Category Archives: Perennials and Annuals

Herbaceous plants

Conoclinium coelestinum ‘Cory’

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A new name for the Hardy Ageratum. Formerly Eupatorium coelestinum, the plant taxonomists have bestowed the name Con-oh-clin-i-um on this late summer into fall blooming plant. The species name co-el-est-in-um means heavenly. Clusters of heavenly sky blue flowers atop 18-30″ stems bloom in August and September, attracting butterflies and pollinators. Conoclinium enjoy average, evenly moist soil conditions and spreads by stolons, creating a healthy patch where happy. It makes a lovely cut flower and is hardy in zones 5-8.

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Summer Meadow Rues

As the 4th of July rolls around, the early June show of Baptisia, Peonies, Iris and Cranesbill is fading, and its time to focus on high summer performers. I could not be without the dreamy clouds of  the summer blooming Meadow Rues, or botanically speaking Thalictrum, with their sprays of dainty small blossoms on tall stems, creating a seductive haze above the knee high plants in the garden.

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Thalictrum ‘Splendide’

First there is ‘Splendide’, the first of the French breeder Thierry Delabroye’s introductions with its slightly larger soft lavender flowers. ‘Splendide’ is statuesque…it can reach 7′ in a rich soil, and may need staking when the branched stems are heavy with buds.

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Thalictrum ‘Splendide ‘White’

Thalictrum ‘Splendide Whiteis perhaps my favorite. Another selection from Thierry Delabroye, this white selection takes the place of Baby’s Breath in the border with its 3′ to 4 .5′ stems above delicate Columbine like foliage. Sprays of pearly buds  burst into 1/2″ 5 petaled blossoms with greenish white stamens. Blossoms continue for weeks, and make exquisite cut flowers.

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Thalcitrum delavayi ”Hewitt’s Double’

And then there is this older form of the species, T. delavayi,  ‘Hewitt’s Double’, which bears its inflorescence on 3-4′ stems above dainty Maidenhair fern like foliage. It has shown a preference for excellent soil drainage in winter, but enjoys an evenly moist soil during the summer months.

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Thalictrum rochebrunanium

Last but not least, is the most familiar form Thalictrum rochebrunanum ‘Lavender Mist’ which can easily grow 4-6′ tall in a rich somewhat moist soil.  Sprays of lavender buds open to show 4-5 petaled blossoms with prominent yellow stamens in July and August.  T. rochebrunianum can self sow where it is content.

Thalictrum are members of the Ranunculus family which includes, Anemones and Buttercups. They enjoy average to rich soil with ample moisture during the growing season and full or half day sun. T. delavayi is hardy in zones 5-8, and the rest are more cold tolerant and are hardy in zones 4-8.  And oh, yes, they are not favored by deer or bunnies.

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Allium ‘Millenium’

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Allium ‘Millenium’ in the early morning light.

What’s not to love? This Allium hybrid from Mark McDonough is one of the key plants for solid bloom in July and August in our perennial and mixed beds. 2″ lavender orbs on sturdy 12-18″ stems provide color for weeks. It doesn’t mind the heat and dry soil, and  bulks up quickly, and can be divided in the spring if you want to spread it around. Of course it is attractive to butterflies and pollinators. When blooming fades, cut back the stems, or leave the heads on to dry and add textural interest. Deer and rabbit resistant and it is perfectly hardy in zones 5-9.

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Smitten by Solomon’s Seal

Polygonatum x hybridum 'Striatum'

Polygonatum x hybridum ‘Striatum’

Unfurling

Other forms….Unfurling

Dancing

Dancing

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Dangling

Just a few images to share….loving the various species and  forms in the genus Polygonatum (Solomon’s Seal).  We currently have about 15 selections, ranging in size from tiny 6″ Polygonatum humile to  6′ selections of P. biflorum. and are always seeking out more.

quick facts: Solomon Seals is in the family Asparagaceae. Most forms are hardy in zones 5-8, (a few in zones 3 & 4). They slowly spread by jointed rhizomes, and enjoy well drained soil in partial to full shade. Long lived and almost indestructible, Solomon’s Seal is one of those plants that holds its good looks with little care all season.

Asparagus Ferns to Know and Grow

Perhaps your grandmother had a big hanging basket of Asparagus Fern on her shady porch…you probably didn’t think much about it, but there it lived, thriving with little care, living in the same pot for what seemed to be years on end. Yes-sir-ree…a testimony to a plant which could thrive on neglect.

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Just planted….Asparagus setaceus plumosa, with 2 begonias in an 8″ square pot.

