Colorful, elegant, refined, dramatic, sophisticated, and playful: garden designers gather these sorts of accolades and more for their summer annuals displays.  But they don’t “own” the patents on beauty.  Making a beautiful and effective groupings of annuals is entirely within reach of even humble ol’ you and me.

Let’s look at three basic “tricks” used by even the most intuitive of professional garden designers, and then illustrate them with some container plantings now on display in Cleveland Botanical Garden’s Sun Patio in the new Inspiration Gardens.  When we’re done, I think we’ll choose our summer flowers with brighter, keener eyes.

“One” is to follow the color wheel, and choose a palette for flower and leaf.

Red-Orange-Yellow-Green-Blue-Violet; that’s the color wheel.  Easy.  Now, “Google” a color wheel.  Colors run in the R.O.Y.G.B.V. sequence around the wheel.  What’s directly across from, say, red?  Green…and that makes complementary dyad with red.  Starting with red, what other two colors are equidistant around the wheel?  Yellow and blue…and they’re a complementary triad with red.

Any dyad or triad selected from the color wheel like this is a guaranteed match!

Be careful with a few things.  If in doubt, don’t mix “saturated,” or intense, colors with pastels.  For instance, a pastel pink impatiens with bright yellow marigold is a color clash.  Also, if in doubt, don’t mix warm and cool colors.  Warm (towards the sun) and cool (towards the moonlight) can work together, but avoid them until we are sure of our "eyes."

Use white flowers to frame or “dot” your color palette; white often adds informal cheer, and dilutes color intensity.  Use black/dark foliage to frame color palette; black adds drama/elegance and strengthens color intensity.

“Two” is to consider plant structure and form, and choose harmonious suite of shape and texture.

Use leaf variety to accentuate our color choices, and to help give our containers gesture and flow.  Whaaat?  Look at the accompanying pix.  Dark, broad leaves inflame the greens and the reds; ultra-violet leaves rise dramatically like midnight  flames.  That is gesture and flow.  If all leaves in a container are similar size/shape, they look "busy."

“Three” is to remember plant needs, and to choose plants that grow well together.

This is easy with annuals.  Most annuals like full sun and plenty of water.  Pelagoniums (geraniums), verbenas and marigolds are a few dry-land rule-breakers that come to mind.  For instance, pelargoniums develop yellow leaves if heavily watered alongside canna.  And—ahem—as we can see in the pic, I broke this rule on the Sun Patio!

Color acts on us physically, biologically, and psychologically. Complexity!  Harmonious interaction of texture and form have been debated surely since the days of Lascaux Cave Painting, and the discussion is still lively today.  That’s right, our One-Two-Three design rules are a beginning…without end.

And please visit our Sun Patio to see some well-designed summer annuals plantings.  Colorful or dramatic, or both?  I do know they set the garden afire!

Posted by Mark Bir

P.S.: I’ll make this a continuing series…if you show interest.  Hey, lemme know.

It’s a simple enough job to sit down at my keyboard and tap out another profile for one of our garden plants. The resultant blog would be tidy, professional, factual, and a total bore. What, with access to a library full of plant books upstairs and Google at my fingertips, to write such a piece I would feel like I am plagiarizing all sources in one swoop. It is a written form of vegetative propagation, perhaps? “What’s the point of being redundant,” he repeated.

So with this week’s (er—month’s) blog entry, I am going to attempt to not-so-much brief you, dear reader, on a common flower growing here at Cleveland Botanical Garden, as to put that plant into specific and particular context.

Meet ‘Mandarin Twist.’ (Shake hands here.) Mandarin Twist is a brilliant orange-blooming cultivar of the so-called calendula or pot marigold, Calendula officinalis. This once-native of the Med is classed as a hardy annual, which in Cleveland means that it behaves pretty much like a regular old annual. Start it from seed in a cold frame—easy—about April Fool’s Day, and plant it outside a week or two before Memorial Day. A fortnight after an early planting, ours began to bloom…and bloom and bloom. Now, pot marigold is widely reputed to Peter out when the temperature soars. But even with our recent July fire days, our Mandarin Twist has stayed true to the colorful course. What have I done to aid and abet? I deadhead ours with snippers down to the next leaf nodes once a week. A little fertilizer high in the last two numbers every third week (or-so), some supplemental water recently, and that’s been it for care. No bugs, no rusts or molds or other phyto-FUBARs have found ‘em here. Flowers galore.

