September 2012 – The Garden Professors™

Fall for Ornamental Grasses

I’ve written about ornamental grasses previously – they really are one of the toughest, most useful yet under-appreciated groups of garden plants. Most provide at least three seasons of interest, but fall is when they really shake their pom-poms.

On a recent conference trip to western Michigan with pal and plantsman Paul Westervelt, we stopped by the trials at Walter’s Gardens of Zeeland – one of the largest perennial propagators (wholesale) in the country.

It was a beautiful, breezy day in their extensive gardens, and the grasses were positively alive with light and motion (and kittens – seven or eight, I think). What a fantastic afternoon.

Here are a few recent introductions that knocked our socks off. All are hardy to at least USDA Zone 5, heat tolerant to Zone 8 or 9, and the non-natives have been screened for any invasive tendencies. All are patented.

Panicum virgatum ‘Dust Devil’

There are many great cultivars of our native switchgrass out there; but few come in under 6’ or 7’ – problematic for the small garden. Dust Devil is comparatively petite – 3 to 4 feet tall, blue-green foliage, and resists the rain beat-down that often happens to the rangy cultivars. Selected by Michigander Gary Trucks.

Pennisetum alopecuroides ‘Burgundy Bunny’

Paul and I were especially impressed by this sport of ‘Little Bunny’. I’ve grown tons of ‘Little Bunny’ which is eminently useful for a pouf of “grassiness” at the front of the border. ‘Burgundy Bunny’ brings terrific color that only gets better in the fall, in the same small package. From Walla Walla Nursery and introduced by Plant Haven.

Paul models Pennisetum alopecuroides ‘Red Head’

Nothing petite about this monster Fountain Grass. Wow. 5’ tall and as wide, with gigantic foxtail plumes. As with most Pennisetum species, the show starts mid-summer and continues through fall. Selected by the perennially prolific Brent Horvath of Intrinsic Perennials.

Schizycharium scoparium Blue Heaven™ (‘MinnBlueA’)

Selected by grass maven Dr. Mary Meyer from her trials at the University of Minnesota. Mary has found a nice Little Bluestem that has outstanding foliage color (gets even better as the season progresses) and a very upright habit that fights the flop. Native across much of North America and perfect for awful sites, Little Bluestem laughs at clay, heat, and drought, once established.

Andropogon gerardii ‘Indian Warrior’

Little Bluestem’s big brother of the tall grass prairie. Another upright flop-fighter, this Big Bluestem is from Brent Horvath/Intrinsic. I’ve enjoyed Andropogon in my garden (got it from Paul) – the colors are amazing- but by summer’s end, they’ve flopped all over their neighbors. Can’t wait to give ‘Indian Warrior’ a try.

Lots more info on these and other grasses and perennials at Walters Gardens’ consumer portal www.perennialresource.com

Kittens in the grasses. Ahn.

Finally: when in Grand Rapids, stop by HopCat for a tremendous selection of Michigan craft beers and hard ciders and the suitably-name Crack Fries (yes!!!).

Point of view: tree fouls out

A few weeks ago the Seattle Times ran a story about a tree whose existence is straining a long-term neighborly relationship. The feud’s between former Mariners first baseman John Olerud and his neighbor Bruce Baker, both of whom live in the Clyde Hill area (a bit north of Bill Gates’ place in Medina). Baker owns a Chinese pine (red or white, I’m not sure, but I’m guessing red based on the photos) which interferes with Olerud’s view of Lake Washington and the Seattle skyline.

You can read the entire story on the link above, but I’m particularly interested in the following points from the article:

"The tree, with a 2-foot-thick trunk, was there long before the Oleruds built their home."
Baker "wasn’t willing to cut down a tree that his arborist called very rare and valued at $18,000."
Clyde Hill is "one of the first in the nation to adopt a process for condemning trees that block too much of neighbors’ sunlight or scenic views."
"You guys saw the trees," Olerud said at the board hearing. "They’re not attractive trees. I would say they’re the kind of tree that only an arborist would love."