Despite their fernlike ambience, this group of foliage plants are not ferns at all, but members of the Lily family (Liliaceae). An inspection of the root system reveals a mass of bulb-like tubers, (think lily bulbs). Being pot bound doesn’t discourage their vigor and although they like bright light, Asparagus Ferns can exist satisfactorily with quite a bit of shade. They do not need a constant supply of moisture, and prefer a soil that is sharp draining. Take note: Asparagus Ferns make great companions to Begonia  which like similar conditions… bright light to shade, and a soil that doesn’t stay wet.

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Asparagus densiflorus ‘Sprengeri’ (L) and densiflorus ‘Myersi’ (R)

The most familiar species is A. densiflorus ‘Sprengeri’, known for it’s arching stems of apple green narrow leaves. (For those who need to be on top of all things botanical…the genus is now Protasparagus, but that may be too much information for some. ) The next most commonly encountered form is the Foxtail Asparagus, A. densiflorus ‘Myersi’, with its  gorgeous chunky plumes.

Now, let me introduce you to  a few siblings, which offer variety but require the same easy care, and of course are suitable as cut greenery for arrangements.

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Clockwise from upper left: A. densiflorus ‘Cwebe’, A. setaceus plumosa, A. setaceus pyramidalis, and A. macowanii

Asperagus densiflorus ‘Cwebe’ is not dissimilar to Grandma’s form, but ‘Cwebe’ tends to be more upright, growing, to 18-20″ tall, and has an interesting bronze tint to the new growth. Asparagus setaceus plumosa is  very lacy,  and is familiar to those who purchase cut greens for arranging.  Asparagus setaceus pyramidalis also has lacy, fine textured foliage with an upright thrust. Perhaps the sweetest of all is Asparagus macowanii, commonly called Ming Fern, with very delicate forest green foliage. As a young plant A. macowanii  is quite small in stature, but if grown in a conservatory or outdoors where it is hardy, it can reach a height of 5’ at maturity.

Anemone x ‘Wild Swan’

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Like everyone else, we have fallen for Anemone ‘Wild Swan’.  Exquisitely simple white petals reversed in periwinkle blue surround a boss of yellow stamens in anemone like fashion and are held on 18-20″ stems. A hybrid of Anemone rupicola and possibly hupehensis,  it was selected by British plantswoman Elizabeth MacGregor a decade ago, and took her years to build up stock.  At last it debuted at Chelsea Flower Show in 2011, and caught the eye of many a gardener on both sides of the pond.

We finally acquired some tissue culture propagated plants in 2015. In its first year in the garden, ‘Wild Swan’ began blooming  in late spring,  then rested once the summer heat set in.  We found that in September,cooler temperatures encouraged  a second round of flowering stems. (In cool summer climates, the show may in fact carry on all summer. ) All of last year’s plants have come back up in the garden, after inconstant winter weather. We’re hoping for a more robust show this year.

Anemone x ‘Wild Swan’ enjoys a soil with good drainage and full sun or partial shade. It is hardy in zones 5-8.

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Digiplexis x ‘Illumination Flame’

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Sometimes amazing things happen when you cross similar plants from different regions: Digitalis (European Foxglove) and Isoplexis (Canary Island Foxglove. The result: beautiful perpetual blooming 3′ spires of tubular flowers, which are colored sunset coral in bud and then open, exposing yellow throats with hints of apple green. This particular selection, ‘Flame’, is the first of the Illumination series introduced by Charles Valin which won the prestigious award of Best in Show at the Chelsea Flower Show in 2012.

Last year we grew Digiplexis ‘Flame’ in a large pot. It began to bloom in early June and carried on for months, well into September. The blossoms are sterile, which tricks the plants to be constantly in flower.  We brought the container into the cool greenhouse to winter over and it’s back up and about to start the show all over again. This year we’ve also planted it in our garden beds for the constant color it provides. We envision it as the vertical complement to Dahlias and Summer Phlox in a sunny, enriched , well drained border which gets an average amount of irrigation. I can attest that the hummingbirds were regular visitors, as were bees and butterflies, and I suspect it is deer resistant as well.

Because Digiplexis inherited its hardiness genes from its Canary Island parent, it will only winter over outdoors in zones 8-10, (although one of our customers bragged to me the other day that hers wintered over outdoors in a protected spot in zone 7).  Dig  up the roots after the first frost, as you would a Dahlia and store in a cool spot that stays above freezing for the winter. Gardeners in warmer winter climates don’t have to worry about this, and I can only imagine the display in their garden year after year!

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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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