A Challenge

As I was looking over the label on a bag of fertilizer this morning I was reminded of the time, a few years ago, when a friend of mine and I went to a local K-mart and decided to see what the people in the gardening section knew.  We started small—we went over to a bag of fertilizer and my friend asked what the three numbers on the bag meant.  Now, as most gardeners know, those numbers indicate the amount of nitrogen, phosphorus and potassium in the fertilizer.  Unfortunately the guy we asked told us that those numbers were actually a computer code…We never did find out exactly what this computer code was for.  I have no idea why the guy couldn’t just say “I don’t know”.  We had intended to ask more questions, but both of us were too stupefied to continue.

So I have a challenge for all of you this weekend—I’m curious to see who takes it up—go to a box store, or a garden center—your choice—and ask them what the three numbers on the bag of fertilizer are for.  You can list responses in the comments section below—or feel free to e-mail me directly at gillm003@umn.edu if the answers are too embarrassing!

They said to write about it, so I will…

Please tell me – am I crazy?  Or just not the gardening trend-setter that I should be?  Should I be spending $10 on this? Check out this excerpt from Garden Cuttings Newsletter, with the note “Please feel free to use this information in your stories and columns”:

“Instead of sending dried leaves and other yard waste to the landfill, compost it! DeComp-9 Organic Compost Booster speeds up the composting process with patented microorganisms that quickly break down leaves, grass clippings and other yard waste. When added to compost, the microorganisms in all-natural DeComp-9 will grow on organic material, feed on decaying and dead plant matter and convert this waste to nutrient-rich compost that helps build stronger and healthier plants. Just mix DeComp-9 with water according to the product label and apply on compost piles. Each 20-gram package of DeComp-9 makes 10 gallons of solution – enough to treat 27 cubic feet of compost material. DeComp-9 is available for about $10.”


High-end WOW (Why oh why)

A few weeks ago I was lucky enough to speak to the Portland Garden Club and see some absolutely gorgeous private gardens.  But alas…even in the midst of such botanical riches I still managed to find something to make me shudder.

Now I have nothing against garden remodels – or boxwood hedges (though I generally find them unimaginative).  But here’s a good example of shrub salvaging gone horribly wrong:

Deadwood boxwood

And again

It will take a long time for these boxwoods to fill in.  If you’re going to spend the kind of money that’s going into this remodel, why get chintzy with the hedge plants?

Maybe green spray paint is in order?

Be a Part of History!

Here at the Garden Professors we pride ourselves on being on the cutting edge of technology.  In fact, we’re so tech savvy we didn’t even whine when FaceBook foisted a new homepage format on us for no apparent reason.  So it’s only fitting that we offer you, Mr. and Ms. Garden Professor Blog reader, an opportunity to participate in the first ever landscape horticulture research project designed by social media.


Here’s the deal.  My current research project on water and nutrient management of trees in container production has left us with over 100 ‘Bloodgood’ London planetrees in 25 gallon containers.  What I need from you are ideas for a study plan on what to do with the trees next.


Of course, as with any major research project, the first step in the rigorous scientific process is to come up with catchy acronym for the study.  I propose “the SOcial MEdia DEsigneD TRansplant ExpErimental Study” or SOME-DED-TREES for short.  Needless to say, I am willing to consider alternatives.  In any event, we have a unique opportunity to investigate post-transplanting growth, development and physiology of landscape trees.


So here’s what we have: Approximately one hundred,  2” caliper trees, grown in containers in a standard mix of 80% pine bark and 20% peat moss.  Trees have been grown for two years in essentially standard nursery culture – daily irrigation and 60 grams of Nitrogen per container.  The subject of the original study was fertilizer source; half the trees were fertilized with Osmocote and half received the same amount of nutrients from organic fertilizers. After two years we have not seen any difference in growth or foliar nutrients between the treatments. Nevertheless, I will need to include the prior treatment as a blocking variable to eliminate any potential confounding effects.  Beyond that it’s wide open.  We could have 6 treatments x 2 blocks x 8 trees = 96 trees.  I strongly suspect in the final analysis the block effect will be non-significant and we can consider there to be 16 replicates, but life is full of surprises.


