Tag Archives: drought tolerant

As summer ends…

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A+ rating for drought tolerance…Yucca ‘Color Guard’ with Jackman’s Blue Rue, Succulents, Sedums and dwarf conifers. Oh yes, and the amazing yet vicious Solanum quitoense.

Not sure if I am truly sorry to see the summer of 2016 end. There have been days that I’ve thought that an early frost would be a blessing as I dragged hoses about, trying to coax vibrancy into a garden getting more tarnished looking by the day. The forecast for rain never proved to be true, and the number of very hot days set a record. Still, the optimistic gardener within always wins out. Yesterday, I walked about the garden to see what plantings held their own despite the cursed weather. Here’s what I saw.

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The Oakleaf Hydrangea ‘Peewee’, with flowers aging to russet brown, but with fresh foliage, despite no irrigation.

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Crambe maritima (Sea Kale) thrived, and swallowed up the younger plants nearby.

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Agastache ‘Black Adder’, with nearby Amsonia hubrictii beginning to turn golden for fall.

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Deep rooted Lespedeza ‘Gibralter’ could have cared less about the drought.

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Little Eucomis ‘Dark Star’, petty in flower and in leaf, with nearby red Heuchera

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Succulents by the road fended for themselves admirably

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Fruit finally formed during  the 3rd week of August on the giant pumpkin. We’ll see…..

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Our overly ambitious cut flower garden….did I know I wouldn’t have extra time for fresh arrangements, ands  planted Celosia and Gomphrena which could also be cut and then dried?

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You are not seeing the mildewed foliage (intentionally), of the lovely Queen Red Lime Zinnia…

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The blush pink beauty of Dahlia ‘Cafe au Lait’

And so, as I prepare for fall, certainly all was not lost. The garden gave us butterflies and bees, and yes, beauty, in addition to many challenges.  I am game for next year…are you?

Summer Hardiness–which plants survive the heat?

Yucca 'Color Guard', Vernonia lettermanii and Crambe maritima have performed despite the heat and drought .

Yucca ‘Color Guard’, Vernonia lettermanii and Crambe maritima have performed despite the heat and drought .

Well, we know we’re not alone, but here in southern New England, we’ve had an exceptionally hot dry summer. The amount of precipitation in our area has varied due to isolated showers, but I would guess here at Avant Gardens we have totaled less than 1 inch during the past 75 days. Lack of rainfall plus high humidity, coupled with daily temperatures in the high 80s and 90‘s can have an effect on plants. (Many plants begin to suffer physiological damage when temperatures remain above 86F or 30C)

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This brings up the classification of plants rated for Summer Hardiness. The American Horticultural Society (AHS) has created a Summer Heat Zone map of the US.  Regions having less than 1 day with temperatures above 86F (30C)  are classified as zone 1, and on the other end of the spectrum, the areas having the most days with high temperatures are classified as zone 12. This may correlate with the familiar USDA Winter Hardiness Zone Map (which rates average lowest temperatures) but in some cases it does not. Folks in the southern US have learned that Summer Heat Zone Hardiness is definitely a criteria when selecting plants. The above map will need regular adjustments now that global warming is causing extreme temperatures worldwide, and northern gardeners will have to pay heed to which plants will survive/perform with higher summer temperatures.

We’ll be ruling out more plants that do well in our gardens in the future, I’m afraid, as climate change continues to affect what we can and cannot happily grow.

Have you come to the conclusion that some plants, which once thrived in your gardens,  no longer will? Which plants have you found best withstand our ever warmer drier summers?

The Other Hardy Hens & Chicks

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Jovibarba heuffelii with small Sempervivum, Echeveria & Orostachys in the background.

The most familiar hens and chicks are in the genus Sempervivum. I’d like to introduce you to the  less familiar with same common name which are classified in the genera Jovibarba, Orostachys and Rosularia.  All are members of the Crassulacea family.

A rosette of Sempervivum flowering

A rosette of Sempervivum flowering, but with a number of offsets surviving.

Like Sempervivum, all are monocarpic, which means when the main rosette erupts into flower, it will set seed and cease to exist. (You can see why it is a good thing that many offsets of new plantlets have been freely produced.)

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Jovibarba hirta ssp arenaria

The genus Jovibarba is sometimes classified as a sub genus of Sempervivum.  Jovibarba is distinguished by blossoms bearing pale green to yellow 6 petaled flowers compared to Sempervivum’s 10-12 petaled pink blossoms. There are only 3 species in the genus: globifera, hueffeli and hirta. J. globifera and hirta freely produce stoloniferous offsets but  J. heuffelii’s “chicks” are tightly attached to the crown, and need to be severed to propagate more babies. J. hirta ssp arenaria  forms dozens of delightful miniature rosettes (1/4-3/4”) of pale gray green leaves covered with tiny hairs. Cool temperatures bring out red foliage highlights. Grow in a lean soil with sharp drainage in hardiness zones 5-9.

