Tuesday, August 26, 2014

Hosta Heavens

You don't need to be in horticulture long before discovering certain plants that seem to naturally attract a following of enthusiasts.  Actually, this phenomenon was the subject of one of my very first blog posts.  The genus Hosta with its plethora of species, hybrids and cultivars is definitely one of those magnetic groups of plants.  Although I'm not as keen as some hosta fans, I certainly enjoy them enough to warrant spotlighting this genus as the plant of this week.

Hosta collections, like John & June's
"Hanging Hosta Gardens", showcase an
array of these versatile perennials (HHG)
What's a Hosta?
Hosta are herbaceous perennials that are currently listed as members of the lily (Liliaceae) family.  However, recent studies in cell morphology (cytology) suggests that hosta and agave are distant relatives, which has sparked the question as to whether the genus should be placed in the Agavaceae family instead.  Some sources also list hosta as in the asparagus (Asparagaceae) family.

Attractive clumps of foliage spring forth from clumps of shallow, fleshy rhizomes.  Hosta may be bred for foliage, flower, or growing requirements (particularly sun tolerance).  The sky seems to be the limit on the diversity of plants that come from some breeding programs.  Here are just a few examples.

The colors of hosta foliage ranges from a deep, waxy blue up to a pale, delicate yellow.  Leaves may be solid or they may have two or more colors.  Many varieties have a lighter margin, although some have attractive streaked foliage (H. 'Stained Glass').  Leaves may be violently linear (H. 'Hands Up') or more rounded (H. 'Blue Mouse Ears').  However, the shape is typically more attenuate, like that of a plantain.  Thus the common name "plantain lily".  Although the leaves are usually more smooth to the touch or lightly textured, there are some varieties that have deep veins that give the foliage a bubbled appearance (H. 'Crumples').  

There is also a huge variety in foliage size.  The smallest hostas fall into the 'tiny' category.  Tinys must produce leaves that are smaller than 2.5 square inches.  'Mini' hostas are one class larger than tinys.  Their leaf area should be smaller than 6 square inches, and they typically produce clumps that are between five and nine inches wide.  In practice, however, mini varieties have been known to exceed their class size depending on the environmental conditions.  On the opposite side of the spectrum are giant hostas.  'Very large' hostas should have a leaf area that is greater than 36 square inches, and the clumps may be 36 inches wide.  Wow!

Miniature hostas, like those in Jonathan
Hogarth's National collection, have leaves
that are smaller than 6 square inches (JH)
Hostas produce racemes of delicate, bell-shaped flowers that have a lovely fragrance.   Flower color is usually violet, although this ranges from deep purples to nearly white.  As is true for other plants that are bred for foliage (Heuchera) or unusual flowers (Echinacea) the fragrance may have been more or less bred out of many popular hosta varieties.  If you're looking for a fragrant hosta, be sure that feature is listed on the plant description before buying.

Many people in the industry associate hostas with shade.  There may be unfortunate consequences if some varieties are exposed to sunshine.  Blue varieties may lose their waxy covering, and some lighter groups may simply burn.  However, there are quite a few hostas out there that can hold their own in the sun.  These varieties seem to tend to have a thicker leaves that are green or lighter in color.

A brief history
Hostas native range is through northeast Asia, including Japan, Korea, and areas of China.  The evolutionary history of hosta is quite fascinating, and well worth a looking into if you're interested in learning more about the complicated past of this genus.  The ancestors of some popular new hybrids actually cling to rock faces in Japan.  You can spot the descendants by looking out for plants that have a red stem and leaves that are white underneath.  Collector June Colley informed me this white underside helped protect the plants from sun damage by reflecting light from the rock surfaces below.

Some hostas from Japan have a white
cast to the bottom of their leaves (JH)
The first Westerner to botanically describe hosta was Englebert Kaempfer as part of a survey with the Dutch East India Company.  One source provides his descriptions for the two hosta spotted on this trip as "vulgo gibbooshi Gladiolus Plantagenis folio (meaning 'the common hosta with the plantain-like leaves')" and "Gibbooshi altera (meaning 'the other hosta')".  Obviously this was a time before the Linnean style of binomial nomenclature was enforced.

When these plants were switched to the binomial system, they were renamed Aletris japonica.  Shortly thereafter in 1784, hosta were assigned the genus Hemerocallis.  If the name sounds familiar, it's because that's the genus for daylily.  Since both hosta and daylilies had a somewhat similar clumping growth habit, tufts of basal foliage that dies back in the winter, and were both in the lily family, they were considered the same genus for some time.  Although they were given their own genus Hosta in 1812, groups like the BritishHemerocallis and Hosta Society continue to celebrate both genera in one society.

Tips for growing
Annelids like slugs and snails are frequently
problematic for many hosta growers
    One things that I've noticed about plants that elicit large followings, such as orchids, dwarf conifers, and hosta, is that they all have their growing quirks.  It's certainly not always easy to grow an orchid, and the same is true of hosta.  

    The large patch of H. 'Guacamole' (or at least that's what Walmart had them labelled as in the discount bin...  I have my doubts...) that I planted under a dogwood in our front yard in Knoxville, Tennessee does fine on its own, with little maintenance or attention required.  Yet the plugs of H. 'Blue Mouse Ears' that I kept in concrete containers by the front door didn't fare so well.  

    Success will vary depending on the type of hosta and the environmental conditions.  Here are my top three for growing hosta .