So, what tree establishment or tree care question is burning a hole in your brain?  “Shaving” or “butterflying” container rootballs?  Fertilizing at time of transplant?  The latest biostimulant?  Crown thinning at time of transplant?  Frequency of post-planting irrigation?  Width of the planting hole – how wide is wide enough?  Send me your suggestions and we will set up a poll to vote for the top choices.

Beer and 1984

1984.  That’s the year that the last professor here at the University of Minnesota published a paper about peanuts.  He had tested a number of different varieties, some of which we’re testing now, and found that they do quite well in Minnesota.  Then for the next 26 years there was a lull.  And now?  We have peanuts!  Boiled peanuts and man are they good.  But…will we end up in 1984 again?  How do we make sure that our peanuts don’t disappear into academic oblivion?  We’ve got to find a restaurant, a bar, a gas station, something, who wants to try something new – we need demand.  Maybe the state fair?  We’ll see.

I give a lot of talks throughout the US.  It’s something that I enjoy, but, honestly, a year or two after I give a talk in a location I usually forget many of the specifics – they bleed together.  Sure, I remember that I gave a talk in Green Bay (for example) – and I remember the people and the botanical garden (both of which were great) – but I don’t really remember the talk itself.  Well, this past Tuesday night I gave a talk that I’ll remember forever.  There’s a bar in Minneapolis called Bryant Lake Bowl which is connected to a bowling alley and a theatre.  Our University Museum, called the Bell Museum, hosts a monthly scientific talk there called Café Scientifique.  The audience, about 90, is waited on by the bar staff during the talk and so everyone is quite comfortable.  The speaker may also partake if he or she so desires (how could I resist – after all, it was the only compensation I received).  So I had a pint of Surly – on an empty stomach – during the talk!  I’m a lightweight, so let’s just say I was relaxed.  It was about an hour presentation followed by almost an hour of questions.  I don’t think it was my best talk ever, but I don’t know that I’ve ever had a better time giving a talk (The title, by the way, was The Truth About Organics).  It was an audience largely composed of a demographic I rarely get to talk to out side of my classes – young (20-30 yr old) people who were very curious about where food comes from and who really hadn’t spent much time thinking about it before.


An unusual company

This week I’m in Charlotte, NC as a guest of Bartlett Tree Experts.  In addition to providing tree services, this company also maintains the Bartlett Tree Research Laboratories and Arboretum. The latter includes over 300 acres of tree collections and ongoing research trials.  Here’s a sampling of the tree research we had a chance to observe:

Demonstration espalier pruning…

…and pleaching

Comparison of root barrier materials.  This area was covered with a sidewalk for a number of years and then exposed to observe tree rooting patterns.  The purpose of the research was to find which barriers were most likely to prevent sidewalk lifting and cracking.

A control – no barrier, lots of roots!

Black plastic – lack of rigidity allows roots to grow over (and through) the plastic, then under the sidewalk.

18″ rigid root barrier.  One of the more effective means of keeping roots out.

Removing circling roots before planting

A tree whose roots had been corrected before planting.  I think this had been planted in 2007, then lifted a few weeks ago.

A tree without root correction.  It didn’t grow any better than the corrected tree, and those circling roots are well on their way to becoming girdling roots.

This company employs a number of PhDs whose research is routinely published in arboricultural and horticultural journals.  It was fun to finally meet these researchers whose work I’ve been following for years.

Wouldn’t it be great if more companies put this much effort towards research?

Fall color time…

Did you ever know one of those annoying people who always talks about how great everything is back wherever they were from; the kind of folks that make you want to say, “If things were so much better there, why are you here?”  I have to confess I’m one of those people.  No one’s ever actually given me the “If things were so much better there” line, but I’m sure my Michigan friends have been tempted.  I’m warming to things Michigan but I suspect in my heart of hearts I’ll always consider myself a Washingtonian.


That said, there are some ways that Michigan has Washington beat.  We have long, lovely sandy beaches where the water gets warm enough to swim in; which for me means at least 75 deg. F.  Washington has great beaches, of course, but you’ll never see anyone over the age of 12 in the water without a wetsuit – even in August.  We have real thunderstorms spring, summer, fall and occasionally even thundersnow in the winter!  Western Washington is lucky to have two or three bouts of muffled thunder each year.  And we have real fall color thanks to red maples, sugar maples, oaks, sassafras, tulip poplars and others.  Conifers dominate the Northwest and what few large hardwoods there are (big leaf maple, red alder, black cottonwood) drop their leaves inconspicuously without much fanfare.  Vine maples try to make up the difference but usually just add a splash of color here and there.


