highlights in autumn. These new forms reportedly share the same non flopping characteristics as ‘‘Blue Heaven’’  (aka ‘MinnBlue’).

Do you need more convincing to grow this grass? Here you go: Little Bluestem is drought tolerant once established, deer resistant, tolerant of windy sites, adapts to a wide range of soil types except very wet soils, and is exceptionally cold hardy…, zones 3-9.

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Tricyrtis hirta ‘Tojen

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Tricyrtis hirta ‘Tojen’

A must have plant for the late summer/fall shade garden is Tricyrtis hirta, commonly known as Japanese Orchid or Toad Lily. There are numerous cultivars; one I am especially fond of is the selection ‘’Tojen’’ , with has unspotted lavender, orchid like flowers held in loose sprays on sturdy stems above large lush foliage.

Toad Lilies enjoys a rich welled drained soil that stays adequately moist in the growing season. ‘’Tojen’’ is more forgiving of drier soils than other cultivars, but I recommended keeping the soil irrigated to keep plants at their best in late summer when they really show off. ‘‘Tojen’ grows 24-30”” tall by 30”” wide and is hardy in zones 5-8. Some great companion plants are Kirengeshoma palmata, Begonia grandis and late blooming Hosta such as ‘’Red October’’.

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Salvia splendens ‘Van Houttei’

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Salvia splendens ‘Van Houttei’

Bees, butterflies and hummingbirds are getting excited. It is August and the Scarlet Sage are beginning to bloom.

Tall Scarlet Sage is a form of Salvia splendens but should not be confused with the short bedding plants that are popular annuals sold in 6 packs. Native to tropical Brazil, this Dutch selection was named for the nurseryman Louis Benoit Van Houtte, known also as the father of Belgium horticulture. Leafy plants grow 3-4’’ tall and display dark red flowers accented with deeper red calyces from mid August to frost.

S. splendens ‘Van houttei’ enjoys a rich yet well drained soil in full sun or partial shade but requires adequate watering during dry spells. It is a tender perennial and will suffer when temperatures go below freezing. (hardy to zone 10). Plants will need to be dug and wintered over in a frost free area for the winter if grown in colder climates. For fresh stock, propagate by cuttings taken on new growth in the spring.

Only a couple of years ago this form of Salvia splendens had almost disappeared from cultivation after having been rediscovered twenty years ago. We forgot to save a stock plant a few years back, and this form does not come true from seed. At first we thought we could obtain new plants from other growers but to our dismay the only forms of tall Scarlet Sage being sold were impostors. The ordered plants would turn out to be either the orange red ‘’Faye Chapelle’’ or the red/purple form known as ‘’Paul’’. Both are good plants but they lack the beautiful coloring and looser form of the true ‘Van houttei’.  We were able to beg some cuttings off a gardener in western MA who had kept stock from plants he had saved for years. We now have a healthy supply and will be sure to take measures so we don’t lose it again.

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Dwarf Kniphofia

Kniphofia 'Creamsicle'

Kniphofia ‘Creamsicle’

One look at Kniphofia and you might be able to guess its native habitat is Africa.  Commonly called Torch Lilies, or Red Hot Pokers if you prefer, this member of Xanthorrhoeaceae family (not Liliacea, the Lily family) forms upright grass like foliage clumps from which rise spires of beautiful multi-toned tubular flowers beloved by bees, butterflies and hummingbirds. There are over 70 species, some of which are not hardy in northern climates. Most species bloom during northern hemisphere summers, but there are a few forms that will bloom when summer arrives in S. Africa, that is to say, December.

Recently Terra Nova Nurseries introduced a line of dwarf hybrid Kniphofia which they affectionately called the Popsicle Series. These dwarf selections have foliage that grows 12-15″” tall, with flower stems reaching 18-24″” depending on the cultivar. Blooming begins in mid July (for us), with flowering stalks continue to emerge right through September. We planted a half dozen of the form ‘‘Creamsicle’‘ last summer,  with its bright to pastel yellow orange coloring and they wintered over well, so this year we tried 2 new selections… ‘’Orange Vanilla Popsicle’, with a toffee orange to cream tones and ‘‘Pineapple Popsicle’ with a tart pastel lemon to chartreuse coloring.

Plant Kniphofia in a soil with good winter drainage and in full sun. It provides a 2’ exclamation point to beds when used in small groups, or would be stunning used en masse in a larger setting. Kniphofia is a great companion to Euphorbia such as ‘Ascot Rainbow’ and almost any Sedum. It can be sited in the foreground of a mixed shrub border…we have it coming up through a sea of steel blue Shore Juniper.

One more thing you might appreciate: deer do not like it!

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Kniphofia 'Pineapple Popsicle'

Kniphofia ‘Pineapple Popsicle’

Kniphofia 'Orange Vanilla Popsicle'

Kniphofia ‘Orange Vanilla Popsicle’

Gladiolus dalenii ‘Boone’

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You won’t think funeral parlors when you see this lovely species of Hardy Gladiolus. That’s right……I said hardy. For the past 6 years ‘Gladiolus dalenii ‘Boone’ has not only wintered over, (including our recent epic one)  but has multiplied, producing many bulb offsets in one of our raised planting beds. Elegant 3′ stems display apricot yellow blossoms which make lovely cut flowers in early-mid summer. It thrives in full sun and for the record, I will state it is hardy in zones 6-9 when grown in a soil that is well drained in winter. Incorporate a few shovels of sand into your soil when planting. For insurance it would be a good idea to lay a protective mulch of sterile hay or evergreen boughs in the colder parts of zone 6.

In cold climates (zones 1-5) you could easily lift the bulbs for winter storage and keep in a cool dry space that stays above freezing. Gladilolus dalenii ‘Boone’ can easily be grown from seed, and we have noticed some variation in color from seedlings…ranching from the softest of yellows to slightly deeper pale oranges, sometimes with darker orange highlights.

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Persicaria polymorpha

Persicaria polymorpha at dusk, photo by Paul Clancy

Persicaria polymorpha at dusk, photo by Paul Clancy

Mention the name Persicaria in horticulture circles, and you may raise a few eyebrows. Persicaria has a very bad cousin: Polygonum cuspidatum, commonly  known as Japanese Knotweed or Running Bamboo (but it is not a bamboo!), and this cousin can spread DREADFULLY. But please read on…

Persicaria polymorpha is commonly called Giant Fleece Flower, and this common name  describes it well. Within a few seasons, Persicaria polymorpha will reach 5′, maybe 6′ tall and form imposing clumps, increasing in width each season to 6′ or more. Talk about taking up space! In June and July, white Astilbe like plumes adorn the plant and the blooms seem to last and last. This is a great plant for a long distance view (think about its size and white color) and is memorable when viewed in the early evening light.

Here are the facts: Giant Fleece Flower likes average soil, or moist soil, or even very dry soil once established. It loves full sun but will grow in partial shade. It is a bold perennial and and adds contrast to the finer textured plants in your garden. Like Baptisia, it is one of the first herbaceous plants to attain good height in the spring.  It is deer resistant and long lived. I have yet to discover seedlings about, although it can be propagated by seed. Persicaria polymorpha is hardy in zones 4-9.

Consider Persicaria polymorpha when you are in need of a big, bold, hardy, long blooming, deer resistant plant.

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