It’s in the aster family, and sets copious seed, so if you want to be a seed-saver, just let some of the August blooms stand for seed. Might put mesh bags around ‘em soz they don’t make birdfeed. Although it is a cultivar, Mandarin Twist is not too far removed from its wild progenitors, so I’m betting they’ll breed near to true, with a few interesting variations popping up in your seed flats, as well.

Inspect Mandarin Twist at Cleveland Botanic Garden in the sunken garden between the library and the Japanese Garden. Find it rising in a mass from behind the central stone bench. Can’t miss it, like sparks issuing from a fire. It is framed by dramatic contrasts that punch-up the orange heat: 1) a low foreground of across-the-color-wheel black sweet-potato vine and purple alternathera (pow!); 2) bold “N” exotic canna leaves like stage curtains to either side (bif!); 3) inky pools of shadow in the background (wham!).

Calendula is doubtless a common annual, but one that I feel is underused in our fair city. Go orange, give ‘Mandarin Twist’ a try. BTW, the name “Calendula” has a curious etymology. But I’m not gonna tell you…gotta Google it yourself!

Posted by Mark Bir

Some scientists predict an increase in natural disasters as a result of global warming. But somehow I think something else is responsible for all the volcanoes I see erupting in my neighborhood.

‘Volcano’ is the term coined for that mound of mulch that folks pile around a tree this time of year. Even though all the credible references advise against this, it somehow seems to be very popular. I drive through developments in which landscapers have generously heaped the mulch into a nice pyramid around every tree.

After spending a fair amount of money on new trees, you would think a homeowner would want to protect that investment. One of my neighbors recently built a series of volcanoes around the trees throughout his yard. It looks kind of cool, but just like Mount Vesuvius, these volcanoes can be deadly. That pile of mulch heats the base of the tree and holds moisture up against the bark. Not only does this encourage pests and diseases, but the tree responds by sending out new roots into that pile of mulch. Instead of spreading outward, these new roots grow inside the pile and over time can girdle the tree as they expand.

The International Society of Arboriculture recommends mulching tree root zones to help retain moisture in the ground and act as a weed barrier. But to avoid decay, disease and pests, ISA calls for mulch to be kept one to two inches away from the base of the tree. So a good gardening practice after mulching is to go back and sweep away any that might have piled up on the tree flare.

The trees will thank you.

Or What the Heck Did I Plant?

I love old-time gardeners. They are a wealth of knowledge through decades of trial and error. One thing is for sure: gardening is a learning process. Smart gardeners track what was planted, what was successful, what failed. The challenge for me is how to record and store this hard-won information.

I always give a little chuckle when I see bookstores carrying garden "journals." The idea is to sit placidly in your garden, sipping a tall glass of lemonade or ice tea, writing what gardening activity you just completed. Some journals are just lined notebooks with a nice cover. Other journals are more organized, for instance, by seasons. Now, if you are like me – and I sincerely hope you are not – you are extremely busy, and time to record what you planted, what you removed, or what weather conditions just experienced is not available. Who has the time, right?

It’s raining today. And cold. It makes me want to nap. But it is also so beautiful outside right now that it makes me want to garden. I think the colors outside are amazing during this kind of weather and I spend a considerable amount of time staring out windows during spring showers.  I may not want to admit that during the work day, but it’s the truth.  So considering the weather, rain gardens come to mind. If you have an area in your yard that regularly holds standing water, you may want to consider installing a rain garden. Good old Wikipedia says that “a rain garden is a planted depression that allows rainwater runoff from impervious urban areas like roofs, driveways, walkways, and compacted lawn areas the opportunity to be absorbed.” A rain garden prevents soil erosion, decreases the water emptying into storm sewers and looks great in the process. The Cuyahoga Soil and Water Conservation District has fantastic resources on their website for rain garden installation and has a kit with all the plants needed for a 100 square foot garden available for purchase. The manual from their website is the best I’ve seen on rain garden installation.  In our library, we have a book called Rain Gardens: Managing water sustainably in the garden and designed landscape. (Why do all books nowadays have to have such long titles? What gives?) In looking through this book, I realize that I need to be careful about information I take from books. This is potentially a very useful book. In Great Britain. The two authors hail from the UK and give many examples and pictures from rain gardens in Europe, which is all fine and well and good. My problem lies in the chart of rain garden plants at the back of the book. At first, I’m all excited – I love lists! And they tell me exactly what I need to know without a ton of reading. But then I see they recommend purple loosestrife, even noting that it can be incredibly invasive. So why are they recommending it? I would never, ever recommend planting purple loosestrife so this book’s value and credibility decreases tremendously in my opinion.  Lastly, we have just broken ground on our very own rain garden here at the Garden which will be complete by the end of May. It is located adjacent to the Woodland Garden and will be a great visual enticer for you to install one of these beauties in your own landscape. This rain garden is being installed as I type this; stop by the check it out, or stay tuned to this space for enticing documentation of this important new garden.