As with many states with rich fall color, “leaf peeping” or “leaf looking” is a popular fall pastime and many people plan fall getaways to northern Michigan to enjoy the color show.  For someone in a position like mine, that means calls from media, AAA, and others asking for predictions on whether we’ll have good fall color.  Of course it’s difficult to predict since conditions during fall itself (i.e., sunny days and cool nights) are among the biggest determinants.  We do know that drought conditions late in the summer can result in early leaf drop or limit production of some secondary pigments, resulting in a shorter and more muted display.  For us in Michigan that suggests a below average fall color show up North since many counties have received 50% or less of their normal rainfall since July.


For those interested in learning more about fall color, I high recommend ‘The Fall Color Guy’ website http://biology.appstate.edu/fall-colors The site is maintained by Dr. Howie Neufeld, Professor of Plant Physiology at Appalachian State University.  Howie and I crossed paths at the University of Georgia when he was a visiting scientist and I was a Ph.D. student.  He provides some of the best information I’ve seen on the science of leaf color and his essays on the website are good reads.

My Thoughts on 2,4 D


My sister, who lives in the Pittsburgh area, just gave me a call.  She and her husband have two kids and a lawn and she wanted to know my feelings about using herbicides to keep the grass free of weeds.  When we were growing up our parents had a large lawn (and lots of fruit trees) and it took two of us two hours to mow the whole thing.  It kind of turned her off to grass.  The truth of the matter is that she doesn’t even want the lawn she currently has, but her husband wants it – and he wants it weed free.  So she called me giving me the “you’re supposed to know about this stuff” line and asked me what she should do.  My response was that the herbicide her husband would be applying (trimec) wasn’t on my list of super bad things to apply, but that, in my opinion too many people want their lawn too free of weeds.   I don’t see anything wrong with applying an herbicide once a year – it won’t keep a lawn pristine, but it will knock out most of what most people want knocked out.  Why do people insist on having spotless yards – applying herbicides from three to six times per lawn per year?  It’s insane.  Not so much for the safety of humans, but for the good of the lawn ecosystem.  It’s good to have a mix of different plants – it’s healthy.  Using an herbicide really cuts down on you biodiversity, and can affect the safety of dogs too.  You see, 2,4 D, probably the most used pesticide on lawns in the US (and a component of trimec), isn’t rapidly excreted by dogs.  If we are exposed to 2,4 D we just pee it out – our kidneys process it rapidly and out it goes.  In a dog’s system this chemical sits and sits.  It is for this reason that 2,4 D is considered particularly bad for dogs and is suspected of potentially causing cancer.

One more note about dogs.  The reason that lawns get dog spots is because of the amount of nitrogen in the dogs urine – it kills plants – it IS NOT because of the pH of the urine.

Weird and Wonderful Plant Wednesday: Threefer!


This is a tale of three plants in my garden that would make the cruelest of multiple choice answers. Heh. Hence the inclusion of all three in this post:

a. Manihot esculenta

b. Abelmoschus manihot


c. Abelmoschus esculentus

d. All of the above

e. Aaaargh.

Manihot esculenta is Cassava or Tapioca; worthy of an entire post on its own. But the choice ornamental version is M. esculenta ‘Variegata’ or variegated tapioca.  I first saw it (gawked and squealed, actually) at Allan Armitage’s fab trial garden at the University of Georgia. Full sun, hot as blue blazes – not the usual environment variegated plants thrive in.  But this South American native loves it. It’s worked its way north in the trade; now nearly every plant nerd garden has it.  Perfect in beds or containers, it makes a lovely, well-behaved clump in temperate zones – a big shrub in warmer areas.  Interestingly, Manihot is in the Euphorbiaceae family; the other two are Malvaceae (hibiscus family).  Hardy only to Zone 9, unfortunately.

Manihot at the UGA garden in 2004. Love those red stems!

In our home garden. A bit of a shady spot, hence the less-vivid coloration.


Abelmoschus manihot is variously known as sweet hibiscus, sunset hibiscus, etc. and remains rather obscure. It’s easy to grow from seed, plus reseeds gently where happy (like the gravel paths in our kitchen garden).  Not much to look at until late summer, then the big lemon-yellow flowers unfurl – usually one or two at a time on each plant. The seed pods march up the stem, resembling a smaller version of okra.  Gets tall – up to 6’ or so – but the sturdy stems don’t need staking. Collect seeds from the dried pods to start next year.