So…what would YOU do if you were on the board making this decision? (Be sure to do your homework and read the entire article before weighing in.)

The wackiness continues

It seems like every year we end up talking about ‘weird’ weather; either it’s extreme heat, extreme cold, too much rain, not enough rain, and on and on. Here in the upper Midwest and other parts of the central US, however, 2012 is clearly a year to remember. Our winter was fairly unremarkable until we hit 8 days over 75 deg. in mid-March. This pushed our growing degree days up at least 3 weeks and set the stage for widespread late-freeze damage in April, wiping out the state’s cherry, peach, and plum crops. Summer turned out warm and dry, highlighted by record-setting heat in July.

Weekly average high temperatures from MSU Hort Farm weather station: 2012 versus average of 15 previous years.

Now that we’ve seen some relief from summer’s drought and heat, we’re experiencing one more weather-related phenomenon: stress flowering. At my place I had lilacs and azaleas start to flower in August. We have also had reports of crabapples flowering in the eastern part of the state. Trolling around the web, I ran across a photo of magnolias blooming this month in Kansas City.

Magnolia flowering in mid-September. Source: Kansas City Star

So, what’s going on? Severe heat and drought can cause plants to go into a state of eco-dormancy. Typically we define “true” dormancy as a state where plants won’t grow, even when environmental conditions are favorable. Eco-dormancy represent the flip-side; plants should be growing but can’t due to severe environmental stress. In some cases the stress can induce flowering, such as we’ve seen this year. We have also seen examples of trees that have re-flushed, sending our new leaves after shedding leaves during the peak of the drought.

Will any of this cause long-term problems for trees and shrubs? Probably not. Stress flowing tends to be sporadic so most flower buds on a tree or shrub are likely to be unaffected. Shoots that re-flush late in the summer may or may not be able to harden off before winter. If not, they will be subject to freeze injury just like shoots that flushed earlier the spring. The main concern for 2012 is the cumulative toll of our environmental extremes.

Clever Things I Saw This Summer, Part 1

I’ve been wanting to share a few silly things with you from my travels and travails this summer. But I’ve been a bit hesitant, due to the gravity of recent posts, comments, and related hoo-ha (I was completely unaware there was a cornmeal controversy).

I sure appreciate and admire the guts and grace with which my GP colleagues present their cases and engage our readers. Important topics, all.

Which makes this segue even more awkward…Look! A jellyfish made from succulents!!!

Start with a fabulous assortment of Kalanchoe, Echeveria, Sedum, Aeonium, etc.

Turn wire hanging basket upside-down. Stuff with sphagnum moss. Cut a circle of mesh and wire across the bottom (was the top).

Plant with little succulents (I’m sure that’s how they started out). I think the tentacles are Crassula species. Hap, our man from Cactus Jungle, would know the species (segmented one might be C. muscosa, but the curved one really made them look tentacle-y).

Add a hook and chain. Slap on a $200 price tag (yow!).
Voila! A jellyfish.

If ever near Alexandria, Ohio (just east of Columbus) stop in to visit Chris Baker and the gang at Baker’s Acres. Greenhouses are chock-full of amazing plants and ideas such as this one, plus the restroom decor is worth the trip.

Why I Don’t Worry Too Much About Organic Fruits and Veggies

Let me tell you something you already know. If you grow something in your own garden you’ll know exactly what poisons were or weren’t put on it, how much fertilizer was used, and furthermore it will taste better.

If you buy your apples from the guy down the street who you’ve known for 20 years you’ll be able to ask him what he used to grow the crop, why he used it, and you’ll have the satisfaction of supporting a local industry. And yes, those apples will taste better than grocery store apples.

If you go to a farmers market you’ll be able to ask the people there exactly what they did to their crops, and why they did what they did. And you’ll feel good about supporting the local economy. And yes, the food will taste better than anything from the grocery store.