    Consider displaying your hostas
    in containers.  Hanging baskets
    can give a fresh perspective on this
    familiar perennial. (HHG)
    1. Don't over-mulch!  This is true for many clumping perennials.  Although mulch is a fantastic way to conserve water and deter weed growth, too much of a good thing can be a bad thing.  Thick layers of mulch can "collar" the plant, burn the crown, promote rot, ... the list goes on.  Just remember to keep an eye out.
    2. Annihilate Annelids.  Okay, that seems a bit harsh, but slugs and snails can be extremely destructive pests on hosta -- especially in the U.K.  For example, Kew doesn't treat hostas for annelids, so the foliage of most of the specimens are tattered and full of holes.  This is just not attractive on a plant that is valued for its foliage.  There are loads of folk remedies out there, including leaving a glass of beer out, putting a copper ring around the plant, adding a ring of diatomaceous earth, etc.  Gardening is an experiment, and enthusiasts will take the time to find the right solution for their situation.   For example, avid collectors John and June interplant their collection with pokeweed (Phytolacca americana).  June is currently researching whether the saponin content of the pokeweed deters slugs and snails.  Jonathan Hogarth, another hosta fan, adds a layer of sharp rocks to the top off all his hosta containers.  "The slugs don't like to cross it," he said, "although some do get through occasionally."  Another alternative would be planting slug resistant plants.  The thicker the leaf, the more resistant the plant tends to be.  Another collector, Tennessee's own Cornelia Holland, informed me about the exciting new (relatively) slug resistant Tardiana series.
    3. Consider a Container.  I was fortunate enough to see some really spectacular hosta collections over the weekend, and all the plants were in containers!  Leaving your plants in containers gives you a bit more control over the health of your plant.  Too bright and sunny?  Just move the pot.  Need to overwinter a tender specimen?  Move the pot to the garage.  What’s more is that many hostas will naturally drape over the edge of the pot.  John and June’s collection was so full and dense that I frequently forgot that all the plants were in containers!  Placing containers at or above eye level can also give a fresh perspective.  

    Hosta heavens
    In celebration of the really fantastic collections I was able to visit this weekend, I thought I’d wrap up this week’s post with a brief list of some neat hosta gardens that I’ve come into contact with.  The list is organized in autobiographical order.

    Any Knoxvillians who have a hankering to see some massive, gigantic hostas should head to the KMA this fall before the plants go dormant.  The hostas in their courtyard are easily the biggest ones I’ve ever seen.  Definitely worth a gander.

    Jonathan Hogarth's fantastic hosta
    collection, displayed in the British style
    where the foliage is allowed to overlap
    Although I’ve never been to avid collector Cornelia Holland’s garden, I’ve heard many fantastic things about it.  As of 2012, she had 900 species in her collection, which warranted a stop on the American Hosta Society’s National Convention in 2012.  I’ve seen photos of Tranquility online and in departmental seminars at the University of Tennessee, Knoxville. A month or so ago, Dr. Susan Hamilton, the director of the UT Gardens, put me in contact with Ms. Holland to learn more about meeting her fellow hosta enthusiasts while I’m in the London area.  In no time at all she had me on track for what would be really inspiring tours.

    Next on the horizon for the UT Gardens is a world-class hosta collection, both for aesthetics and scientific discovery.  Stay tuned to their website for more information as it becomes available!

    Jonathan Hogarth’s Collection
    Mr. Hogarth not only obliged to let me come visit his miniature hosta collection, but he also planned my whole hosta day (Thanks!!!).  We almost got in a tour of His Royal Highness, Charles the Prince of Wales’ (patron of the British Hosta and Hemerocallis Society) hosta collection, but it was not to be.  My first stop was Mr. Hogarth’s for some tea and coffee, then hosta viewing.  The hostas are grown in containers all around the garden, with many growing on shelves mounted on fences.  I learned the history of the collection, loads of fun facts about the plants (a small fraction of which is contained in this post), the requirements for an official hosta collection, and got lots of inspirational ideas that I can’t wait to try at home.

    John and June of the BHHS generously opened their gardens a tour, and the display was really brilliant.  All the plants are in their own individual pots, but you wouldn’t know since the arrangements are so dense.  Although the hosta collection is at the forefront, other herbaceous perennials, annuals, and woody specimens are sprinkled in as well.  The display changes with the season.  If we had been there a month or two earlier, we would have seen a riot of Hemerocallis in bloom.  But there wasn’t a hint of daylily foliage this weekend – they’d been moved to grow on happily in a quiet, out-of-the-way location.  But one of the most interesting displays was definitely the hanging hostas.  Pots of hosta were pinned up against walls, fences, and hung from posts all over the property.  It was a totally different way of viewing hostas – from below rather than above!

    John and June's front garden includes a great deal of hostas at this time of year.  All the plants are grown in containers, and the display changes with the seasons.  Wow!
    If you have any questions, comments or suggestions, please feel welcome to leave a comment or send me an email.

    To see more photos from this week, be sure to check out the album "Hosta Heavens" on the Plante on Plants Facebook page.  "Likes", shares and comments are appreciated.

    All photos and videos were taken by Amanda Plante at the Royal Botanic Gardens, Kew unless otherwise stated in the caption.


    1 comment:

    1. The post was nice and these hostas perennials looking very beautiful. thanks for sharing informative post.