The foliage is edible – I’ve gnawed a leaf or two but was underwhelmed. Maybe in soup.


The flower of Abelmoschus manihot is very similar to but a bit larger than those of okra…

Marvelous pods in the fall at Chanticleer.


Finally, the most common –  Abelmoschus esculentus – Okra.  Hitting its stride right now in the home garden.  Extremely ornamental, especially the red-stemmed varieties.

Okra ‘Hill Country Red’ at the Atlanta Botanical Garden this summer. Gorgeous!

The important bits.

Okra is a very unique veg.  You may be cringing from some past okra mishap, but I urge you to try it 1) fresh and  2) prepared correctly. Yes, it’s a bit mucilaginous, but what makes it gooey also serves a wonderful thickener for gumbo, stews, and the like. Pickled okra makes an exceptional cocktail garnish for vodka martinis (add a splash of hot sauce for a  Cajuntini).  I love okra dearly but never buy it in the store – as it sits around, the pods become woody and tough.  Try it fresh from the farmer’s market or even better, the back yard.  Not trying add to the food-blog-saturation point, but please allow me to wander off-topic and share my favorite fried okra recipe. The deep-fried, breading-buried stuff normally sold as
fried okra is far, far inferior.

Holly’s Fried Okra
(Materials and Methods)


Pick a mess* of okra. Slice up your pods (no more than ¼” to 1/3″ sections.  If it’s difficult to slice, discard that pod – too old/tough) and toss into a bowl with a sploosh of buttermilk, just enough to moisten it. Add salt, pepper, and a dash of cayenne. Stir gently.  Get a big fry pan or wok (okra needs its space) and heat some veg or olive oil. Not a lot, just a few tablespoons. Don’t let oil get smokin’ hot, don’t want to burn it. Now throw a big handful of cornmeal into the bowl with the okra and stir gently again. Some will stick, some won’t. You should be able to see the okra, not just blobs of coating. Move okra to hot pan with a slotted spoon, giving it a shake over the bowl so you don’t get a lot of extra cornmeal in the pan. Just enough for one layer – don’t crowd the pan or it will be soggy. Toss gently over medium heat for about 5 to 8 minutes until some corners are very dark brown and crispy and everything else is either green or golden.  Remove to paper towel-covered plate; add a dusting of kosher salt, then start the next batch (replication).  Eat the first batch while standing there making the second batch. Helpers will magically appear. The first batch NEVER makes it to the table in our house.

Crispy, non-greasy, okra goodness!

*mess = “as much as you need for your meal”, be it for two or ten. This recipe uses about three cups of slices – though can’t say I’ve ever measured. Enough to feed two or three (two if they really like it). Adjust other ingredients accordingly.


Pop quiz answer

Today’s post is a follow-up to yesterday’s quiz on foliar fertilization.  I asked our blog readers to match the needle nitrogen content of Nordmann fir trees with the fertilizer treatments they had received.

Nutrient deficient Nordmann fir

The correct order is:

1)      control: no fertilizer 0.98%
2)      soil applied controlled release fertilizer 1.70%
3)      foliar nitrogen fertilizer 1.14%
4)      soil applied fertilizer + foliar feed 1.91%

While the foliar fert had a small effect, it’s important to note that, from a statistical standpoint, foliar fertilization did not significantly increase needle nitrogen concentration.  Moreover, foliar feeding alone was not sufficient to overcome the nitrogen deficiency of the control trees.  The main effect was from fertilizing the soil (actually container substrate is this case).

The take home message is that plants have evolved (or God designed them, if you prefer) to take up nutrients from the soil through their ROOTS.  They’ve been doing it for millions years and have been getting along quite nicely, thank you.  No matter how slick and clever the marketing, attempts to ‘short-circuit’ the process such as foliar feeding or trunk injection are short-term solutions at best or, as in this case, almost totally ineffective.  Foliar feeding and trunk injection treat symptoms, not causes.  Plant nutrient deficiencies occur because: 1) an element is lacking in the soil or 2) because the plant can’t absorb enough of the element (e.g., iron chlorosis).  Effectively dealing with a plant nutrient problem requires understanding which of those two situations is occurring and why.