          Like much of the rest of the world, I love strawberries. Very few things that taste as good as strawberries are also good for you. When I was a kid, I used to go strawberry picking with my family, and I would often eat a few berries right off the plant. If I knew what I know now about strawberry production, I would have waited for the strawberries to get a good rinsing before I ate them. Strawberries often receive repeated doses of pesticides, mostly fungicides, and are on the list of the twelve fruits and vegetables with the most pesticide residue. These twelve fruits and vegetables are often referred to as the ‘dirty dozen." You can see the rest of the ‘dirty dozen’ and also the ‘clean 15′ here. Even scrubbing and rinsing cannot remove all pesticide residues from the soft skin of strawberries, but it can remove a good majority.

        The problem with farming strawberries is that they don’t grow well in the same spot for too long. The many diseases and insect pests that plague strawberries will begin to accumulate in the soil, reducing yields and increasing need for pesticide sprays. Many commercial strawberry growers will use harsh pesticides like methyl bromide to completely sterilize their soil in order to keep growing strawberries.  Methyl bromide is a highly dangerous gas that is injected into the soil underneath plastic tarps killing all living organism in the soil. It’s is also an ozone depleting gas. It’s use has been mostly phased out by the EPA, but it is still used for a small number of crops like strawberries.  Methyl iodide, an equally dangerous fumigant that is highly carcinogenic, was recently approved by the EPA and is being used in some places as a replacement for methyl bromide. Its use is currently being debated in California where it is currently not approved.

       Since it seems to take a lot of serious pesticides to grow strawberries on a commercial scale, you might think it would be too difficult for the average gardener to grow. In fact, strawberries are quite easy to grow and are considered by many home gardeners to be one of the easiest fruit crops to grow. The problem of soil-borne diseases and pests can be easily solved for a home gardener using crop rotation. Strawberry plants tend to lose their vigor after about 5 years and need to be replanted. Instead of replanting strawberries in the same spot, try planting them somewhere else in the garden. Amend the former strawberry bed with organic matter and plant crops or flowers that are not susceptable to strawberry pests- avoid tomatoes, peppers, and cucurbits. Another easy solution is growing strawberries in pots. Strawberries do very will in pots, and the soil can easily be changed when replanted.

       When it comes to strawberries and other members of the "dirty dozen," it may be best to grow your own.  If you can’t grow your own strawberries, try buying organic first or support local farms that use crop rotation techniques to reduce pesticide needs. Also, be wary of buying strawberries out of season as they often come from other countries where even more pesticides are used. It would be a shame to limit consumption of such a delicious fruit that also has so many health benefits.

Posted By Nate Tschaenn

Tale One: Big Tree, Big Axe.  Cleveland Botanical Garden has a row of maturing, healthy Norway maples (Acer platanoides) growing along East Boulevard.  And we are cutting them down.

Actually native to Norway and across northern Europe, the Norway maple has a detailed association with humans.  If never a lumber tree, it has long been valued for fine carpentry and horticulture.  In early 1700s Italy, Antonio Stradivari probably made the back boards for his supreme violins from Norway maple.  By the mid 1700s Norways had crossed the Atlantic to appear in Colonial seed lists; there is a 1756 record of one being planted in Philadelphia.  Norways were popular in 1800s New England as garden fancies (curiously, all our trees came from English nurseries, where Norway maple is non-native, so we have no wild provenance on  U.S. stocks).

