Rime and Reason

This weekend I got to take a leisurely drive to the northern end of Michigan’s Upper Peninsula with my daughter so she could check out Michigan Tech University.  Lots to see along the 488 mile drive from DeWitt to Houghton, including a moose, lots of snowmobiles, and the world famous ‘Yooper tourist trap’.  (For the uninitiated, people that live in the U.P. are known as Yooper’s, while those of us that live beneath the Mackinac Bridge are known as ‘Trolls’)  Once we got along the Lake Superior side of the U.P. we drove through a short section of freezing fog that produced rime on the surrounding forest.  Our tight schedule and road conditions prevented me from stopping to get photos but I found several on Wikimedia commons that illustrate the phenomenon.




Here’s a recent TV weather blog that provides some additional photos and information rime and hoar frost, which is a related winter weather phenomenon.  Rime forms when air temperatures are below freezing drop below the dew point as the water condenses and freezes, the ice crystals accumulate on the windward side of trees, fences, and other objects.  Another similar phenomenon is hoar frost.  Hoar frost looks similar to rime but is lighter and not associated with freezing fog.  It forms when surfaces cool below the dew point and ice crystals accumulate.  Here are some examples of hoar frost we experienced a couple years ago here at MSU.

The Winter Weekend Garden Warrior

As Garden Professors, we are very careful regarding product endorsements. Actually, much energy is spent trying to bring to light weird/crappy/useless/money-wasting gardening products.

But when we feel strongly about the usefulness, quality, and utility of a product, it is our duty to pass that information along as well.

I didn’t mean to be a walking advertisement last weekend.

We were in the final throes of getting our garden cut back; Joel was laughing that I “needed another set of hands” when I came around the corner.  “Not with my fabulous Firehose Work Pants from Duluth Trading Company, I don’t!”  Thus the inspiration for this post.

All products noted are, variously: warm, waterproof, full of pockets, sharp, indestructible, dependable, and/or delicious.

Selection and Protection: Preventing the heartbreak of splayage

We’ve had considerable discussion over on the FaceBook site concerning snow damage to columnar arborvitae.  This is a common phenomenon resulting in a condition Holly has dubbed ‘splayage’.


The question, of course, is what to do about it?  My standard response to addressing most problems related to winter injury is there are two options: selection and protection.


Selection means putting the right plant in the right place.  For columnar arbs this means not planting them in areas prone to wet heavy snow.   Here in mid-Michigan we get a wet snow about once every other year.  Last winter we had a 10” of snow in Nov. 30 that resulted in a lot of tree breakage, including arbs.  The problem is the branch structure of columnar cultivars such as ‘Holmstrup’ or ‘DeGroots spire’ cannot bear up to the snow weight.  Remember these are cultivars that were specifically selected for their upright branch habit, this is not the natural branch pattern of the species (Thuju occidentalis or Thuja plicta depending on the cultivar).  There are, however, some narrow trees that are adapted to sloughing off heavy snow.  For example, most forms of Alaska false cypress (Cupressus nootkatensis) will do well under heavy snow loads.  Also, weeping white spruce (Picea gluaca ‘Pendula’) is a good narrow conifer for snowy locations.


Alaska falsecypress (right) is adapted to heavy snow. Notice how snow hangs on other conifers on the left.

But what do you do if you already have a row of columnar arbs and you live in an area prone to heavy snow? Protecting trees from bending over by tying up the upper 1/3 is often the only reliable option.  Note that the all ties or wrap need to be removed in the spring.  Yes, it’s a lot of work.  Makes the ‘right tree right place’ thing sound better.  Note that you only need to provide enough support to keep the branches together, you don’t need to wrap the entire tree like a mummy.


I want my mummy…  Does this work?  Probably.  Question is do you want to look at it all winter?

What about repairing damage after trees have splayed?  Some arborists I’ve talked to about this problem have had success tying up tops after the fact provided the trees are tied before any new growth occurs and the branches are bent, not broken.  It is important to remember that this  is similar to situation with standing and  guying up trees after a windthrow event.  Yes, you can stand the tree back up but how are you going to stop it from happening again?  In the case of splayage, you’re into a cycle of tying or wrapping every year.

The winter of our discontent

I was in the field today at our Southwest Michigan Research and Extension Center (SWMREC) so just a quick post and a couple of pictures.  Today is the last official day of winter but you’d never know to look outside. Our current temperature in East Lansing is 78 deg. F.  Our late winter warm up has officially reached historic proportions as we have blown by 1945 as the warmest winter in record in lower Michigan.  To give you an idea of how messed up things are the current temperature in Minneapolis, MN (77 deg.) is 21 deg. warmer than Los Angeles (56 deg.). 