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Orostachys spinosus

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Orostachys minutum

Orostochys is a slightly bigger genus…it includes the more popular O. iwarenge (Dunce caps) as well as several others that are garden worthy subjects. The mature rosette of O. spinosus gives the appearance of a silver sunflower with an array of silver quilled foliage surrounding a center of congested tiny tight leaves. It is hardy to zone 4-9, but requires very well drained soil. O. minutum (also listed as O. spinosum minutum) is quite petite as the specific name suggests, producing clusters of 1/2-1” rosettes of blue gray foliage. It  would make an excellent alpine trough plant.

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Rosularia muratdaghensis

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Rosularia serpentinica

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Rosularia chrysantha

The genus Rosularia includes about 35 species. We have grown R. muratdaghensis, R. serpentinica, and R. chrysantha. Both R. muratdaghenis and serpentinica form tight mounding rosettes of gray green foliage, accented with red tones in cooler temperatures. R. chrysantha has a mat forming habit,with rosettes of soft velvety green leaves. All 3 species demand lean soil with excellent drainage and are are hardy in zones 5-9.

In bloom: Tender Succulents

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Flowers of Graptoveria ‘Fred Ives’

Most of us select our ‘tender” succulents by virtue of their unique forms or foliage in desert tints of sage green, blue gray, dusty rose, plum, khaki gold. A few put out flowers during our northern hemisphere summers, but many warm winter succulents bloom when the day length is shorter…mid-late fall, winter, and early spring.  These succulents add astonishing color to a windowsill display while we wait for spring to really settle in.

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A peak at some of our Aloes in bloom.

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Gasteraloe ‘Green Ice’…a cross between an Aloe and Gasteria

I’ve been collecting “tender succulents” for more than 15 years, and one of the frustrating things I constantly come across are mislabeled plants. We now have an excuse to visit southern CA more frequently as one of our sons is living there, and since this is where more succulents are grown than anywhere else, I have made it my mission to visit botanical gardens and nurseries from Santa Barbara to San Diego in search of proper names. The most common succulent genera are Aloe, Crassula, Echeveria, Gasteria, Graptopetalum, Kalanchoe, Pachyphytum and Sedum.

What makes things very curious is that there’s been a lot of inter breeding going on, and by that I mean crossing one genus with another. For example, Echeveria crossed with Sedum becomes Sedeveria.  Because these genera are so closely related (many are in the Crassulaceae family) this works, and some interesting new plants have been introduced. This does however complicate identifying misnamed plants. The foliage isn’t always the tell tale sign; the flower formation can give better clues, but even then…take for example Graptoveria ‘Moonglow’, a cross between Graptopetalum and Echeveria.

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Graptoveria ‘Moonglow’

The flowers of Echeveria tend to be bell shaped with many variations: tightly closed, flared, chunky, narrow and are held on short or even tall stems that can be terminated with a few blossoms or multi branched. Graptopetalum blossoms are star shaped with prominent stamens and are held on upright stems in branches of a few to many flowers. The flowers of Sedum are held in terminating clusters of star shaped inflorescences. The intergeneric crosses display a mix of these flower formations, and here is where further research is required. I plan to continue to study the differences.

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Sedum ‘Limeglow’

Photo documentation is essential in keying identity. I now have a set up for plant portrait taking, and will continue to photograph the various flower forms as  plants continue to open bud.  Here are a few photos of various succulents in flower.

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Echeveria ‘Dondo’

Mystery Echeveria…purchased as 'Fleur Blanc'

Mystery Echeveria…purchased as ‘Fleur Blanc’

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Mystery Echeveria…also purchased as ‘Fleur Blanc’

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Pachyphytum oviferum…or “Moonstones”

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Echeveria ‘Lola’

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Echeveria parva

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Sedeveria ‘Harry Butterfield’

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Mystery Sedeveria

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Sedeveria blossom

I have yet to find an authoritative source, online or in print, documenting and clarifying information on succulents. It is a challenging task, for sure. Do you have a resource or guide you refer to? Please share if you do.

 

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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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’

Aster oblongifolius ‘Raydon’s Favorite’

Aster oblongifolius ‘Raydon’s Favorite’

Just look at this plant in mid October!

A mass of bright lavender blue flowers reward those who have patience and foresight, since Aromatic Aster (its common name) is not much to look at in May and June. Still, it is undemanding all summer long, tolerating dry soil and neglect. In late September, you begin to notice the buds develop color and in a few weeks, it is a sight to behold.