If you walk into a grocery store or Target, or Kmart or whatever and pull a fruit or vegetable off the shelf which has the USDA Organic Label on it and say to yourself “Hey, I’m doing something good for my family and the environment” then, in my opinion, you’re fooling yourself.

There, I said it. I believe that, AS USDA ORGANIC CERTIFICATION NOW EXISTS, the USDA Certified Organic label does not provide a significant indicator that the fruit or veggies you’re buying provide a significant benefit in terms of human or environmental health. Please note that I’m not saying anything different than our government does – what they say is: “Organic is a labeling term that indicates that the food or other agricultural product has been produced through approved methods that integrate cultural, biological, and mechanical practices that foster cycling of resources, promote ecological balance, and conserve biodiversity.”

Notice that they never say that organic is superior to conventional production, simply that organic uses practices that “foster cycling of resources, promote ecological balance, and conserve biodiversity”. Though many of you may not believe it, conventional growing uses many of these practices too – producers know that if they don’t pay at least some attention to sustainability then they will lose money over time.

So why am I talking about this today? Well, I’ve had a few requests to discuss that new meta-study that came out a few weeks ago which showed that organic food has the same nutritional value as food produced conventionally. Big deal. Plenty of other meta studies have shown essentially the same thing –the quality of organic is LARGELY the same as conventional with a few nutrients (often vitamin C) a little higher in organic and a few (often protein levels) being higher in conventional. Anyway, to make a long story short, I don’t know why this study got more press – maybe they have better PR people at Stanford where the study was put together.

Look, the reason that one food has more nutrients than another has much more to do with the food itself than whether the food was grown organically or conventionally. No matter how you treat a McIntosh apple, it will never have as much vitamin C as a Granny Smith apple. Period. Folic acid will always be greater in bananas than grapes. Period. If you’re worried about getting enough of a particular nutrient then eat foods high in that nutrient. If you’re worried about a lot of nutrients then eat a varied diet.

Of course the study also says that synthetic pesticides are more likely to be on conventionally produced foods than organically produced foods. OK, I’ll buy that. Makes perfect sense….but tell me, how much organic pesticide is on organically produced foods? And how does it affect you? If a farmer uses spinosad, an insecticide used by organic growers, it can be present at low levels in food, as can other organic pesticides such as pyrethrum. But since residues of these organic pesticides are rarely tested you have no idea how much is in there.

Look, if you want to avoid pesticides on your fruits and veggies altogether and can’t grow a garden or go to a farmer’s market, then you should avoid foods where pesticides need to be used. These are the only foods where you can count on growers, organic or conventional, avoiding pesticides (No farmer WANTS to use pesticides – they’re expensive!). To find foods where pesticides are less likely to be used just go to that crazy dirty dozen list which the Environmental Working Group puts out (which I think is a bit ridiculous – but I’ll leave that alone for now since this post is getting long) and select fruits and veggies from the clean 15.

In terms of organic production being better for the environment, as long as organic growers can use copper to control diseases, I’m concerned about how long term applications of this copper will affect
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soils on land devoted to organic production over the long term. I’m also concerned about fertilizer runoff and leaching in organic production – same as in conventional production. Nitrogen and phosphorus from manure can and do run off just the same as nitrogen and phosphorus from synthetic fertilizer.

In both conventional and organic systems, the impact that production has on the environment comes down to the responsibility that a given producer takes for doing the right thing and protecting the environment. To say otherwise is just silly. There is so much leeway in the USDA organic system that there is plenty of opportunity for a USDA organic producer to do things that will make their operation significantly worse for the environment than a conventional producer of the same crops.

Deconstructing the cornmeal myth

Back in June of 2010, I wrote about an online column that recommended applying cornmeal as an antifungal soil amendment. (Important note: we are not talking about corn gluten meal. Just cornmeal.) The upshot of the post was while some gardening personalities extol the use of cornmeal to kill soil pathogens like Rhizoctonia and Sclerotinia, no published science supports the practice. The post was effective in encouraging the author of the referenced online column to update her information, but the controversy didn’t die. In fact, new comments have been added to the original post on a fairly consistent basis, mostly in the form of personal anecdotes or angry rebuttals. Some commenters, however, have tried to carry on rational discussions, so today we’re going to look at cornmeal from a slightly different angle: what effect does it have on microbes in general?

