Masterpiece Landscaping Blog

Nearly every year a list of new plants appear on the market  for home landscpape use.  Most disappear after only a few years on the planting schedules.    Most of these plants are perennials.  Hostas, aquilegias,  heucheras come and go like revolving doors.  Some are better than others either in hardiness, fussiness, life expectancy, disease resistance, or assets such as flower or foliage color  or strength of stems or general form.

Among shrubs, Endless Summer Hydrangea has been a big disappointment among many  landscapers for their unreliability of blueness of bloom but also frequency of bloom.   I have noticed they do not perform well in shade, even in light shade, if color and frequency of bloom are demanded.  One can follow several regimens of acidifying and fertilizing, but the blue color isn’t always reliable even when you do.  

I find the plant still useful in the shade.  The foliage is always attractive even if bloom might be scarce.

Over the past twenty years the group of plants that have made the best showings in the Minnesota northern landscape gardens are the countless new dwarf and semi dwarf coniferous evergreens.   A few of these plants were available a half a century ago, but simply not available to the general market here in the Twin City area. 

Today,  nearly every hue from blue to green to chartreuse is available in various textures, growth patterns, shapes  and sizes.   As winter comes to its end, stop by the evergreen landscape gardens at the South entrance of Courage Center in Golden Valley.   As sunlight increases, the  colors sharpen to make a beautiful display both of individual conifers as well as those in combinations. 

When you see a specimen which especially interests you, be sure you find out the accurate and complete name….the most accurate being the official Latin name of the plant….but Rhinegold Arborvitae, Gentsch Hemlock, or Motherlode Juniper would be good enough.  Most nurserymen would recognize the plant accurately. 

Do remember not every evergreen is a pine.  Most are not.   So often homeowners will ask a question similar to …”I saw a pine yesterday at the nursery and it had the most beautiful yellow foliage.  It was a creeper with real tight foliage….and… would you know the name of it?”    Knowing the color and the texture and nature of the plant is very helpful…enough in this case to know that this conifer is not going to be a pine.

By August landscape gardeners may begin to notice certain woody plants….both evergreen and deciduous… have developed a yellow look.  Yes, the foliage is decidedly not the green true to the plant’s healthier past.  What’s going on?

Unless the plant is in death mood, by which one might already notice leaf drop, what is going on ….is,  the plant is going chlorotic, meaning turning yellow due to chlorosis, the inability of the plant to take in certain nutrients.  The soil has become less acid.  The plant, one might say…or blog…is starving.

Plants typically affected are magnolias, azaleas, larch, Scot’s pine, white pine,  oak…and many, many more acid soil loving plants.  This disorder is more common on grounds with irrigation systems.  Treated city water is  alkaline.  Over a long period of time artificial watering of ones garden can exacerbate the problem.

In addition some local soils are less acid than others.  One does not have to run off to get a soil sample, only to know how to correct a local problem in the garden.

There are three soil acidifiers on the market, aluminum sulphate, ammonium sulphate, and garden sulphur.  All are somewhat different remedies to the same problem.

Ammonium sulphate is a fertilizer as well as a soil acidifier.  Ammonium tells us it provides nitrogen.   It should not be used, therefore, if one does not want to add nitrogen to a plant’s soil environment, such as in August or September when, especially young plants, might be stimulated to delay hardening off, that is, acclimating for the coming harsh season.  Landscape gardeners and others call that season, “winter”, and like our plant relatives sense it as our bleak season.

Aluminum sulphate is a granulated acidifier, usually added to a certain amount of water, and is made almost available “medicine” for the suffering plant to ingest.  If you are growing sweet corn in your landscape garden…an interesting artistic maneuver, to be sure, chlorotic plants might show color improvement in a few days.

Garden sulphur, like aluminum sulphate, is not a fertilizer.  Its effect to the soil environment is the same as aluminum sulphate, except it takes alot longer to be used by plants.  Garden sulpher is to be sprinkled onto the soil around the suffering plants and worked into the soil.  Water the area after application and then be patient.

August is a good time to cure chlorosis problems in your landscape garden.  Mature plants  may need many, many treatments.

One of the great mysteries of landscaping in Minnesota is knowing all of the elements involved which cause so-called “winter burn” on our garden coniferous evergreens.  We do know exposure to the winter sun especially in mid to late winter, the location and genus of the “victim” are all contributing factors.

We also noted that the winter of 2008-2009 was one of the worst winters for winter burn.  We noted that some yews in full sun facing south or southwest in full exposure, in front of a stucco structure showed not a millimeter of any winterburn.  We also observed many Taunton spreader yews allegedly resistant to winter burn in full shade covered with brownout  byApril first.

We concluded that there are a variety of factors which cause winter injury to  susceptible evergreen conifers, not least of which is late summer watering and plant exposure to winter wind.

With autumn soon upon us, we will be confronted with “to water? or not to water? from mid October into November until snowfall.

I never had winterburn on any evergreen for 35 years on my grounds until the winter of 2007-2008.  I owned about 25 yews displayed one place or another in my landscape. My irrigation system is usually turned off around October 24th.  I was alarmed for yews when well grown and groomed are elegant shrubs or trees.  Most are located under some canopy of deciduous tree, just shady enough, I felt, to warrant confidence my plants were safe from winterburn…as they appeared to be for 33 years.

