The North American Japanese Gardens Association (NAJGA) is holding a regional event at Cranbrook Gardens in Bloomfield Hills, Michigan on May 17-19, 2018. This event—”Creation & Rejuvenation: Six Japanese-Style Gardens in Michigan”—brings together garden professionals and hobbyists to explore the challenges and benefits of Japanese gardens in the Midwest using six case studies. Garden tours include the Cranbrook Japanese Garden, Freer House, McGregor Reflecting Pool and Sculpture Gardens, Kathleen and Milton Muelder Japanese Garden, Shigematsu Memorial Garden, The Richard & Helen DeVos Japanese Garden, and Frederik Meijer Gardens and Sculpture Park. Click here for more information.
Many people in Michigan have noticed the yellowing and thin appearance of white pines that have stood sentinel and provided shade for decades. Some who didn’t recognize those earlier symptoms will see the first sign of this region-wide white pine problem as a dead tree.
What horticultural professionals have noticed in the Midwest, including southern lower Michigan and some areas further north on the mitten, is best described as white pine decline.
Decline is reduced vigor, below-normal functioning and slower growth in a tree when those symptoms can’t be attributed to a specific disease or insect. Trees in decline may fall prey to insect or disease problems because they are weak, but those are additional complications rather than causes of decline.
A tree may decline for many years. If its situation doesn’t improve, it may exhaust its lifetime starch reserves and begin to exhibit dieback—which looks just like it sounds and often ends in death.
I first noticed white pine decline in the mid 1990s. Many white pines yellowed suddenly, alarmingly and at least one 40-year-old tree on a property I garden died. Based on the positions of the most afflicted trees relative to northwest winds and open ground, and a severe winter that had just passed, I attributed the problems to cold-related root damage. Others came to the same conclusion and experience since then seems to support this.
Do you remember February, 1996? The white pines do! On the night of February 2-3, temperatures from the Great Plains to New England dropped to lows never seen before or not seen for 40 years. That week, the outbreak of Arctic air set nearly 400 record daily minimums and at least 15 all-time lows in the eastern U.S. Wind chills of -50 and -100 degrees were common.
In southeast Michigan, the mercury plummeted 15 to 20 degrees in just a few hours on a night when there was not even a trace of snow to insulate the soil. Branches and trunks of some plants died, and the frost knifing suddenly and deeply into the unprotected soil killed roots even on hardy, established plants.
By spring, gardeners would be mourning the loss or severe damage of thousands of decades-old Japanese maples, and finding privet hedges, rose of Sharon shrubs and even stalwarts such as old junipers dead or killed to the ground. Plants hurt but not killed would begin the slow process of regenerating roots and limbs only to be socked with drought years, one after another.
Shallow-rooted plants like white pine may have been worst hit. Left with fewer roots than they should have, they were not likely to take up enough water and nutrients to fuel regrowth. They were in trouble even if drought had not begun to compound the loss.
Six years later, my tally sheet of all the white pines I see regularly in my travels and those I tend reads this way: Some of the first-affected died and many are still struggling. Some which did not initially show symptoms developed them during subsequent drought years. Only a few recovered. Very few escaped all damage.
In its bulletin, “Decline of White Pine in Indiana,” Purdue University Cooperative Extension reported, “white pine decline… has been a problem for many landscapes in Indiana. …Declining trees usually look a pale green, or even yellowish, compared to healthy trees. Needles are often shorter than normal; sometimes the tips of needles turn brown. Needles from a previous season often drop prematurely, giving the tree a tufted appearance.
“With loss of needles, the tree has a reduced ability to produce the energy it needs to survive…
“With severe or compounding stress factors, the tree may gradually decline and eventually die. Decline may be gradual or rapid, depending on the number and severity of stress factors.”
University of Missouri Extension made similar reports like this one from August, 1999: “We have received many white pine samples into the Extension Plant Diagnostic Clinic this year… from mature white pines, about 20 to 30 years old that are in a state of decline. …Other Midwestern clinics have also seen (this) and have been unable to explain most cases of decline…”
“We therefore believe… that the problems we are seeing with white pine may be related to environmental factors and site conditions… such as heat, stress, drought, flooding and sudden extremes in temperature and moisture.”
