The Winter Landscape: Plant Hardiness

Plants are very specific about what soil, light and water conditions they need to thrive. Any gardener who has moved a sulking plant around 3 or 4 times before striking pay dirt understands this. It is simple to spot a plant that is unhappy.  Figuring out the cause of the trouble can be tough, as there are so many factors that come in to play. There are those plants, in defiance of every good intention and effort to find them a suitable home, that fail to prosper. I have killed outright plenty of plants. Given that every plant has a strong will to live and reproduce, those failures are frustrating and embarrassing. Figuring out what a plant needs to thrive is 2 parts science, 2 parts luck, and 6 parts good instincts. The hellebores in the above picture look unhappy, as they always do in February. They like the filtered sun, protection from wind, the friable soil and regular moisture that is available to them here in the growing season. They have what they need to thrive. What they do not like in February is the cold. Before any plant in a Michigan garden can thrive, it has to be able to survive our winters.

Plant hardiness zones indicate a worst case low temperature for different parts of the country. The USDA, in compiling data from weather stations, and factoring in mitigating circumstances which can influence low temperatures, has produced a plant hardiness map. Interested in that map making process?  mapping plant hardiness    It gives gardeners an idea of what the lowest average winter temperature can be in a given area. The hardiness map is a guide that can help gardeners select plants which are appropriate for their area. My area is at best a zone 6, and at worst, a zone 5b.  This means that plants that are able to withstand low temperatures in the -15 to -10 degrees should be able to survive in my garden. That includes these ratty looking  hellebores. Last year’s foliage may be burned from cold and wind, but they are very much alive, and waiting for some signs of spring.

The key to survival in very cold regions is dependent on that plant slowly going dormant over the metabolic slow down that we call fall, and a constant deep dormancy throughout the period of very cold weather. What the hardiness zone map does not provide for are weather events out of the norm. We have had temperatures in the 50’s and 60’s for a week. On February 18, the record high for that day of 62 degrees set in 1976 was eclipsed by a 65 degree day. One or two days of weather that warm might not affect any plants that are still dormant.  The frost is deep in the ground. But the days are staying warm. We have a low of 56 forecast for overnight tonight. Now I am starting to fret. It is too warm, way too early. Under that winter foliage, I see signs that the hellebore flower stalks have begun to emerge.

hellebore A plant breaks dormancy for a constellation of reasons.  Longer day length and warming temperatures are key. No plant reacts instantly to a brief change in conditions. But a change that persists is an invitation to wake up. Hellebores are greatly prized by gardeners everywhere. I do favor helleborus orientalis hybrids for my zone.  This group of hellebores, now known as helleborus hybridus, are bred from hellebores commonly known as Lenten roses. This group generally begins blooming in April in my zone 6 garden. Hellebore hybrids featuring the genes of Helleborus niger, commonly known as the Christmas rose, naturally bloom at a time which is winter in my garden. Do I have inter generic hellebores in my garden that would prosper better in zones further south?  Of course I do. I am always pushing my luck. I have had great success growing plants marginal to my zone. But nature is unpredictable. Nor does she care a whit for me and my love for my garden.

snowdropsOur bitter 2014 winter turned my zone 6 into a battle zone 4. None of my magnolias bloomed. My parrotias sustained extensive die back to their upper branches. My roses were killed back to within a foot of the ground plane. My clematis sputtered. My 20 year old boxwood had unbearable damage. It was a sobering experience, to say the least. Any plant marginal to my plant hardiness zone suffered damage of one sort or another. The winter of 2015 might have been worse. On February 20, 2015, the temperature in Roscommon Michigan was -39 degrees. The statewide average for that day was 18.5 degrees below zero. The damage done to evergreens these two back to back vicious winters was extensive. But those plants that were safely dormant managed to survive. The snow drops showing their faces yesterday worry me.  65 degrees in February is an anomaly.  The cold weather will return. How much cold can their flowers endure?

magnolia stellataOf course I am anxiously checking all of my early spring blooming plants.  This magnolia stellata was a 2 foot tall tree the day I bought my house twenty some years ago. It has prospered where it was planted.  It did not bloom in either 2014 or 2015. Its hardiness was sorely tested by a pair of bad winters.  The flowering in 2016 was a happening.  I am trying to decide if our warm weather is encouraging the buds to swell.  Not that I could intervene. Mother nature bats last. I am reading we have some night temperatures in early March in the teens.  Though I am ready to wash my hands of winter at the end of February, March is a winter month for us. Any early spring plant which is breaking dormancy right now may not fare so well in March. This is more a worry than a certainty.

