Mark has been the Director of Horticulture at Rotary Botanical Gardens in Janesville, WI for the last 14 years. Along with dedicated staff and volunteers, Mark coordinates the development and improvement of this 20-acre botanical showcase. Mark’s background is in landscape architecture and urban forestry although his true passion is obtaining, growing, observing and photographing all manner of plants.
 

 

The Truth About False Forget-Me-Nots
by Mark Dwyer - posted 04/20/12

 

Each spring I'm more and more impressed with the perennial false-forget-me-nots (Brunnera macrophylla) out in the garden.  Also called Siberian bugloss, this hardy perennia (zone 3) is native to Eastern Europe and has very few insect or disease problems and is quite low maintenance.  This garden stalwart prefers moist, well-drained soils in partially shaded locations or dappled woodlands where it can thrive.  All varieties will typically get 12-15" tall and will form a clump 18" wide or so.  This species is also quite drought tolerant once established and will give many long years of service.  While the heart-shaped leaves are the primary interest for many of the cultivated varieties, the early spring flowers are not without interest.  The showy electric blue flower clusters (see above) are very reminiscent of forget-me-nots (Myosotis) and are quite interesting for about two weeks in late April and early May.  While I love that flower show and it should never be underestimated, the foliage is what really steals the show.  There are many varieties that have significantly different foliage from the "straight" species which is green-leaved and quite uninteresting after the spring blooms fade.  One of the most popular varieties is 'Jack Frost' (see to the right) which is the Perennial Plant of the Year (chosen by members of the  Perennial Plant Association or PPA) for 2012 and in my mind, is very deserving.  In the past, the variety 'Langtrees' was popular for its silver spotting between the veins.  It's merit was for offering "illumination" in the shaded garden.  The shade garden  becomes so much more reliant on foliage as flowers become more challenging to provide throughout the length of the growing season.  Brunneras are great partners with plantain lily (Hosta), barrenworts (Epimedium), lungworts (Pulmonaria), ferns and other shade tolerant perennials.  There have been so many other awesome introductions over the year and we display about a dozen varieties at Rotary Botanical Gardens. The variety 'Mr. Morse' is known for not only silvery leaves but white spring flowers   Another nice variety that has almost pure silver leaves is 'Looking Glass' which provides that superior "illumination" in the shade.  See this variety below.  The variety 'King's Ransom' (see to the left), offers a nice variegation like 'Jack Frost' but with yellowish edges and highlights that fade to a cream in summer.  The yellowing of this variety does not look "sickly" at all and is a nice accent.  There is now a golden-leaved variety called 'Diane's Gold' (originating from Madison, WI) with chartreusy-gold leaves which I think looks best (and brightest) in spring and fall as it fades a bit in our summer heat.  Regardless of your variety selection, see the truth about these wonderful false-forget-me-nots and see where they can be of the most effectiveness in your garden.  heat 

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It’s Time To Share Your Donuts
by Mark Dwyer - posted 04/05/12

 

With perennials quickly emerging with the warming soil and early start to spring, it's a great time to evaluate your plants for division needs.  While many plants, like peonies (Paeonia) and hellebores (Helleborus), don't need division for many years, many other perennials do benefit from being divided every three to five years.  Many plants will consistently expand with age, thereby having the most vigorous growth on the outer radius of the plant.  The original center of the plant then becomes the oldest portion and frequently the least vigorous area as well.  Some perennials, like those seen here, will then vacate the old center of the plant and focus energy on this outer ring.  Perennials with this "donut-like" appearance are prime for division and spring is a great time to slice, dice and relocate portions of the parent plant.  Keep in mind that while most perennials can be successfully divided in spring, while some others prefer division later in the season.  A good example would be bearded (Iris germanica).  If left to grow, these "halo" perennials do visually fill in the center of the plant but in the case of ornamental grasses, this effect can create a floppy display with an apparent gap in the center.  The grass shown in the upper left of this blog is the perennial feather reed grass (Calamagrostis x acutiflora 'Karl Foerster') that has a great upright form in the landscape.  However, this grass creates "the donut" within five years of division and is an easy grass to divide as needed.  Division with a sharp spade is done quite easily.  Keep in mind that some of the larger ornamental grasses like maiden grass (Miscanthus), switch grass (Panicum), Indian grass (Sorghastrum), etc. may require significant efforts for proper division.  This sometimes necessitates digging out the entire grass and cutting it in to chunks with a hand saw or chain saw (I've seen it done!).  The other photos here are of hostas that exhibit this same growing pattern in time.  The hostas do fill in nicely though but this time of year is ideal for some aggressive division attention.  You actually can recolonize the "dead" centers of the "donut" perennials.  It's recommended that you amend the soil with compost or other organic matter after loosening that soil up; Keep an eye out for the "donuts" in your landscape and address them accordingly as the timing is perfect right now.

 

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Don’t Be Bereft Of Barrenworts!
by Mark Dwyer - posted 04/01/12

Greetings all!  I'm happy to be joining the blogging team for the Wisconsin Gardening magazine and wish you the best success with your own garden.  With our warmer than usual spring, many plants are emerging and blooming early this year.  Take the time to get outside and enjoy the early color contributions of your spring bulbs and note the subtle color and form of some of our most exquisite of the first blossoms.  Some of my favorite early bloomers include the barrenworts (Epimedium sp.) as they not only offer great early flower color but a top notch foliage texture as well.  Also called bishop's hat or fairy wings, this hardy perennial is native to portions of Europe and Asia and is a stalwart perennial in shadier locations.  At Rotary Botanical Gardens, we display over 50 varieties of barrenworts and have found them to be not only hardy but very low maintenance in a wide range of lighting and/or soil conditions.  This perennial, after offering nice spring blooms amongst the emerging foliage, may additionally have some reddish spring tinting to the leathery leaves.  Many varieties and species are also noteworthy for showy fall foliage colors including yellow, orange, red and deep maroon.  The fall color may come late in November but is no less showy.  Barrenworts, while mostly clumping plants, are an effective ground cover when planted in larger groupings.  However, they are also great neighbors for hostas, lungworts (Pulmonaria), hellebores (Helleborus), false forget-me-not (Brunnera) and ferns.  Preferring moist but well-drained soils, this long-lived plant is also quite drought tolerant once established and rarely shows any insect or disease problems.  Select them not only for their showy spring blossoms but their solid foliar performance from spring thru fall.  Directly below are the flowers of Epimedum x rubrum (red barrenwort) and the tinted spring foliage as well (second photo down).  The next photo shows the white and yellow blooms of Epimedium x versicolor 'Sulphureum' which is one of the more commonly available varieties.  Note the late fall colorFurther below are the blooms of Epimedium grandiflorum 'Lilafee' or 'Lilac Fairy' which has few rivals for showiness!  At the bottom is an extreme close-up of Epimedium sempervirens 'Mars' which certainly looks "otherwordly".  Note the superior fall color of that variety in the bottom photo. The shadier garden, when bereft of barrenworts, will only benefit from their durable and showy involvement!

 

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