While I hate the be the messenger of doom as Chicagoans enjoy fun and frolic at the beach, for many segments of horticulture what we’re watching unfold is a slow motion disaster.  Phenological development (bud-break, flowering etc.) is currently running almost a full month ahead.  Many important fruit crops such as plums and peaches have started to flower and the rest aren’t far behind.  Based on long-term records it is virtually certain that we will have several hard freezes before the weather warms up for good, meaning that many of these crops will be severely damaged if not destroyed entirely. So, if you’re in the Midwest or East, make the best of the good weather but recognize all good things must come to an end…

Plum crazy.  Plum blossoms at MSU SMREC, March 19, 2012

Just peachy.  Peach tree in bloom. MSU SWMREC, March 19, 2012.

Winter winners podcast

I got so excited about our live tree hunt (posted yesterday) that I forgot to put up the podcast!  So here it is…Winter Winners.

The interview of the week is at the Washington Park Arboretum in Seattle, with Director Dr. Sarah Reichard.  We visited the Winter Garden, where she (wearing her taxonomy hat) picked out her favorite plants.  They include paperbark maple (Acer griseum)…

(the sun shining through the bark is incredible)

…and contorted hazelnut (Corylus contorta)…

(hard to see, but love the bare twigs)

…and Garrya x issaquahensis

Sierra Exif JPEG
(these most amazing catkins get longer and longer)

…and Rhododendron strigillosum with the coolest bristly petioles:

(a very tidy rhododendron)

As always, I would love questions and suggestions for future podcasts!

Who you gonna call?

As I noted last week, this has been a long winter in Michigan – OK, Jeff, no chortling from the frozen tundra of Minnesota…  Most gardeners in this area have only been able to do their spring yard and garden clean-ups in fits and starts as the weather allows.  We’re finally warming up a bit this week but now strong storms are in the forecast.  One of the things gardeners will want to do is to size up any winter damage that has occurred since they put things to bed last fall.  Although our winter was long, it was otherwise unremarkable with few temperature extremes – low or high – that would likely cause problems.  In fact, aside from some heavy snow in February, the winter of 2010-11 was probably the closest thing we’ve had to a ‘normal’ winter in the 11 years I’ve lived in Michigan.  Nevertheless, we will still be taking numerous extension calls on what we would consider ‘typical’ winter damage to trees and shrubs.

In this neighborhood not too far from my house, deer have declared open season on arborvitae.

One of the biggest issues we face is wildlife damage.  The two biggest sources of problems are small mammals and deer. Small mammals such as mice, rabbits, squirrels and voles cause damage mainly by gnawing on trunks and branches.  Despite their small size, these animals can kill trees by removing bark and underlying tissue around the circumference of a tree trunk, a process referred to as ‘girdling’.  If a large portion of trunk circumference has been girdled, trees are unable to move energy reserves between roots and shoots, and will eventually die.  Deer can cause extensive damage to trees and shrubs due to feeding and also through rubbing their antlers.  Deer feeding is often indicated by a ‘browse line’ based on how high deer can reach.   Rub damage from deer antlers can cause major deformation to trunks and can even kill trees by girdling.  I was in a new subdivision in the East Lansing area this weekend and well over half of the trees on the tree lawns will need to be replaced due to extensive deer rub damage.

At least half of the trees in this entire subdivision will need to be replaced due to deer-rub damage.

Dealing with wildlife damage is a complex issue and varies with local conditions and wildlife pressure.  Fortunately, wildlife experts from several universities (Cornell, Clemson, Nebraska, Utah State) have organized the Internet Center for Wildlife Damage Management. http://icwdm.org/  This site is one of the best resources I have run across for assessing and dealing with wildlife damage issues.  If you’re in a position where you have to deal with wildlife damage or advise clients about damage, this is a useful site to add to your bookmarks.

Cold enough for ya?

Like many people we spent the past couple days digging out from the massive snowstorm that swept across a large swath of the country.  This was definitely a made-for-TV-weather event as national and local TV weatherfolks took up their positions and gave us breathless live-remotes of the “Blizzard of 2011”.

40 mph wind + 1 little crack = a barn full of snow.