Last autumn as an experiment, I decided to stop irrigating the garden three weeks earlier, thinking I had allowed these yews to go into winter without sufficiently acclimating to the harsher temperatures and the winter environment in general.  I lost nearly 200 years of yew plant growth on my property, including a tree 25 feet tall.  Many lost were located in deep shade.

There have been some professional studies regarding winter burn on conifers in general, but information from them has been contradictory.  Some encourage watering regularly until snowfall.  Others recommend easing off on watering gradually in order “to toughen” the plants up.

On one point studies recommend…do not, as a rule, fertilize coniferous evergreens after  August 1.  Encouraging new growth on the plants delays “hardening” them off for the cold season.

The garden season this year, 2009, in the Twin Cities metropolitan area has been one of the driest and coolest in recorded history.  As a generalization we can predict that signs of autumn will arrive earlier and the coming winter will be earlier,  longer, and probably snowier.

The observing home owner will notice that foliage toward the  interior of  pines, arborvitae, junipers, especially and in general, of all evergreen conifers in our climate will begin to turn yellow.  Folks become alarmed thinking some disease has infested their evergreens.

In fact, however, there is nothing to worry about, for nature is doing nature’s thing.  These evergreen conifers are simply shedding the oldest needles of their crop as they do every autumn.  It is as predictable as a sugar maple or any other deciduous shade tree shedding all of its leaves at the end of each growing season.  We usually expect this ritual of nature in October, after all, that’s why we own leaf rakes.

Most Minnesota home owners call all coniferous evergreens “pines”.  My pine this and my pine is doing that…..even though the evergreen tree might not be a pine at all, but an arborvitae, or a spruce, a chamaecyparis, or yew, here a juniper or there a fir or hemlock.   Not all Minnesota evergreens are equal!

There are many “fish” in the Minnesota evergreen pond.  Most are easily distinguished one from another.

We at Masterpiece Landscaping  would like to invite interested home owners to learn more about these “pines” and their care, by offering a two hour session at our gardened grounds in Minnetonka tentatively scheduled for Saturday, August 29, at 9:30 AM.  Attendance limited to 20.  Call us at 952 933 5777 for further information.  There will be no admission charge.

Over the past four or five days I have noticed in my own garden dozens of perennials from a wide group of genera showing the same foliar disease symptoms; countless dark spots on leaves slightly to severely curled and in some cases the plants appear to have blackened leaves severely curled and falling from the plants almost denuding it.  Similar symptoms are also showing on my Black lace elderberry…

I don’t own a microscope or anyother instrument to guarantee accuracy of diagnosis, but I offer the following as a general rule:  If the same symptoms ravage a wide variety of plants of different genera, the disease agent is probably  bacterial, rather than fungal or viral.

A minority of my diseased plants are recently showing recovery, that is, the new foliage appears healthy, free of infection.  So from that I suspect the frequent rains we had for most days of  more than two weeks in succession, caused the bacteria to develop and spread, and it did so quickly.  With the drier conditions returning,  the suspected bacteria no longer can thrive without a reliable continuing presence of moisture.  I shall have to wait to know if some of the plants more severely diseased ( Angelica, Ligularia, Sambucus, Geranium) will recover.

Fungi generally infect plants within a genus or family and are unable to cause such havoc to such a wide variety of  unrelated deciduous broadleaf plants.

I have lived at my present property for 35 years.  Until the winter of 2007-08 none of the evergreens on my property suffered from the dreaded winter burn on evergreens.

Evergreens most susceptible to this malady are yews, certain junipers, and arborvitae.  Symptoms show damaged foliage on the south and/or southwest side of the plant above the snow line.  In some cases nearly the entire plant is browned out.

The cause is usually blamed on the sun and snow, ie,  as the sunlight in February and March becomes more direct, the foliage on the south-southwest exposure warms up on a very sunny, very still day,  activating exposed tissue even though the outdoor temperature might be zero degrees.  When the sun sets or disappears behind some structure, the activated cells are destroyed as the temperature drops below freezing.

There is a debate whether watering these susceptible evergreens well into November in our Minnesota climate adds to the problem due to the fact the plant does not “harden off” ( sufficiently adapted) to the tortures of Minesota winters.  Others believe the lack of continued autumn watering makes yews and arborvitaes more likely to winter burn.

This past winter was exceptionally damaging to many, many evergreens.  I lost five mature yews, one a 20 foor tree and the rest 30 year olds of significant girth and my grounds are quite shaded by mature deciduous trees.  All but one might have recovered, but it would have taken years before the extensive damage  would have been  masked.  Many large Mint Julep junipers were also severely damaged.   This spring  newly planted hemlocks looked pathetic whereever they were planted.

I also had invested heavily in purchasing my first hindu-pan stylized pruned Scots Pine.  Josh Perlich of the company installed a beautiful slate arrangement to feature the hindu-pan sculpture in a very private “closet”  setting along a main garden path.

To remind all who love garden settings, Nature has its own designs regarding the life span of living things.  To add more injury to this once lovely hindu pan Scot’s pine setting, a 30 year old yew commanding the privacy, died from winter injury ruining the entire picture.

Although this past winter would measure high for normal winter burn, there must have been another factor in action.  I, as well as several of our clients, believe the winter was a windy one, especially when in January or February there were below zero temperatures over a weekend with winds over 20 mph.

For those of you new to landscape gardening, you may come to enjoy your grounds more by recording certain seasonal peculiarities of weather, or times of blooming or leaf fall to help you take steps to keep your plantings happier and more beautiful in the future.   glenn h ray