To start, let’s look at the Stephensville, Texas research that’s most often highlighted by cornmeal proponents. There’s no peer-reviewed work published on this specific research, but in an online copy of the Texas Peanut Production Guide I found a paragraph referring to “Biological Control of Soil-Borne Fungi.” Here it is in its entirety:

“Certain fungal species in the genus Trichoderma feed on mycelium and sclerotia of Sclerotinia minor, Sclerotium rolfsii and Rhizoctonia spp. All peanut fields in Texas tested to date have natural populations of Trichoderma. For several years, tests have been conducted in Texas using corn meal to stimulate Trichoderma development as a way to control the major soil-borne disease fungi. When yellow corn meal is applied to fields in the presence of moist surface soil, Trichoderma builds up very rapidly over 5 to 10 days. The resulting high Trichoderma population can destroy vast amounts of Sclerotinia, Sclerotium and Rhizoctonia. This enhanced, natural biological control process is almost identical to the processes that occur when crop rotation is practiced. The level of control with corn meal is influenced by organic matter source, soil moisture, temperature and pesticides used. Seasonal applications of certain fungicides may inhibit Trichoderma. Testing will continue to determine the rates and application methods that will give consistent, economical control.”

And that’s all there is on the topic. Most scientists would conclude that further testing was inconsistent and the researchers abandoned their efforts without publishing anything further. But this summary is at least a starting point, though it contains no data, references, or even authors.

First, there’s no argument that Trichoderma is a powerful antagonist of some nasty pathogenic fungi. Likewise, cornmeal most certainly can encourage the growth of Trichoderma, both in the lab and the field. But cornmeal also encourages the growth of many other fungi – in fact cornmeal agar is commonly used for culturing fungi in the lab. So what about those three pathogenic fungi mentioned in the Texas peanut guide? Do they like cornmeal?

Indeed they do! Published research (about 20 or so articles) shows that cornmeal (not cornmeal agar) has been used to enhance growth of Rhizoctonia fragariae, R. repens and R. solani, Sclerotinia sclerotiorum and S. homoeocarpa, and Sclerotium rolfsii. In some cases the pathogens became more virulent in the presence of cornmeal.

Cornmeal is nothing more than a carbohydrate-rich resource that can be used by many microbes. If you happen to have a lot of beneficial fungi in your soil, cornmeal will feed them. If you happen to have pathogenic species in your soil, cornmeal will feed them too. So it depends on what fungi are already living in your lawn, vegetable garden, or rose bed on whether cornmeal will help, or just make disease problems worse.

The best thing to do – as the paragraph from the peanut guide suggests – is to mix things up a little in your landscape. Use mixtures of lawn grasses rather than growing a monocultural turf. Rotate plant placement in your vegetable garden every year. Add a microbe-rich organic mulch to your rose beds. Natural methods will keep pathogens in check much more effectively than a hyped-up home remedy that’s anything but antifungal.

UPDATE: Since this is a myth that refuses to die, I’ve published a peer-reviewed fact sheet on the topic. Feel free to pass on to others.

The new hardiness map’s obsolete! The new hardiness map’s obsolete!

I posted back in January about my excitement about the update of the USDA Hardiness zone map. While I acknowledged some of the shortcomings of the new map, I was excited because it was a big improvement over the old map, both in terms of content (more recent temperature data included) and presentation (interactive search features, better graphics).