Note that experts don’t lay full blame on the cold but on a combination of causes. Ironically, reliable cold and snowier winters may have worked in some trees’ favor.
Missouri, Indiana, Ohio and the southeasternmost part of Michigan, which have all seen many white pine problems since the 1996 freeze and subsequent droughts, are south of white pine’s native range. Since a species’ native range is delineated at least in part by climate, we know that something about the weather in our area is probably not optimal for white pine. A record-breaking warm-up that came after the 1996 cold snap may be one of the climatological events these trees can’t handle. Two weeks after the freeze, all across the area affected by decline, temperatures jumped into the 70s, 80s and 90s. For the most part, white pines growing where there was the usual reliable snow-cover or where the warmest air didn’t reach, fared better.
What happened to the white pines was outside current experience, on a scale so broad that few had the perspective to be able to recognize it. Now that we look back and know how long a tree has been declining which we just noticed this year, we can wish we knew more earlier, but it won’t get us anywhere.
So if you have a troubled white pine, have it inspected by an arborist. Rule out disease and insect problems. Give it the help it needs to fight any secondary problems. Do what you can to alleviate underlying stresses.
Establish a regular watering routine and fertilize the tree in early spring to see if it responds. Aerate the soil if it’s compacted. Be pleased if the tree reacts positively, but be realistic about its chances and your needs. Many of these trees are years past their point of no return. Even those which respond positively to treatment may take many years to recover.
Article by Janet Macunovich and photos by Steven Nikkila, www.gardenatoz.com.
by Keith Alexander
“April showers bring May flowers”—we’ve all praised the coming of spring with this cheerful rhyme. After the cold, dreary days of winter, it’s here… Spring! This is a great time to plant shrubs so they can begin to establish themselves before the long, hot days ahead. It is best to plant flowering shrubs before they leaf out in the spring. That said, with the proper care and watering, they can be planted at any time. I have put together a list of some of my favorite shrubs. By no means exhaustive, this list is a great starting point for some colorful ideas.
‘William Penn’ Barberry
This dwarf, dense, semi-evergreen plant (Berberis x gladwynensis ‘William Penn’) will grow 4 feet tall and 4 feet wide over 5 or 6 years. In May, tiny, bright yellow flowers will cover the waxy bronze-green foliage that looks much like holly. In the fall, these 1- to 2-inch narrow leaves turn a beautiful bronze color and remain on until spring. In a mild winter, this zone 5/6 plant will bounce right back to bright green. If the winter was a tough one, sometimes the branches that were above the snow may die back to the snowline or the center of the plant. Though this barberry is sometimes hard to find in garden centers, it’s worth looking for. Remember to plant it in a sunny location out of the west winter wind. This plant will do well in almost any well-drained location.
‘Dark Knight’ Bluebeard
This summer-flowering shrub (Caryopteris x clandonensis ’Dark Knight’) enjoys a sunny location in almost any type of soil. Rich green foliage gives way to beautiful purple/blue flowers that begin in June and continue for almost a month. A compact bluebeard, it only grows to 2 or 3 feet tall. It is best to cut this deciduous shrub to the ground each spring for maximum beauty, form and flower. It is resistant to most pests and disease.
Variegated Rock Cotoneaster
This slow, diminutive garden plant (Cotoneaster horizontalis `Variegatus’) is a graceful addition to any landscape, particularly a small space or rock garden. Its tiny, 1/4-inch white and green leaves turn burgundy before dropping each fall. A delicate coating of tiny pink blooms turn into shiny red fruits in late summer. Grows in a partial shade to sun location. This colorful character grows to 24 inches in 5 to 6 years.
‘Miss Kim’ Dwarf Korean Lilac
This compact-growing lilac (Syringa patula ‘Miss Kim’) gets only 3 or 4 feet tall. A reliable lavender bloomer each May, this fragrant lilac needs a well-drained sunny location for best performance. Sometimes found as a dwarf tree or top-grafted form, this lilac makes an excellent accent feature. It has beautiful medium-sized leaves that turn to a burgundy tint in the fall.
One of the most outstanding lilacs available, this French hybrid form (Syringa vulgaris ‘Sensation’) boasts showy purple/red florets edged in white each spring. An upright grower, following the tradition of most other French lilacs, it can grow up to 10 or 12 feet tall. This fragrant lilac should be used in a sunny location where it has room to grow.