But it took Dutch elm disease of the 1930s to bring the Norway maple to its current prominence in the northeastern U.S.  This disease that devastated our native American Elm (Ulmus americana) created a huge void in our street tree population, a void that was filled by existing nursery stock in the form of the Norway.  And it was a good elm substitute, for it was found to be easy to commercially re-propagate in a hurry, to transplant well, to grow vigorously on site, and to have tremendous tolerance of urban environments.

But the Norway also makes impenetrable canopy shade, throws copious fertile seed, and chemically inhibits competing seedlings. This suite of traits both “good” and “bad” soon helped the Norway become—you guessed it—a woody weed.

So here at the Garden, we had three Norway maples removed (I can’t say “felled” since they were hoisted up from their stumps and craned out of the garden) the week before last.  In the coming years, more will be removed.  And we already have a plan for the sunny slope they are leaving behind.  Our Woodland gardener has selected a swath of flowering shrubs, small trees, ferns and wildflowers to grow and thrive in this space.  The emphasis is on native plants, but there are exceptions; the design is naturalistic, but with an artistic gleam.  So watch this space with some anticipation.  Coming soon are flame azaleas and rosebay rhododendrons, native silverbell and spirea, hay-scented fern and fragrant sumac; a hillside painting in the sunshine.

Look around you.  If you have an ornamental maple in your yard with burgundy, bronze or chartreuse foliage, it is a Norway hybrid.  I don’t loathe the Norway so much as respect its potential.  Like all weeds, to me it is half-terror, half-teacher.

Tale Two: Big Tree, Small Axe.   Cleveland Botanical Garden has a nice Chestnut Oak (Quercus prinus) at the edge of the Restorative Garden, and right now it is dropping twigs damaged by a girdling beetle.

The flat-headed longhorn oak girdling beetle (poss. Oncideres quercus) probably won’t kill the tree.  But over the past few years of infestation it has already disfigured its twigs, by inducing hundreds of haphazard, zigzag re-growths.  And I have been taught by experience that one tree stress often invites others, which add up to sometimes deadly arithmetic.

This beautiful little creature wears wing covers that look as if they are made from hammered lead, and sprouts segmented, elegantly curved antennae that extend from flat head halfway to pointy tail.  It leads a peculiar and particular life.  The little twig tips littering the ground today were fashioned last autumn into nursery chambers by the adult beetles.  The adults chewed “girdling” rings into their twigs, and then laid a few to a few dozen eggs under the bark of each of their outrigger twigs.   The adults soon died, but their eggs hatched within the twigs, and spent the winter as larvae, nestled and safe up in the tree.  With this spring’s winds and rain, the girdled—and killed—twigs are now snapping free from their moorings, and falling to the garden floor.  And it is down here that the oak girdling beetle larvae begin to feed for a few weeks, eating their nursery walls.  They then pupate, again in their original twig chambers.  By mid-summer, the flying adults will hatch, eat some green wood, mate, and girdle more living chestnut oak twigs to complete their annual life cycle.  I will collect some twig tips, keep them contained, and see if I can capture one of the hatching adults this summer.  If successful, I will post pictures here.

Common in Ohio, I see evidence of the oak girdling beetle every year in chestnut oaks, white oaks (Quercus alba), and bur oaks (Quercus macrocarpa), too.  Bur oak twigs snap off a few months from now; is the wood perhaps more durable, or does bur oak bear a different species of beetle?

If you have girding beetles living in your oak, don’t fret.  Tend to the tree’s general health and it will withstand the infestation.  Don’t compact your oak tree’s soil or cut its roots, and don’t mulch it too heavily.  Prune damaged wood that might invite secondary disease.  And collect and destroy all the fallen twigs, so removing the next generation of beetles in the process.

Oaks have co-evolved along with a host of voracious native insects.  For their half of this never-ending pull-and-tug, oaks manufacture an array of tannins and possibly lignins for chemical defense. Nevertheless, an oak un-blighted by apple gall wasps, oak leaf rollers, or girdling beetles seems unusual to me.  They must be generous trees, and surely the flat-headed longhorn oak girdling beetle is fortunate for this bounty.

There you go: Two Cutting Tree Tales; Or, What I Saw In The Garden.

