Neon continued!

I’ll follow Bert’s highly informative, thought-inducing post with something not statistically significant. Hey, it’s summer.

My last post on ultra-bright “neon” plants had a comment from Sarah…

“I saw some iresine in a local garden center the other day, sun coming
through it at just the right angle, and the shade of blazing pink that
came through was basically every Barbie accessory I ever had. It just
seemed wrong somehow. Took a picture of it with my phone.” 

Aside from a hilarious (and insightful) comment, she included a URL to her photo.

It’s so good I had to post it. The pink plastic-y glow is amazing.

Fab photo by Commenter Sarah of Iresine herbstii – chicken gizzard plant

I had to greatly lower the resolution so that the system would let me post it. At full size and resolution, it almost hurts to look at it.

Incidentally, I’ve always thought “chicken gizzard plant” was a bit of a misnomer. I’ve seen really fresh chicken gizzards, and Barbie would NOT want accessories in that particular shade.


How to lie with statistics

I’m attending the American Society for Horticultural Science (ASHS) meeting this week in sunny (and hot) Palm Desert, CA.  Tomorrow I will be presenting some of the early results from the SOME-DED-TREES study.  For those that are new to the blog, SOME-DED-TREES is the acronym for the Social Media DesigneD TREe Establishment Study.  Last year, my students and I established a landscape tree study in which the treatments were suggested by Garden Professor’s blog readers.  Actually, we ended up installing two studies: one to look at fertilization at planting and one to look at impacts of mulching at planting.  The trees were ‘Bloodgood’ planetrees grown in 25 gallon containers.  In each study we divided the trees into three root treatments: We “shaved” the outer roots to eliminate circling roots; we “teased” apart the circling roots; or we just planted the trees as is (or “Pop and drop” to use Linda’s vernacular).

I reported some of the results of the mulch study here on the blog last fall and will include some of those data in my talk tomorrow.  I am also presenting some of the data from the fertilizer portion of the study.  One of the ways we assessed fertilizer response is by using a device known as a SPAD meter.

 SPAD meters have been around for a while and they are very useful.  The device measures light transmittance through a leaf, which is highly correlated with leaf chlorophyll content.  Chlorophyll content, in turn, is highly dependent on foliar nutrition so SPAD readings often provide a useful indicator of plant nutrient status. 

Here at the meeting I am using my laptop, which means I am without my usual statistical and graphing software.  So in order to plot some of the data for my talk I am relying on Excel.  This gets me to “How to lie with statistics.”  When I calculated the means for this June’s SPAD chlorophyll index values this is the chart I got.  Looks like a pretty impressive response to fertilizer, doesn’t it?

SPAD chlorophyll index of Planetrees fertilized at plant (Fert) and control trees (No).

The problem is the scale.  Note that by default, Excel truncated the scale on the y axis to values between 28 and 36.  This is a big no-no in scientific circles.  Graphs scales should include zero or show if break if there is some reason the range needs to be truncated.  The reason truncating the scale is a no-no, as shown here, is that it makes differences look proportionately larger than they really are.  Advertisers use this trick all the time.  Next time you see a bar chart in a sales brochure or magazine ad, look that the scale – bet it doesn’t go to zero. 

Let’s look at the chart after I re-scale it.  It still looks like there’s still something going on with fertilizer, but it doesn’t make you go, “Whoa!” like the first chart.

SPAD chlorophyll index of Planetrees fertilized at plant (Fert) and control trees (No).

As it turns out, there is a statistically significant effect of fertilizer on the June SPAD values.  However, this effect essentially disappeared by the time we re-assessed the trees three weeks later.  Here’s the final version of the data as it will appear in my ASHS talk tomorrow.

This brings up another issue we face in this kind of work; statistical significance versus biological or practical significance.  The ‘Fert: p<0.01’ on the slide indicates there is a 99% probability that the difference in the mean SPAD values between Fertilized and Non-fertilized trees on June 17 is not due to random chance or error.  But as the leaves continue to mature this effect essentially disappears.  Could the early season boost in nutrition be enough to give these trees an edge in the long run?  Possibly, but I wouldn’t say likely.  To date we have not seen any effects of fertilizer on growth but it’s still relatively early in the game. Tree growth is cumulative and effects that may be too subtle to detect early on may turn out to be significant later on. Stay tuned. 

Neon for your garden

Was wandering through Target on Monday for the first time in months.

Helloooo!? The 80’s called and wants its neon crap back.

Didn’t care for it then and certainly don’t care for it now. Though there is the increased safety factor of being highly visible at all times, whether in sunglasses or underwear.

But never mind my lack of style.

It made me think about a few plants that, if the light is right, certainly display that glowing, saturated color, found in the “Astro-Brite” pack of copy paper usually reserved for yard sales and such.

Close to dusk, the Kniphofia uvaria ‘Echo Mango’ in our garden stands out from 100 yards away.  Bred and selected by Richard Saul of Atlanta’s ItSaul Plants Inc., it is one tough perennial, taking heat and humidity with aplomb.

My experience has been one big early summer flush of blooms, with some significant reblooming until frost.  Best in full sun, it’s also drought tolerant and cold hardy to USDA Zone 5. It doesn’t get whopping huge like some other Kniphofia do – stays a nice manageble size, topping out at 3′ to 4′ tall.  ‘Echo Mango’ (or any other Red Hot Poker) adds a terrific bit of vertical interest to an otherwise mound-y mixed border.  Best with fellow warm colors. Pink, not so much.

‘Echo Mango’ = glowsticks!
Achillea ‘Paprika’ doesn’t go so well with it.  Mental note to relocate it in fall.

You can almost hear the sound of space lasers…
Eeee-yoooooo-eeeee-yoooooo…or maybe that’s just me.



Brace yourself

The photo below (graciously sent to me by former MSU Extension Educator Jennie Stanger) graphically illustrates the importance of removing ALL staking and supporting materials from trees once they are established.



Just a matter of time (Photo: Jennie Stanger)

In this case the stakes were removed but the strapping material was left around the tree.  Since this is a spruce, Jennie supposes no one wanted the prickly job of wading into the center of the tree to take off the strap.  Eventually the trunk was girdled and when the area recently experienced some heavy thunderstorms, the weak spot on the tree was exposed.



Stately evergreen to mangled mess (Photo Jennie Stanger)

As a general rule we recommend that all staking and support materials are removed within two years, preferably one year.  This type of damage is one of the prime reasons: after two years who is likely to remember that there is still strapping left on the tree?

The heartbreak of ‘Carrot-top’ syndrome

The perk of participating in a blog is you get a platform to vent on your pet peeves.  Recently I’ve seen several classic examples of ‘Carrot-top’ syndrome.  No, I’m not talking about the red-headed comic; though he tends to annoy me too.

Annoying Carrot-top #1.

The ‘Carrot-top’ I’m referring to occurs when white pine trees are sheared as Christmas trees but then planted as landscape trees.  The typical result is that the side and lower branches remain suppressed while the terminals go crazy.  I’m not sure why syndrome occurs in white pines and not other trees; it may be related to vigor of white pines and how hard the growers have to shear them to keep them in shape.


Annoying Carrot-top #2.

I love my friends in the nursery and Christmas tree industries and they work hard to grow quality trees, but this is one practice I’d like to see end.  And, to be fair, they are giving customers what they want.  If we set up a survey at a garden center and placed  a 7’ sheared white pine next to a 7’ white pine that had been minimally pruned, 19 out of 20 people would take the tree that had been sheared to look like a Christmas tree.  However, this is truly a case where less is more.