Upside-down growing

I was poking through old photos and came across this oddity:upsidedowntrees

What you are looking at is Japanese maples (Acer palmatum) being grown hanging upside down. I saw this year ago at a nursery in Japan. (You are also probably looking at a disaster of girdling roots in those tiny plastic pots, but that’s another topic) When I asked about them, I was told that they are weeping forms, and grown this way temporarily before being planted in the ground right-side up.
Looking at the image, it makes me think that the particular variety grown here might have a mutation that makes them negatively gravitropic, and so respond to the pull of gravity in the opposite way a normal plant would. (For more on that see my earlier post on gravitropism in corn) Growing them upside down would allow them to produce a fairly normal branching pattern, and then once plants, new growth would, presumably, cascade down from the established trunk and stem.
Anyway. That’s your oddity for the day.
Joseph Tychonievich

Trash or Treasure?

You’ve probably heard certain plants dismissed as “trashy” –  but what does that mean?  We have a delightful Magnolia macrophyla in our campus garden – with huge foliage, creamy blooms, the native factor, etc., it draws all kind of attention. So I’d hesitate to call it trashy. But the autumn leaf drop clutters the ground with leaves the size of a sheet of legal paper.  They aren’t rake-able, or really mow-able, have to gather by hand into “sheaves”.  And there’s a LOT of them.

Here’s another example:

We plopped a 3-gallon Koelreuteria bipinnata (many common names, such as Chinese Flame Tree, Bougainvillea Golden Rain Tree, etc). into one of our home perennial borders a few years ago. As Dirr notes, it started out “beanpole-like in youth” but has grown into a nice vase shape. It hit puberty last year, with a smattering of flowers and fruit. This year has been a different story – I swear it doubled in size; and judge for yourself its full-on adulthood:

KPblooms

Late August and early September brought huge panicles of yellow flowers – eye-popping for us, and a late-season bounty of pollen and nectar for our honey bees (and every other bee and wasp in the area). You could hear the canopy “buzzing” from several yards away.

The yellow petals then fell away, carpeting the grass and part of our deck. It their place developed shrimp-pink, papery capsules.

KPpodshabitI cut one of the capsule-filled branches off; and a month later everything is still pink and intact in a vase of water. I also noted each of three capsule sections bears one dark round glossy seed. Uh-oh. That’s a lot of seeds.

KPpodsWith our first freeze, the leaves fell – in big chunks consisting of a tough foot-long petiole and a bunch of leaflets. My mower didn’t do a good job chopping them up – ended up having to rake and move to compost pile. What the mower DID do was fling the papery capsules far into other beds.

KPtrashFlashy? Yes.
Trashy? Yes.
Invasive? Not sure yet. Will report back if seedlings appear!

Comments welcome – tell us about your favorite “trashy treasure”!

A Resilient Citrus Tree Rebounds

Cit3Spring1

Sad Citrus

The last two winters have been pretty brutal on my citrus trees.  Their winter home is the enclosed, but unheated, south facing entrance foyer.  Usually, this is a perfect spot.  Sunny, and with temperatures usually in 45-60 degree range.  But when the polar vortex brought record cold to the Mid Atlantic region back in February, they were hit hard, and I had my doubts that this 13 year old specimen would survive.

Cit3Fall1

Happy Citrus

But it bounced back pretty well, after a season in the sun, so I figured it should be rewarded … I’d give it a new home, replacing its split container … and document the process here.

process1

Prep Area

drill

Drainage Holes Drilled

Process2

Whew! No Pebbles in the Bottom!

Parsley

Rescued Parsley

girdle1

Uh Oh, The Dreaded Circling Root.

girdlecut

Snip Snip

DoneChips

Wood Chip Mulch, of Course

DoneDone

Voila!  Ready to Move Inside

 

Top Ten Trees and Shrubs with Great Fall Color

 

Sugar maple (Acer saccharum) in full fall color
Sugar maple (Acer saccharum) in full fall color

As promised in my Sept. 9 post of “The Science Behind Fall Color”, I would address trees and shrubs with outstanding fall color. It was hard limiting it to only ten trees and ten shrubs, since I found 5 common shrub species of maples alone, so I cheated a bit and grouped the maples, oaks, etc. into one group so that my list was not entirely all maples.