Dr. Nir Krakauer, assistant professor of civil engineering in The City College of New York’s Grove School of Engineering, was less impressed, however, and has essentially declared the new hardiness map dead on arrival. Dr. Krakauer conducted his own analysis of climatic data and determined that much of the country is already a half zone to one full zone warmer than the new USDA map. Why the difference? The USDA zone estimates were based on a simple average of annual minimum temperatures from the past thirty years. Dr. Krakuar’s applied a regression analysis to account for more recent warming. One of the key observations of the new analysis is that winter minimum temperatures are warming much faster than average temperatures, leading to the new hardiness zone projections.

So, what do we do with this information? All of the limitations that we associate with hardiness ratings still apply. Most landscapes experience micro-climates that may be slightly colder or warmer than the surrounding area. Plus, winter hardiness is just one piece of information in plant selection (we also need to also consider sun exposure, pest pressure, soil factors – drainage, soil pH, and so on). Most importantly, average temperatures don’t kill plants, extreme temperatures do. So whether we look at long-term averages or try to account for the most recent trends; the extreme 1 year in 5 or 1 year in 10 is what will cause issues. For example, if Krakuar’s projection is right and we’re a zone warmer on average, then the greater Lansing area is now zone 6b (0 to -5 deg. F). We’ve been colder than that in 2 out of the last 4 years.

The press release that accompanies Dr. Krakuar’s study starts with an attention-getting line: “Gardeners and landscapers may want to rethink their fall tree plantings.” But really things haven’t changed that much from the past. How homeowners and landscapers use zone information is still a matter of risk tolerance. If I chose a zone 5 plant and we’ve really warmed to zone 6, I’ve lost nothing. If I gamble and plant zone 6 plants and we drop back down to -10 or -15 deg. I may be looking for replacements. And, of course, there’s the tendency of many gardeners to ‘push their zone’, so we may have folks trying to grow zone 7 plants in Lansing. Which is fine – as long as people understand the risk. Actually I think a better approach to hardiness zones may be a probability rating: Are you willing to take a 1 in 10 chance your plant won’t make it? 1 in 4? 50-50? As new climate data are added to the model, garden centers could post and update the odds, sort of like the latest line at a sports book in Vegas. Those that want the ‘tried and true’ can stick with the old zone 5’s; those that want to live on the edge can pay their money and take their chances.

The good, the bad, and the ugly. A reply.

Ginny Stibolt of the Florida Native Plant Society recently posted Native Plant Issues: The good, the bad and the ugly, featuring me as the ugly. I posted a reply on her post, which I include here. To keep things in context, I encourage you to read her post first.

Enjoy your weekend!

Hi Ginny:

Some comments and a few points of clarification.

On the first item, as a Federal agency the USDA is bound by the Executive Order on Invasive Species which defines natives as species that occur in an ecosystem “other than as a result of an introduction”. I suspect they tried to simplify the language for the National Planting day release when they substituted ‘naturally occurring’.

On the Arbor Day Foundation, I am fairly certain they use contract nurseries in various locations for their tree sales. In any event, they have plenty of trained foresters on their staff that understand the importance of provenance and they would not send trees from northern seed sources to Florida or vice versa. But I certainly can’t fault the idea of supporting the Arbor Foundation, declining their trees, and buying trees from a local nursery.

On the Google + Hangout discussion no one was ‘booted off’. These were straight and simple technical issues. If people watch the Youtube video, the audio sounds like Neil Armstrong on the moon. This is a new technology for most of us and we are dealing with some growing pains. I would have much preferred even numbers on each side. Having an imbalanced debate can work against the majority, too. As Wilt Chamberlain famously observed, “Nobody roots for Goliath.” That said, we did have a lively and cordial debate and I hope people will bear with the grainy images and tinny audio and take a look.