Almost as predictable as video footage of snow-ploughs on the streets and locals snow-blowing sidewalks; climate change skeptics are using the recent round of winter weather as proof that global warming is a hoax and that there’s really nothing to worry about except the economics of ‘cap and trade’.  Just google “climate change skeptics blizzard” and you’ll get the idea.

Bob and Quincy were unfazed by the sub-zero wind-chills.

The problem, of course, is that climate patterns don’t move in a strictly linear trajectory and looking at one extreme event doesn’t prove anything one way or the other.  Even looking a few years time sequence may not present the full picture.  Deroy Murdock used the illustration below to argue in the National Review Online that there is no link between rising CO2 and increasing temperatures.



But looking at a broader timescale tells a different story.  While there are year to year fluctuations a clearer association between rising CO2 and global temperature begins to emerge.

The figure above was taken from an article by Stamhoff et al. 2007, “Recent Climate Observations Compared to Projections” (Science 316 (4): 709).  The dashed lines represent the ranges predicted by a major climate model starting in 1990 – the solid line represents what actually happened.  As shown in the figure, climate models have been fairly accurate overall and, if anything, have been conservative in predicting climate change; especially with regard to changes in sea level.


So where am I going with this? There are certainly enough climate change debate/Al Gore bashing blogs out there to go around and I don’t want to devolve entirely into that debate, but the simplistic ‘exception proves the rule’ mentality of the skeptics gets a little tiresome.  I remember hearing my first talk on global warming at a forest biology conference in the mid-1980’s.  The main point that stuck with me then was that increasing global CO2 would not necessarily result in warming every year but that we would see an increase in the frequency and severity of extreme climatic events; droughts, hurricanes, floods, and yes, even blizzards.  Even some of the earliest discussions on climate change in the early 1980’s (e.g., Manabe and Stoufer 1980) recognized complex feedbacks in the global climate system that would result in some regions getting wetter while others suffered drought.  So while the skeptics may use this weeks’ blizzard as evidence against climate change, increasing frequency of severe weather actually argues for it.

A few other climate facts to ponder:

-Global CO2 is increasing and continues to increase (see top panel in figure above).

– Globally, 12 of the 13 warmest years on record have occurred since 1995.

-Intensity of hurricanes and cyclones is increasing (Webster et al., 2005).  While Fox and Friends were happily using the Blizzard of 2011 to debunk climate change; did they notice the most powerful cyclone on record was slamming into Australia?

-Frequency and severity of droughts is increasing worldwide (Burke and Brown, 2006).

-Glaciers are disappearing.  If you want to go to Glacier National Park and actually see a glacier, you need to hurry.   In 1850 there were 150 glaciers in the park.  Today there are 25 and they will likely be gone in 10 years.


Winter Trade Show Report

Disclaimer: The information and images below should not be construed as any sort of recommendation, remedy or advice. Just some cool and/or weird stuff I saw at a green industry trade show. Plus this blog needs more photos.

Was at the Mid-Atlantic Nursery Trade Show (MANTS… and yes, there is a Pennsylvania version…PANTS) in Baltimore a couple of weeks ago.  It’s a wonderful opportunity to visit with past students (now gainfully employed – yay!).  I also get to personally thank the nurseries and other businesses that generously support our Horticulture Department and Garden.  I’m more "herbaceous" so I tend to get more (professionally…and emotionally) out of the floriculture summer trade show and conference in Columbus, Ohio (OFA)  If you dig hot new tropicals, annuals, and perennials – it’s THE place to be.  MANTS tends to be more landscapy/woody.  There are umpteen wholesaler booths filled with dormant, ball & burlapped trees and containerized shrubs. There are WAY too many Bradford pears still out there (see Bert’s post below).  Honestly. 

Foot traffic was good (10,000 + registrants) for the 300 exhibitors: wholesale nurseries, garden center suppliers, liner and plug growers, landscape and nursery equipment manufacturers.  Also, all of the allied businesses you might not think of – inventory software, nursery insurance companies, universities and colleges, grower organizations, tag and pot manufacturers, etc.,  always a fascinating vertical and horizontal cross section of this business of growing and selling plants.

On with the show…

Propagation nurseries make the world go ’round.
This IS the proverbial candy shop for greenhouse and nursery growers.  Each flat holds 36, 78, or 105 little plants.  Two flats…would fit in my tote bag. Heh.

Succulents continue to be hot. Here’s Kalanchoe thyrsifolia ‘Fantastic’.
Fantastically awesome.