'Robin Hill' apple serviceberry (Amelanchier x grandiflora 'Robin Hill')
‘Robin Hill’ apple serviceberry (Amelanchier x grandiflora ‘Robin Hill’)

I have seen the below plants with reliable fall color in northern, southern and eastern landscapes. These plants “light” up the landscape in autumn. For outstanding, long lasting autumn color, plant the below trees and shrubs with herbaceous plants which bloom in fall such as asters, mums, sedums, monkshood, toad lilies, and Japanese anemones. Do not forget ornamental grasses with their showy seed heads extending the season of color and texture.

Sweet birch, cherry birch (Betula lenta)
Sweet birch, cherry birch (Betula lenta)

We used to recommend ash for fall color, but not any more due to emerald ash borer. Japanese barberry and burningbush are tops for fall color, but both species are highly invasive and not recommended. There are more plants with great fall color than the ones below. I would love to hear your favorites!

 

Top 10 Trees for Fall Color

1) Black gum, sour gum, tupelo (Nyssa sylvatica), orange-red, scarlet to purple, outstanding

Black gum, sour gum, tupelo (Nyssa sylvatica)
Black gum, sour gum, tupelo (Nyssa sylvatica)

2) Maples, especially:

Sugar maple (Acer saccharum), bright yellow to orange-red

Red maple (A. rubrum), yellow, orange-red to bright red

Freeman maple (A. × freemanii), yellow, orange-red, red to reddish-purple

Paperbark maple (A. griseum), dark red to bronze

Japanese maple (A. palmatum), orange, red to purplish-red

Korean maple (A. pseudosieboldianum), deep orange to reddish-purple

Three-flower maple (A. triflorum), orange

Full moon maple (A. japonicum), yellow-orange to scarlet-red

Moosewood, striped-bark maple (A. pensylvanicum), bright yellow

3) Ginkgo (Ginkgo biloba), bright golden-yellow

4) Thornless honeylocust (Gleditsia triacanthos f. inermis), bright golden-yellow

5) Quaking aspen, trembling aspen (Populus tremuloides), bright yellow

6) Oaks, especially:

White oak (Quercus alba), dark red to wine

Red oak (Q. rubra), red to russet

Scarlet oak (Q. coccinea), red to scarlet

Black oak (Q. velutina), dark red

Scarlet oak (Quercus coccinea)
Scarlet oak (Quercus coccinea)

7) Apple serviceberry (Amelanchier × grandiflora), yellowish-orange to red

8) Buckeyes, especially:

Yellow buckeye (Aesculus flava), golden-yellow to orange

‘Autumn Splendor’ buckeye (A. × arnoldiana ‘Autumn Splendor’), deep, burgundy-red

‘Homestead’ buckeye (A. × marylandica ‘Homestead’), orange-red

9) Birch, especially:

Yellow birch (Betula alleghaniensis), bright yellow

Sweet birch, cherry birch (B. lenta), bright yellow

Paper birch, canoe birch (B. papyrifera), yellow

10) Yellowwood (Cladrastis kentukea), bright yellow to gold

 

Top 10 Shrubs for Fall Color

1) Large and dwarf fothergilla (Fothergilla major and F. gardenia), yellow-orange to red, outstanding

Large fothergilla (Fothergilla major)
Large fothergilla (Fothergilla major)

2) Common and vernal witchhazels (Hamamelis virginiana and H. vernalis), bright yellow to golden-yellow

Vernal witchhazel (Hamamelis vernalis)
Vernal witchhazel (Hamamelis vernalis)

3) Virginia sweetspire (Itea virginica), dark reddish-purple

4) Black and red chokeberries (Aronia melanocarpa and A. arbutifolia), red-orange, wine-red to purple

Black chokeberry (Aronia melanocarpa)
Black chokeberry (Aronia melanocarpa)

5) Sumacs, especially:

Shining sumac, winged sumac (Rhus copallinum), bright red to scarlet

Prairie Flame® shining sumac (Rhus copallinum 'Morton')
Prairie Flame® shining sumac (Rhus copallinum ‘Morton’)

Staghorn sumac (R. typhina), orange to scarlet

Smooth sumac (R. glabra), orange to scarlet-purple

Fragrant sumac (R. aromatica), orange, red to purple

6) Oakleaf hydrangea (Hydrangea quercifolia), reddish-orange to wine

7) ‘Tor’ birchleaf spirea (Spiraea betulifolia ‘Tor’), orange to reddish-purple

8) Viburnums, especially:

Withe-rod viburnum (Viburnum cassinoides), orange-red, crimson to purple

Blackhaw viburnum (V. prunifolium), reddish-purple

Arrowwood viburnum (V. dentatum), depends on cultivar, yellow, red to purple

American cranberrybush viburnum (V. opulus var. americanum, formerly V. trilobum), yellow to reddish-purple