Late this past summer, I replanted my rose garden. Though I know there is a limit to their hardiness in my zone, it is better for me to start over, than to do without. That was a personal decision, not a decision driven by a plant hardiness map. As for the dogwoods, I hope they will be able to endure a freakish warm spell in the middle of winter. No small part of the winter landscape is an appreciation for endurance.

 

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Hellebore Hardy

hellebore hardy (1)Would that every plant in my garden could be hellebore hardy. Hellebore hardy? Hellebore hardy is that state of plant being which is as tough as nails, bud and bloom hardy, every day in hostile weather, as in every crappy spring wild card day hardy. We have had crazy cold and blustery weather the first 12 days of April. As in daytime highs of 28 degrees, and some night time lows at 19 degrees.  If it were January, or February, or even the first part of March, these temperatures would not bother anything in my garden.  At that time, every plant is dormant, and oblivious to the day to day changes in temperature. This kind of cold in the spring can damage emerging flowers and leaves. Our espaliered fruit trees are very close to blooming.  I am hoping they hold off for a week, as below freezing temperatures can easily damage or wipe out those flowers. The flowering stalks of my hellebores emerged from the ground a month ago. The have been growing steadily, in spite of a lengthy bout of really cold and windy weather.

hellebore hardy (3)The flowering stalks of the hellebores usually come out of the ground in my zone in mid March. They are programmed to come out of the ground, fighting. How they fight to bloom enchants me. March and April are politely known as transitional months in Michigan.  As in 2.5 parts winter dueling fiercely with .5 parts of spring.  Hellebores bloom in spite of that conflict-  I admire that cheekiness about them. Their ability to withstand cold, snow, ice, freezing rain and wind when they have broken dormancy and begun to grow is remarkable.  All the more extraordinary is their ability to shrug off this hostile weather while in full bloom. This picture was taken at the end of the day on April 10. I was worried that every flower would be at least damaged, if not obliterated by morning.

hellebore hardy (2)It was not an idle worry. My white flowered magnolia stellata is full of white flowers gone to brown mush.  The early flowering magnolias are not hellebore hardy. Their flowering can be laid low and obliterated by cold April weather.  I don’t love them less for this.  I just know that a tumultuous spring has its disappointments, and its survivors. My stellata blooms well 2 out of 5 years.

hellebore hardy (8)The hellebores are survivors.  They do not need any help from me if the beginning of spring is deadly cold. They never ask for much of anything, actually. As for April 11, my hellebores revived. Once the snow and ice melted, and the air temperatures warmed up, my hellebores got back to the business of blooming. My old clumps are sensational this year.

hellebore hardy (12)This big clump, one of many of the old Royal Heritage strain that I grow, is unfazed by inclement weather.

hellebore hardy (5)It is hard to believe that these flowers survived night temperatures ranging from 19 to 27 degrees, over a period of almost 2 weeks.

hellebore hardy (6)Hellebore flowers are big and showy.  What is just as showy is how they handle the late winter weather. Showier still is that these plants are still growing strong, despite their age.  Most of my original group was planted well over a decade ago. I do not often see the Royal Heritage strain offered for sale – pity that.

hellebore hardy (9)To follow are some pictures of my hellebores – both old and new.  I appreciate every one of them, especially given that most of the rest of the garden is still biding its time, hoping for a clearer sign that spring is here.

hellebore hardy (7)Royal heritage strain

hellebore hardy (17)Conny is a newer variety.  This is its 3rd spring.

hellebore hardy (10)Royal Heritage strain

hellebore hardy (11)Royal heritage strain

hellebore hardy (14)Royal Heritage strain

hellebore hardy (18)This spotted double is a newer variety whose name I cannot remember. Lovely, and sparse.

hellebore hardy (16)My newest group of more recently bred hellebore hybrids are gawky and thin. I am hoping to see them put on some weight this year. It is too soon to determine whether they will form big and persistent clumps. The Royal Heritage Mix may not have the interesting shapes and the clearer colors as the newest varieties that are available, but they are reliable. Should you have an interest in this discussion regarding hellebores persistence, I would invite you to read an essay from the well known English gardener and garden writer, Noel Kingbury. His column is a regular read for me. He worries that the new cultivars are not as vigorous as the old fashioned varieties.  His life is a world away from mine, but his commentary on the garden is of interest to me.   http://noels-garden.blogspot.com/2016/02/hellebore-troubles.html