Posted by Mark Bir 
 

 This world can sometimes be a little chaotic. But there is no reason that needs to spread to your garden. Harmony is the design concept that ties things together. It may be the repetition of colors, shapes or textures or a unifying theme employed throughout the garden. It is an important principle that tells the visitor that the space makes sense and is pleasing to view.

Containers give the gardener a lot of creative options to achieve harmony. They are portable and easily changed out to complement whatever is going on in the beds. Here is an example of tulips in containers that match the display in the bed. This of course was conceived in the fall when bulbs were planted in the bed. The same tulips were also planted in nursery pots and sunk in the ground. This works better than planting them directly into above-ground containers that experience frequent freeze/thaws throughout the winter. The ground insulates them from wide temperature fluctuations and helps them develop in sync with the bulbs in the bed.  In the spring the nursery pots are simply lifted and placed in the containers to provide an arrangement that harmonizes with the display in the bed.

Posted by Bob Rensel

We have a new visitor to the Garden.  But this one has six legs, mandibles and compound eyes, and is most unwelcome.

The viburnum leaf beetle (Phyrrhalta viburnii) is here, and we are in danger of losing much of our flowering viburnum collection to its hunger.  Why is it such a problem?  Because the “VLB” has been introduced inadvertently to North America without any of its natural checks and balances, and so is free to chew its way through our wild and garden viburnums.  Not only that, it comes with a one-two punch, since both the larvae and adults feed on viburnum leaves.

A European native, this inconspicuous brown beetle—1/5” long—was first noticed in Canada about 1947 (possibly it was a hitchhiker on garden viburnums shipped from overseas].  VLB has since been making its way through the east; in 2000, it was verified in western PA and parts of Ashtabula County; by 2008 it was verified in Lake and Cuyahoga Counties.  We found it on some of the Garden viburnums this summer.

What is a gardener to do?  We could slather our viburnums with potent organophosphate insecticides, which would certainly kill VLB, along with all the other local arthropods, good and bad in the same basket.  We could do nothing, be totally organic, let the beetles have their way, and supplant infested viburnums with different flowering shrubs.

Or we could choose a hybrid approach.  If we made the effort to study VLB/viburnum interactions, we might then be able to design a modified organic control plan that selects mechanical and biological controls, but also permits least-toxic chemicals when absolutely needed.

Sounds like a pretty good idea!  Let’s walk through the hybrid “education and action” plan that we made for our VLB infestation.

As these things often go, VLB has learned to favor our smooth-leaved viburnums, especially arrow-wood (Viburnum dentatum), over the hirsute varieties it had back home.  Maybe it’s like eating nectarines instead of peaches? A Garden walk-about confirms this, so we decide to focus on arrow-wood, and simply monitor other viburnum varieties for VLB. This saves us effort and possible pesticide use; if other viburnums begin to show VLB damage, we’ll adjust protocol.

We also decide to provide complete cultural care to all our viburnums, to reduce their overall stress and so help them survive VLB.  This is a simple matter of composting and mulching in spring, and irrigating during possible summer dry spells.

Next, we consider the VLB life cycle, since it will help us discover when the beetle is most vulnerable.  VLB lays eggs by drilling into viburnum first- or second-year branch tips in early autumn; the eggs over-winter under the bark and hatch by early May; the larvae eat leaves, and then crawl down to the soil to pupate by early June; the adult beetles emerge by early July, eat leaves, mate, and complete the annual cycle. VLB presence is  betrayed by two identifying clues: "sewing machine" egg scars on dormant twigs (see photograph); buckshot feeding holes in the leaves starting in late spring.

Well, what is the best stage to arrest VLB?  We decide to go after the eggs, since they’re easy to catch!  A mechanical control method will work.  So, right now in early April, we are tip-pruning egg-laden young twigs from infected arrow-wood plants, and away from their future feeding bushes.  This is a good choice, since viburnums respond well to pruning, and will not suffer a loss of vigor.

In our highest visibility gardens, where viburnums need to be cosmetically perfect, we will forgo tip-pruning, and choose from two chemical control options.  First choice is an April spray of summer horticultural oil, which is essentially liquid candle wax.  Hort oil is topical, smothers the eggs, and does minimal harm to beneficial arthropods. Second choice is granular imidacloprid, a synthetic nicotine that is applied to soil and translocated from the roots to the young leaves, where it kills the feeding VLB.  Used like this, it also doesn’t harm predatory beneficial insects.