Doublefile viburnum (V. plicatum f. tomentosum), wine-red

‘Wavecrest’ Siebold viburnum (V. sieboldii ‘Wavecrest’), red to burgundy

9) Cranberry cotoneaster (Cotoneaster apiculatus), deep reddish-purple

Cranberry cotoneaster (Cotoneaster apiculatus)
Cranberry cotoneaster (Cotoneaster apiculatus)

10) Virginia rose (Rosa virginiana), deep reddish-purple

 

 

Laura Jull, Ph.D.

a.k.a.: The “Lorax”

Bad power line pruning

Driving home today, I saw this lovely sight:

powerlinepruningOur local utility company has been busy butchering trees around the power lines.

Every plant person I know complains about this, but I honestly don’t think there is much hope for a change. Power companies don’t want limbs falling on the electric cables during storms, and they’re not likely to start spending money to hire real arborists to do the pruning.

What I really wish is that people would start thinking a little more before putting in a tall tree directly under electric lines. I’m sure these went in as cute little babies, I know it can be hard to visualize what a small tree will grow into, but we do really need to do a better job of it. If you are looking to plant, take the time to look up the tree in question and see how fast it is going to grow. Google will usually tell you, and if you are planing conifers, the American Conifer Society has an amazing website which will tell you the growth rates in inches per year of just about any conifer you can imagine. Check it out, and do the math, and see just how fast that little spruce is going to be causing problems before you start digging holes.

Little ball of horrors

One of the great things about doing a multi-author science blog is that there will be topics about which colleagues will disagree. One of those topics revolves around the best way to prepare woody rooted plants (trees and shrubs) before planting them. This is an area in arboricultural science that is evolving. A search through our blog archives will find many of these posts and for convenience’s sake I’ve linked one from each of us here.

From Jeff (2009)
From Bert (2014)
From Linda (2013)

Rather than belabor the points that Jeff, Bert and I have already made in our posts, I think I can sum up our major difference here: I like to bare-root trees and shrubs completely before planting (so I can correctively prune all flawed roots) while Bert and Jeff prefer a less invasive approach. What we do agree upon, however, is the deplorable condition of the roots of many trees and shrubs that end up in the nursery. Because I do practice bare-rooting trees, I thought I’d use today’s post as a rogue’s gallery of trees that should never have made it to the retail nursery. (All of these trees were ones that I bare-rooted and root-pruned myself before planting – and all are thriving.)

Ginkgo "knee" root
Ginkgo “knee” root
Interlocking redbud roots
Interlocking redbud roots
Junky Japanese maple
Junky Japanese maple
The duct tape around the trunk is where the burlap bag began. While the roots are in pretty good shape, only root-washing could find the root crown of this tree.
The duct tape around the trunk is where the burlap bag began. While the roots are in pretty good shape, root-washing revealed the root crown of this tree (which the “at grade” part of the tree) 10″ below the top of the bag

The Science Behind Fall Color

Japanese maple (Acer palmatum) in full fall color
Japanese maple (Acer palmatum) in full fall color

In many parts of the U.S., particularly the northern U.S., we are blessed each year by nature’s display of bright color dotted through the landscape. Fall color of leaves at the end of the growing season provides a remarkable encore in the landscape. There are many trees and shrubs with great autumn leaf color and I will address some of them in my next week’s post, but this week, I will talk about what actually happens inside the plant during autumn.

Plant Pigments

As the days get shorter and temperatures start to cool, particularly at night, the season changes from green leaves into a kaleidoscope of yellow, orange, red, purple and bronze shades. There are a variety of factors that interact and play a role in determining how colorful the display will be. Plant leaves contain several pigments that determine the color that will appear and variations arise when different concentrations of pigments are combined in the leaf.

Eyestopper™ Amur corktree (Phellodendron amurense 'Longenecker'), a male cultivar with bright yellow fall color
Eyestopper™ Amur corktree (Phellodendron amurense ‘Longenecker’), a male cultivar with bright yellow fall color

Chlorophyll is the green pigment in leaves. This critically important pigment captures the energy from the sun and uses it to change water and carbon dioxide (CO2) into oxygen and sugars (carbohydrates), i.e. the plant’s energy source for growth and development. In autumn, chlorophyll breaks down faster than it is produced, revealing the other plant pigments and their colors.