Botancially speaking this Aster has been reclassified as Symphyotrichon, but the gardening public seems to be ignoring this name. ‘Raydon’s Favorite’ typically grows 2-3′ tall, and 3′ wide. It has a little brother, the selection ‘October Skies’ which stays more compact (under 2′) if you are in need of a selection with less height. Aster oblongifolius is super hardy, tolerating even the cold climate of zone 3. It can be dusted with a bit of frost and still look unfazed.

Aster ‘Raydon’s Favorite’ is a perfect compliment to all the oranges and golds of autumn, especially the perennial mum, Dendranthema ‘Sheffield Apricot’ and  the colorful Dwarf Witch Alder, Fothergilla  ‘Blue Shadow’.

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Euphorbia corollata

Euphorbia corollata

I think I know the reason why few people grow this easy care, refreshing native plant, commonly called Prairie Baby’s Breath: plants, even young seedlings, transplant poorly. The happiest plants have planted themselves, like this clump that adorns our front walk entry right now; it was sown in situ. Of course, you need to have a mother plant nearby to have these babies come up on their on accord, and that’s a “chicken or the egg” dilemma. We always have a few potted plants here at Avant Gardens but because they usually look weak and spindly, they are not an easy sell….unless you happen to visit our nursery and gardens in August. Now, everyone marvels at this “different baby’s breath” when they pass by.

Once established, Euphorbia corollata asks for little but sunshine and well drained soil. It begins to bloom heavily in mid July and carries the show through the month of August. I haven’t tried it as a cut flower, (it is a spurge and has that milky sap), but maybe I should experiment with sealing the stems with a flame, which will prevent that sap from poisoning the vase water. Perhaps it would be prudent to stress that some people are very sensitive to Euphorbia sap and can get serious skin irritations when exposed to it. Fortunately for me it has never been a problem.

Euphorbia corollata is hardy in zones 4-7. We planted it in our gardens more than 20 years ago, and it is still there, a testimonial to it’s longevity, often popping in new spots, especially well drained pockets. Should it sow where you don’t want it, just pull it out. In addition to being quite attractive to beneficial insects, such as bees and wasps, it isn’t a plant deer or rabbits will likely munch on, since it is poisonous if ingested.

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In Praise of Baptisia

Baptisia ‘Twilight’ adding height in the background, with Allium and Euphorbia

I often like to tempt you with plants which I suspect you may be unfamiliar with, but a walk about the garden convinced me to laud praise on our garden stalwarts. In particular I’d like to reacquaint you with my old perennial favorite, Baptisia, and its recent reincarnations.

Baptisia, commonly known as False Indigo or False Lupine, was one of the perennials we planted in our first garden 25 years ago, and that same B. australis, introduced as a young seedling, still surges forth each spring with vigor and good looks.  Baptisia is not a only long lived plant, it is also one of the first perennials which add height to the late spring border, shooting up to and eventually forming clumps of 3? or more. The early size factor adds greatly to it?s value. The flowers are displayed on showy spires and resemble lupines. It is a great compliment to the other late spring stars: Peonies, Iris, Euphorbia and late bulbs like Allium.

The most common species you’ll encounter is B. australis, with typically violet blue flowers and a height of 3-4′ and equal width. Other species you may commonly encounter include B. alba, (with white flowers) and B. sphaerocarpa (yellow), and to some extent B. bracteata. In recent years hybrids have been made crossing the species, alternating host and pollen plants. Ron Gardner introduced ‘Carolina Moonlight’ after  successfully crossing B. alba and B. sphaerocarpa in 2002.  Jim Ault of the Chicago Garden has developed a number of great cultivars by crossing B. australis and sphaerocarpa resulting in named forms B. ‘Solar Flare’, ‘Twilight, and Midnight Prairie Blues’. Hans Hansen has developed more crosses are becoming available such as ‘Lemon Meringue’and ‘Dutch Chocolate’.

Baptisia ‘Midnight Prairie Blues’

Baptisia ‘Solar Flare’

A form we grow in our gardens which always draws comment for it’s compact habit is Baptisia australis var minor. It forms a low 2”mound of dense blue green foliage with typical large blue violet flowers, but long after the flowers fade, B. australis var minor  shows off with its tidy appearance . Another excellent but slow growing form is a selection made by Brian Megowan of the legendary Blue Meadow Farm: B. ‘Esther’, with her white flowers born on dusky slate stems. We’re rooting stem cuttings of her now, in hopes of having young plants for sale next spring.

Baptisia australis var minor

Baptisia ‘Esther’

Some things to note. Baptisia are prairie plants and like a sunny well drained soil. Baptisia australis is the hardiest of the group, tolerating cold zone 3 winters. Baptisia alba and sphaerocarpa are hardy through zone 5. The hybrids seem to fall right in the middle with hardiness tolerance of zones 4-9. Baptisia species can be grown from seed, but her clones are vegetatively propagated. Baptisia develop deep tap roots, so division isn’t easy, although it can be done, but expect some die back and a slow recovery.