The group of plants that include potentilla is a large one, and this can make choosing the right potentilla a difficult task. ‘Abbotswood’ (Potentilla fruticosa ’Abbotswood’) is one of the best white-flowering forms of potentilla. It grows 2 to 3 feet high, with delicate blue-green leaves. A generous covering of white blooms decorate this dense shrub each spring. If the plant is pruned after it blooms in spring, a second crop of blooms will be your reward. This hardy shrub looks for a sunny location in any type of soil or exposure.
‘Gold Star’ Potentilla
Of the yellow potentillas, this one (Potentilla fruticosa ’Gold Star’) has a lower habit and larger, showy yellow blooms than most. Its growth should stay under 24 inches. Yellow flowers 2 inches wide will cover the plant throughout the summer if the spent blooms are pruned off. Once again, a sunny location is best for this and all other potentillas.
‘Red Ace’ Potentilla
Growing in a dense mound to 30 inches, this summer bloomer (Potentilla fruticosa ’Red Ace’) is coated with unique flame red, 1-inch flowers that are pale yellow on the undersides of the petals. This re-bloomer will change flower color from flame red to yellow based the intensity of the heat and moisture conditions surrounding this zone 3 hardy grower.
‘Royal Purple’ Smoke Bush
This large shrub (Cotinus coggygria ’Royal Purple’) grows to 15 feet tall. Its intense purple leaves are nearly 4 inches across. A delicate frosting of yellow blooms covers this plant during early summer, giving way to pink/purple seed heads. These long-lasting airy clusters cover the tree for weeks, giving the impression of a cloud of smoke. Plant this fast grower in a sunny location that allows for room to spread. Best planted in well-drained soil out of direct winter winds.
‘Alpina’ Japanese Spirea
A very dense mounding shrub (Spiraea japonica ‘Alpina’), this zone 4 summer bloomer makes a great accent plant in today’s modern, low maintenance landscape. Delicate pink clusters of bloom will cover this plant all summer long. Although there are many different spireas to choose from, this one rates high as one of the best dwarf, green-leafed forms. Almost any sunny location will be great for this 18-inch tall plant.
Limemound Dwarf Spirea
This brightly-colored, mounding plant (Spirea x bumalda Limemound) makes a dramatic accent plant for any landscape. A good choice for massing, this 24-inch tall plant has delicate pink blooms on and off all summer long. The most dramatic color comes from its orange and lemon-yellow leaves in spring that turn to lime-green throughout the summer. It finishes out the season with beautiful auburn-red foliage in the fall. Hardy to zone 3, this sun-loving plant will tolerate almost any type of location.
‘Sunburst’ St. John’s Wort
This upright hardy shrub (Hypericum frondosum ’Sunburst’) makes a great border, accent, or hedge plant. Its dense habit, and dense blue-green 1/2-inch leaves make an excellent background for the profuse yellow blooms that cover the plant throughout the summer. A zone 4 rating makes this one a hardy choice for almost any sunny location.
A medium grower to 6 feet, this viburnum (Viburnum carlesii) is one of the most fragrant available. Leathery green, 3-inch leaves are soon followed by 4- to 5-inch snowballs of pink/white fragrant blooms each spring. Following the blooms, small red fruits hold on until they turn black in the fall. These black berries are highly desired by the most discriminating of our feathered friends. This classic plant will do well in partial shade or full sun, and is hardy in almost any location.
‘Pink Dawn’ Viburnum
Large, dark green foliage covers this upright grower (Viburnum x bodnantense ‘Pink Dawn’) to 8 or 10 feet. Very unique rose-colored blooms may open as early as February if the weather is mild. Its blooms are fragrant and hardy. Small, dark blue fruits will form in late spring. These small unobtrusive fruits make great attractions for the birds.
‘Shasta’ (Viburnum plicatum f. tomentosum ‘Shasta’) is an improvement on the traditional Japanese snowball viburnum. It has a compact habit that grows only to 6 or 8 feet. Showy white blooms coat the horizontal arching limbs, creating a dramatic effect in May. Its large, 5-inch leathery green leaves turn to a reddish purple color in the fall. The red fruits turn to black before the birds begin to feed. ‘Shasta’ makes a great border or screening plant in almost any type of location from medium shade to full sun.