We will attempt to get by with just the early spray of benign hort oil.  If this is unsuccessful, next spring we’ll go for the nicotine.

Oil can also kill the larvae, but timing is more finicky.  Killing the adults requires stronger broadcast chemicals, and by their advent it is too late anyway to prevent leaf damage by the hungry spring larvae.

There it is.  We studied the plant and the insect, and used what we learned to pick a suite of smart, safe control methods for our VLB infestation.

There’s a name for this approach to pest control.  It is “Integrated Pest Management,”  or (here comes another acronym) IPM.  Local biological systems are kept intact, to buffer against future pest explosions.  Plants are grown with the grace of their unique nature in mind.  IPM views the garden as a whole, and not merely as a game board of plants vs. enemy insects and diseases.

The threat to Ohio’s wild and garden viburnums is real, and may even prove devastating.  Please monitor your viburnums for VLB damage, and be ready with IPM thinking.  Integrated Pest Management: control the pest without crushing the garden.

—I better get busy, I think I just heard that new visitor calling my name…”CHOMP!”

For more on VLB, check these websites:  http://ohioline.osu.edu/sc195/013.html, http://www.hort.cornell.edu/vlb/html   

 Posted by Mark Bir

Why do we prune woody plants?

We prune them to improve their fitness.  Interior branches are removed to invite more sunlight.  Crossing branches are cut away from their neighbors to prevent rubbing injuries. Weak and failing branches are pruned out to prevent storm damage and discourage disease.

We prune them to highlight facets of their beauty or utility.  Old trunks are lopped from weary lilacs to encourage fresh flowering stems.  Apple trees are thinned to encourage better fruit set.  And spent rhododendron flowers are dead-headed to foster flower development for the next spring.

We prune them to keep them in bounds.  Limbs are taken away from our buildings, shade branches are lifted off of our vegetable gardens, and dangerous branches are cut from electric lines.

We even prune them for art.  Sycamores are pollarded, hawthorns are pleached and dogwoods are espaliered, all here at the Garden.  The Topiary Garden is a fanciful journey through a gardener’s imagination.

All great “whys” and all good gardening practice.  And I got to put them into action last week, when I pruned a row of crabapples here at the Garden.

These particular crabs were originally part of a temporary planting that has now become semi-permanent.  They’d gotten too big for their site, and so I determined to make a few major cuts that would bring them back to scale.  And being clump or shrub crabapples (probably one of the Malus “Zam” hybrids developed in Lake County), they had also become densely tangled with young suckers and small branches and spurs, and too scruffy for their formal setting; so I decided to give them a little secondary pruning as well.

With apple trees, there are at least three established basic pruning styles from which to choose.  We can train apples to have: strong central leaders (the future main trunks); ladders of lateral branches on a few co-leaders; or no remaining central leaders.

I chose to use my major cuts to remove all their central leaders.  Why?  Being shrubby crabs, I felt this protocol best reflected their natural “wild” tendencies, and allowed me to reduce their size without resorting to awkward and unhealthy topping and end cuts. Through this process, they will also receive more interior light, and subsequently fill with flower and fruit next spring.  And with this pruning style, I only needed to make a few center cuts to each tree to achieve a convincing improvement.

In this order, here’s what I did.
1. Stared at each tree for 10 minutes.
2. Decided on the two or three big cuts to make—wait.
3. Removed all root- and stem-suckers (these are crabapples’ bad habits).
4. Double-checked my decisions, and then made those big cuts.
5. Studied the tree for a few more minutes.
6. Removed some secondary branches.
7. Carefully pruned branch tips only where required, following natural branch shapes.
8. Looked at it again. If in doubt about a branch,  I left it for tomorrow!

I pruned these trees during late winter (well, okay—early, early spring) to allow me to inspect them without leaves to obstruct my view.  The penalty is that I removed many set flower buds along with the pruned branches. 

I could also have chosen to prune them just after the flowers fade in late May.  The plants will accept either treatment.  I wanted to shrink them and get them shapely again immediately, so I felt it was a fair trade to accept a lighter bloom this spring.

See the accompanying pictures below to see the whole job in action.  If I did a good job, over the coming months you and I both will get to watch in-person this little row of crabapples fill with light and prosper within bounds. 

Posted by Mark Bir