Kentucky coffeetree

I haven’t watched the video but I don’t think I said there were no natives that could be used as street trees here in Michigan. If I did, I misspoke. That might be true for Linda in the Northwest – if you look at the native tree list for King county you’d be hard pressed to find anything that could be recommended in good conscience as a street tree. We have a few more options here in Michigan. If we were looking for a street tree for Lansing or Detroit the list could include hackberry, honeylocust, Kentucky coffeetree, tulip poplar, swamp white oak, and red maple. But even this list makes urban foresters cringe because they think red maples are already over-planted, tulip poplar is weak-wooded, and hackberry is difficult to transplant. With regards to Mary Wilson’s comments, there is a distinction between street trees and landscape trees. Landscape trees could be anywhere on a residential or commercial landscape where they could receive irrigation or other care so there is broader list, in contrast to street trees found on street sides in tree lawns or tree pits. Street trees are subject to the ‘worst of the worst’ in terms of environmental conditions; minimal rooting volume, compacted soils, road salt, and reflected heat load; but they provided the ‘biggest bang’ in ecosystem services, especially cooling buildings and sidewalks.

Swamp white oak

This has been an interesting discussion and clearly I have touched a nerve. I have to confess I have never been vilified so much in my life, which has been a little discomforting but also strangely flattering. When I met with Jeff and Linda earlier this week Jeff commented, “Wow, I’ve never been able to sit across the table from the devil incarnate before!” Fortunately, I work in academia where we spend most of our days telling one another how stupid the other is. People that seek to avoid criticism generally don’t do well in this line of work. Peer review forces us to critically examine our statements and sharpen our arguments. I was pleased and gratified to see some of the changes proposed for FNPS website and literature – why leave ‘low hanging fruit’ around for critics? While I didn’t appreciate some the comments made about me, if I’ve caused this group and others to strengthen their arguments and re-examine some of their assertions regarding natives, then the slings and arrows I’ve taken these past couple weeks haven’t been in vain.

Poisoned bird seed and trust

Over the years I’ve said some nice things about Scotts Miracle-gro products, such as one of their potting soils, and some not so nice things, such as with their Round-up resistant Kentucky bluegrass. I’ve never thought of them as a particularly good or particularly bad company, just a company trying to do the best it could while being reasonably honest about what it was doing (You could argue that they tried to pull something fancy with the Round-up resistant Kentucky bluegrass, but I’m going to give them the benefit of the doubt and say they were just exploiting an obvious governments loophole – not exactly good, but hey, it’s a dog eat dog world out there).

But then the news broke that they had applied insecticides illegally to their wild bird food products, falsified pesticide regulation documents, distributed pesticides with misleading and unapproved labels and distributed unregistered pesticides. If you haven’t seen the article yet you need to look here.

Damn.

Anyone who has read much of what I write knows that I try to tell the truth about products to the best of my ability, to do this I rely on a lot of different sources of information, including information provided by the company itself. I trust that, for the most part, companies try to do what they say they’re doing (or not doing) in terms of letting us know what’s in their products. At the least I assume that they follow the government’s rules and regulations.

This is a serious breach of my trust.

How am I supposed to deliver the facts about Scotts Miracle-Gro products when I can’t trust them to do what they say they’re doing?

I mean really? How can I talk about their products again? I have no idea what’s in there.

I’m trying to think of something pithy to say next – but I’ve got nothing. I’m deeply disturbed that this could happen, and, at least for the time being, I just can’t, in good conscience, trust this company or its products. Sure, the company is saying all the right things now, but that’s not enough.

Here’s a thought – maybe they could publicly state that they’re not going to release the Round-up resistant Kentucky bluegrass – you know – to prove that they really are serious about avoiding doing things that might disturb the environment. And then actually do it. Yes – that would be a good start.

A plant riddle for you

This week Jeff, Bert and I are brainstorming new and exciting ways that The Garden Professors can invade…I mean integrate into…the gardening world. (We’re channeling Holly, who had a conflict with another even this week.) We’ll leave discussion of the particulars for another day. But that’s my segue into my text-short but picture-perfect invasive plant story.

Earlier this spring I was in Palm Desert and spotted a large clumb of purple fountain grass (Pennisetum setaceum) in a landscape:

So here is the riddle: Why did the fountain grass cross the road?

To get to the other side.