The Hellebore Festival

helleborus MerlinHellebores are the mainstay of the early spring garden in my zone. The plants themselves feature leathery foliage that may persist throughout a mild winter.  The flowers come first, on leafless stalks that emerge from the ground in late March and early April.  Once the flowers have matured, the new leaves sprout.  They range in height from 15″ to 20″, and appreciate a semi shady location in humus rich and friable soil.

helleborus corsicus IcebreakerI grow one group of hellebores in full sun, but I make sure they have sufficient water. Some clumps are going on 15 years old, and show no signs of any loss of vigor. The summer foliage is lush and glossy.  Deer don’t touch them. What appears to be the petals are actually modified leaves.  The small tubular lime green structures surrounding the center in the above picture are the actual flowers.  Those modified leaves will persist on the plant long into the summer.  This give the impression of a very long bloom time.

hellebore festivalMost hellebores are very willing to set seed. I see many seedlings surrounding my large plants this spring.  Given 3 or 4 years, they will grow on to blooming size. Some of the newer varieties of hellebores feature up or side facing flowers.  Older cultivars of helleborus orientalis feature nodding flowers.  Planting them at the top of a slope or wall will provide a better look at the flowers.  If you choose to cut them, do sear the bottom of the stem in boiling water before you condition them. They will last an amazingly long time floating in a bowl of water.

helleborus lividus Pink MarbleNew to us this year is helleborus lividus “Pink Marble”. The hellebore is shorter and more compact than most.  It grows about a foot tall, and 18″ wide.  The leaves have delicate white veins.  As this hellebore is a little more tender than most, I would plant it with some protection from winds.  A layer of leaves after the ground freezes will help protect it.

helleborus Frilly KittyFrilly Kitty features pink fully double flowers. Hellebore breeding has produced flowers in an astonishing range of colors and shapes.  It remains to be seem which will survive the test of time. Hellebores grown from seed will all be different. A hellebore selected for its flower color or vigor will be reproduced via tissue culture, which insures that all of the characteristics of the parent is repeated in the progeny.

helleborus ConnieHelleborus Spring Promise “Conny” is a white flowered hellebore with maroon spots.  The flowers are stunning.  I am sure this accounts for the fact that we are already sold out of this cultivar. It seems to be a fairly strong grower in my garden.  One clump that is year years old has a number of blooms this year.

helleborus SallySally is another member of the Spring Promise series. Spring Promise is a helleborus orientalis type, and bloom from late February into April.  They come in a wide range of forms and colors.  Sally has lovely greenish yellow flowers atop a very strong growing plant.

Helleborus IcebreakerHelleborus Icebreaker is a personal favorite.  The white flowers mature to a most beautiful shade of green.  Interested further in the green flowered types?  I wrote about them here:  green flowered hellebores  If you are not able to get by the shop today, don’t worry.  We have a great supply of many different cultivars. The best part of this year’s festival?  Mild March weather is making it possible to plant them in the ground  straight away.

 

Awash In Hellebores

helleborus.jpgI am embarrassed to complain, given what the people in Boston have endured this winter, but I will say it.  We have had a long tough winter. We had the better part of Boston’s snow last year. This year, no heart or record breaking snow, but plenty of snow nonetheless. The snow I could plow through, and shrug off. The tough part was an interminable run of very cold weather, lots of it below zero. Dressing for a trip outdoors was an event the likes of which was almost intolerable. Boots, gloves, coat, hat, and lots of layers in between. All of this piling on took lots of time. That effort did not come to much good-the cold was bone chilling.  No one took the arctic winter poorer than the corgis. Every day they would plead with me to change the channel. They were bored and irritable. It was a daily thing, wanting to be let out every possible door to the outside-in hopes one would reveal habitable weather.  The spring in Michigan does not come easy or in an orderly fashion. Mother nature takes her time, deciding when the season will change from winter to spring. We have been made to wait.

detroit garden works helleboresWe feel better about the weather, having worked to introduce our own indoor version of spring. In March, we take delivery of over 1000 hellebores from growers all over the US and Canada. We invite gardeners in our area to come, browse and review our collection, and speak for them. We mean to offer gardeners a respite the winter, with our hellebore festival. It takes a few days, but our greenhouse space is starting to look like and smell  like a garden. Our March weather seems to be moderating-we have hope we are on a track to spring.  But if the spring outdoors is practically still weeks off,  we have a version of spring in our greenhouse. Should the spring be a few weeks off, the hellebores are content to reside in  sunny window until the ground outside can be worked.hellebores_double_pink_strain__84306Hellebores are a hardy perennial in our zone. Many of them are hardy in zone 4; most of them are eminently hardy in zone 5.  I treasure them, as they are the first perennial to bloom in my garden in April.  Hellebore foliage is large, and will persist long past the fall and into the winter. In warmer zones, the foliage is evergreen. The Orientalis hybrids throw their bloom stalks very early in the spring, arising out of the declining foliage from the previous season. The new foliage which is to come after the blooming is lush and substantive. They are tolerant of a wide range of conditions in the garden. I grow them in full sun, but I water them when they need it.  They are equally as happy in a lightly shaded location. They can live and increase in a garden for many years, without any need for division. Deer do not touch them. The flowers are surprisingly large, and quite beautiful.