A cutleaf weeping Japanese maple (Acer palmatum) bright orange fall color
A cutleaf weeping Japanese maple (Acer palmatum) bright orange fall color

Carotenoids are responsible for the yellow, orange and a few red pigment colors. This pigment is always present in the leaves during the growing season, but the colors become more evident as the chlorophyll breaks down in the leaf. In addition to providing us with a beautiful display, carotenoids protect leaves from harmful byproducts of photosynthesis. Since carotenoids are always present in leaves, yellow, gold and orange colors are least affected by the weather.

Anthocyanins are responsible for most of the red, pink, and purple colors we long for in autumn. Sugars in leaves accumulate as active growth slows down in autumn permitting the production of anthocyanins. These colorful pigments act as an internal sunscreen to protect the photosynthetic system allowing plants to recover nutrients from the leaves more easily as the temperatures decline. What about plants that have no anthocyanin pigments? These plants are usually more resistant to damage from bright light so they have no need to produce these protective anthocyanin pigments.

Tannins are not considered an actual plant pigment, but are responsible for some of the tan and brown colors we see in oaks and beeches in the fall.

Why Do Leaves Change Color?

During the summer, most of a plant’s nutrients are located within the leaves. The shortening of day length and cooler temperatures, particularly at night, signal the plant to begin preparing for winter by transporting carbohydrates (sugars) and mineral nutrients from the leaves to stems and roots for storage in the plant to be reused the following spring. A layer of cells at the base of the leaf stalk (petiole), called the abscission zone, gradually closes off the flow of sugars and minerals into and out of the leaf. In a process called senescence, chlorophyll breaks down causing the leaves to change color and eventually fall off the plant.

Variability of Fall Color and the Role of Weather

Many factors play a role in determining when fall color occurs and the intensity of the color. We cannot predict each summer how the autumn leaf color will be in the landscape. For example, peak (best) fall color can shift by as much as two weeks ahead or behind the normal time peak color occurs year to year based on the weather.

Plant Health and Moisture Levels

Plants that are in transplant-shock (newly planted), drought stressed, nutrient deficient or suffer from insects or diseases may have poor fall color or the exact opposite; they may have better fall color due to increased production of red pigments. Good soil moisture levels throughout the growing season followed by a dry fall can improve the intensity of fall color. On the other hand, excessively wet or drought conditions can cause poor color development. Drought conditions can cause leaves to dry, curl and drop before fall color has sufficiently developed, especially on newly planted material. However, moderate drought conditions may actually improve fall color development in some species, though these same plants may suffer during winter and have dieback apparent in spring.

Temperature, Light Levels and Mineral Nutrition

Cool, dry, sunny fall days with cooler night temperatures stimulate anthocyanin production resulting in bright reds and purples. In contrast, very warm autumn weather may reduce the production of these pigments. During unusually warm autumns, plants may accelerate fall color development, shortening the time leaves remain on the tree or shrub. Early, hard frosts may also severely damage leaves, arresting further fall color development before the brightest colors are revealed. Sufficient sunlight is required for leaves to produce the best coloration. Plants growing in dense shade will usually fail to develop the intense red and orange colors we have grown so fond of each autumn. High soil pH and deficiencies of the various essential mineral nutrients, such as nitrogen, phosphorus, magnesium, iron and high levels of the non-essential element sodium can all affect the intensity of color change in leaves. High sodium soil levels, most likely due to excessive road salt (NaCl) application the previous winter, not only stresses plants and prevents proper water uptake, but also can negatively affect autumn leaf color.

Genetics

Of course genetics play a key role in the intensity of fall color development. This is why some seed produced trees in the forest have great fall color, while seedlings from the same tree may have less intense or even no fall color. This is where plant cultivars come into play. A nursery person will select plants demonstrating superior fall color, improved cold hardiness, increased pest resistance, better growth form, etc. These superior plant choices will often have a cultivar name associated with it. For example, seedling grown red maple (Acer rubrum) will display a range of fall color from green, yellow, yellow-orange, orange, orange-red, red and purple. As gardener, we tend to choose what we like, mostly the orange, red to purple colors. If the plant is not already in commerce, the grower will select the best seedlings for fall color and vegetatively propagate and grow those particular seedlings, offering these new selections to other nurseries or garden centers. It is a win-win for both the nursery and the gardener!

An unknown cultivar of red maple (Acer rubrum) with uniform fall color
An unknown cultivar of red maple (Acer rubrum) with uniform fall color

Laura Jull, Ph.D.

a.k.a.: The “Lorax”