Even better…check out the pot made from (very) compressed rice hulls. Nice color, pretty shape, biodegradable. You’ll probably see more of these in the near future.

Display promoting the book "Creating a Deer and Rabbit-Proof Garden".  Artificial flowers – that may be the ticket…no, wait, it’s an artificial deer, too.

WANT. My 1972 John Deere 750 is on its last legs/tires. Plus this one would fit down our blueberry rows, AND it has a cup holder.  The brochure is now pinned above my desk.

Great name for a nursery:

that’s Holly, Woods, and Vines if you can’t read it.

Also the home of…

Faux moss-covered faux rocks. Intriguing.

Finally, there’s always a peek at trends in pots (pottery pots), garden art (tasteful or not) and other items coming soon to your local independent garden center…

Lots of antique and rustic looks out there, also galvanized is big.
I loved the fishy pots. Alas, one can only look, and then place an order. Minimum quantity – one pallet. Maybe if we all went in together…

Snow falling on cedars…not always a good thing

Seattle had its first snowfall last week – a mere 3-6″ – and the city shut down.  (Yes, those of you in the snowier parts of the midwest and east can laugh…but we’ve got hills.  That’s the main problem.)  It was unusally cold, so the snow that fell was the light, fluffy kind that I remember from our Buffalo years.

Every year someone writes to ask whether they should remove the snow from their trees and shrubs.  Here’s what I suggest:

1)  If it’s very cold and the snow is dry and light, I advise leaving the snow on.  It serves to insulate tissues from freeze damage.

2)  If the snow is wet and heavy (i.e. temperatures are not that cold), you should remove as much as possible.  The insulation isn’t necessary, and the weight load can permanently damage trees and shrubs.

This damage can’t be easily repaired; the only alternatives are to cut bent trunks and branches out entirely (no stub cuts!), or to tie them up.  Not being into plant bondage, I generally cut bent branches away.

The Glories of The Winter Greenhouse

I’m a Southerner. With a capital “S”.  Which is why I am Suffering, with another capital “S”. Here in the Blue Ridge mountains of western Virginia, we have officially surpassed Anchorage and Denver in total snowfall for the season. Today’s batch adds up to 24″ on the ground at our farm.

Blueberries in the snow. If one more person says “Probably good for all the insect problems,” I’m going to get violent.

The chickens are not happy. They’ve been cooped up (ha! I didn’t really mean to do that!) for 10 days straight. I myself suffer from cabin fever, limp hair, seasonal depression, and a persistent cough.

Hell no, we won’t go!

What keeps me from going totally nuts? Only the best $12,000 ever spent – no,no, not granite counter tops…it’s our very own greenhouse. This modest 24′ x 48′ polycarbonate sheet hoop house may not resemble a Victorian conservatory (you can get one of those beauties here), but it works like a champ.  Yes, we have greenhouses on campus for research and teaching, but that’s work; and pet plants are frowned upon.

Nothing beats your own private winter hideaway. My plant-diva-friend Elissa uses her crowded greenhouse for not only her immense plant collection, but also a festive (if cramped) happy hour.

As sleet pelts the roof, I’m surrounded by green: tropical plants dug up from the garden before frost and those “pets in pots” accumulated from hither and yon.  The humidity is wonderful – I can hear my skin go “aaahhhh” after a couple of hours.

Herd o’ Agaves and succulents. They’re perfectly happy with the cool temperatures – several are blooming.

I’ve dreamed of one for years; then finally took the jump 16 months ago. Again, it’s nothing a homeowner’s association would ever approve of; just a commercial-grade, heavy duty, Quonset-type production house. Stylistic concerns were sacrificed for square footage. The most common complaint from home greenhouse owners is “I wish I had built a bigger one.”

The other concern is heating costs. It has a propane heater, and propane’s not cheap, nor environmentally friendly. But we run it pretty darn cold – around 48 F night temperatures, which certainly helps. Are the tropicals thrilled? Not really, but they’re alive and hanging in there (however, the begonias are really grumpy right now).

Some PVC pipe + overhead misting + heating mat = broccoli spinach, and basil seedlings, happily germinating at a 75 F soil temperature, despite an air temperature below 50 F. Basil?! Yes, I realize I’m totally jumping the gun timing-wise here, made worse by the fact that I teach both greenhouse management and ornamental plant production (do as I say, not as I do!).

Yep, more fun than you can shake a shovel at!
I’ll take your questions, comments, and snowballs now…