detroit garden works helleboresThe flowers of the hellebores my Mom grew in her garden 50 years ago did not look like these. The blooms were nodding-down facing. To enjoy her bell shaped flowers required getting down on the ground to look up into their faces. She would cut them, and put them in a vase in the kitchen window.  Her favorites were the white and green flowered hellebores, as the pink cultivars were a muddy not so appealing pink.  It took years to grow on a hellebore to a decent size, as they were only available as young starts.  There was always lots more foliage than flowers. Nonetheless, she loved the look of them in her shade/wildflower garden.  Their foliage would last the entire summer and beyond, unlike the spring bulbs and ephemeral wildflowers she cultivated. The hellebore world has changed dramatically since then.

pink flowering helleboresThis group of plants have been the subject of intense breeding all over the globe. A lot of attention has been devoted to breeding plants who flowers are out and up facing. Some breeders have produced strains of hellebores with double flowers, or unusual coloration. Marietta and Ernie O’Byrne, who own Northwest Garden Nurseries, have bred some stunning strains of hellebores.  The same can be said for Judith and Dick Tyler who own and operate Pine Knot Farms. These names are just two of a long list of hellebore enthusiasts who breed and sell plants in Belgium, Germany, England, Japan, the US and Canada.

detroit gardenworks helleboresMost of the plants in the greenhouse are hybrids of helleboris Orientalis. Helleborus Orientalis is not a species of hellebore, strictly speaking. It is a plant which is an interspecific cross from a number of different species hellebores-the O’Byrnes think maybe more than 16 species have a part in what is properly known as helleborus x hybridus. They do not come true from seed, so many of these named varieties are referred to as such and such “strain” of hellebore.  Given that the plants may take 3 years to flower, many breeders sell their young plants with pictures that show the possible color range. The advent of tissue culture has made it possible to clone specific plants, and make them available to interested gardeners.  My discussion of the history and science is quite limited-for a detailed look at hellebores, do visit the website of Plant Delights Nursery. Some of the hellebores we have came from a trip Rob made there a few weeks ago.  Tony Advent does a terrific job making great garden plants available to serious gardeners.  He also does a great job of providing an overview of the history and proper culture of the plants he sells.

   http://www.plantdelights.com/Article/Hellebore-Lenten-Rose/Hellebores/Christmas-Rose/

dscn1230The hybridizing of hellebores to produce stronger growing and beautifully flowered hellebore cultivars has been a shot heard round the world. Today, hybridizers in Europe, Canada, Japan and the US have created cultivars featuring study and garden worthy plants, and breathtaking flowers. The vast majority of the plants we have available now are cultivars that have a proven performance record. And we feature large sized plants that are old enough to produce a good crop of flowers from the start. But we also have a limited number of one of a kind plants that would appeal to a hellebore collector.

detroit garden works helleboresI did buy a collection of named hellebores last February from a nursery in British Columbia, Canada, named Fraser’s Thimble Farms.  They ship small plants to the US, bare root. I did have to pot them up, and baby them along in the window sill of my drawing studio until they took hold. I finally planted the entire lot of them in a patch in my garden that used to be occupied by some not so wonderful looking yews. Just yesterday I could see that the snow had melted, and all of those small plants look like they survived our winter. I am not expecting all of them to bloom this spring, but I have hopes.

h 5We do have gardeners come in who are not familiar with hellebores. This is not so surprising. Some nurseries are reluctant to carry plants that take 3 years to flower from seed, or are already out of bloom in May.  The good news for gardeners is what appears to be the flower is actually a modified calyx, or petal like structures that surround the actual flower. The flower is in the center, and these true petals will drop when the flowering period is over. But the calyx persist on the plants for months, giving the appearance of a really long bloom time. Still, I try to site hellebores in spots that make them easy to view in early spring.

Detroit Garden Works hellebores March 2015 (16)Hellebores also make great container plants.  Everything we ordered for our collection is in, and our Hellebore festival is slated for Friday March 20 through Sunday March 22. Can you come ahead? Of course.