pruning

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My Review of Decurrent Trees

Just because it’s winter doesn’t mean there aren’t plenty of plants to look at. Deciduous trees and shrubs become particularly interesting during the winter months with their exposed branches and their growth habits made more obvious. The beauty of a tree’s “skeletal” structure is revealed when it’s stripped of its leaves and set against a winter sky. Winter is also a great time to prune certain trees and shrubs (when appropriate), partly because their branches are so easily viewed and “problem” areas readily reveal themselves. Whether you’re observing a tree’s branching structure simply for enjoyment-sake or because you plan to prune, you may find yourself noticing distinct differences in the growth habits of trees. Distinct growth habits can help you identify trees. They can also tell you something about a tree’s environment or growing conditions.

In the book, The Tree, Colin Tudge defines a tree as “a big plant with a stick up the middle.” Sometimes this “stick” runs straight up from the ground to the top of the tree without interruption and is the tallest portion of the plant. Other times, the “stick” reaches a certain height and branches out into multiple “sticks,” each one reaching out in a different direction – some heading more outward, while others continue to reach for the sky. This is the difference between excurrent and decurrent growth.

excurrent growth habit: dawn redwood (Taxodium distichum)

A tree with an excurrent growth habit has one central leader – or single trunk – that reaches all the way to the top of the tree. Side branches occur along the length of the trunk and generally get shorter as they move up the tree, producing a pyramidal or conical shape. Think of a typical Christmas tree. Many conifers exhibit excurrent growth, as do several deciduous trees such as sweetgum and pin oak, as well as aspens and other poplars. When a tree divides part way up the trunk, splitting into several large branches – none of which could be considered the dominant branch – it is exhibiting a decurrent growth habit. Trees that generally fall into this category include elms, maples, oaks, and ashes. The growth habit of a tree is largely a result of its genetics, but plants are known for their plasticity, taking on a wide variety of forms depending on their parentage and their circumstances. Trying to identify a tree based only its growth habit, isn’t likely to yield great results.

decurrent growth habit: oak (Quercus sp.)

The environment that a plant is growing in can have noticeable effects on the form the plant takes. A tree growing up in a forest thick with other trees will typically grow straight up in search of sunlight and will branch out very little until it can get up high enough to do so. That same species of tree growing in an open field might instead branch out extensively at a much lower height, taking advantage of the generous amount of space to stretch its branches out wide. As Tudge puts it in The Tree, “one form for the forest, another for the open ground.” Additionally, things can happen in a tree’s life that will drastically alter its form. If, for example, a storm comes through and breaks off a tree’s central leader, several side branches might grow out and upward to take its place, giving an otherwise excurrent tree a decurrent form. The pruning that humans often do (sometimes unwisely) to trees and shrubs, particularly in urban settings, can also alter a plant’s natural growth habit considerably. These are important considerations to make when assessing the forms of trees.

decurrent growth habit: golden rain tree (Koelreuteria paniculata)

I give decurrent growth habits five stars. No shade on excurrent trees. They’re also beautiful. But while trees with excurrent growth habits have otherwise predictable forms, decurrent trees are full of surprises. Their broad and rounded forms provided by their deliquescent branching structures are endlessly interesting, and their capacious canopies ensure that no two trees are alike.

decurrent growth habit: Malus sp. (I presume)

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The Problem with ‘Yes’ Landscapes

This is a guest post by Jeremiah Sandler. Follow Jeremiah on Instagram @j.deepsea

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I don’t work for a landscape company, nor have I ever worked for one. The company I do work for contracts with these companies to do health care on their landscapes. For example, we scout for insects and diseases, spray pesticides when necessary, make recommendations of proper cultural practices, and fertilize.

Something has been bothering me for the past two years about the landscapes in metropolitan southeast Michigan. Both commercial and residential landscapes have at least two things in common: the same plants, and the same poor management of these plants. The clients have no idea they’re being ripped off.

The landscape companies I have experience with seem to think the homeowner is always right.

The ‘Yes’ Conversation

You want a Colorado blue spruce in humid Michigan? Sure, no problem. Let’s put six trees within 15 square feet. Don’t bother removing the cage and burlap. We also won’t tell you the massive expense you’ll pay in the future to spray fungicides on your spruce to keep it alive. If one dies, we’ll just replace it with the same plant.

You want a green hedge? Boxwoods or yews. They’ll be sheared multiple times a year by our crew of expert (and underpaid and exhausted) workers. At the first sign of new growth, we’ll be there mutilating your plants to ensure that they stay at right angles. You see all of those ripped apart, discolored leaves on your shrubs? Ignore that; plants are meant to be tamed into perfect geometry. Oh, that’ll be an extra charge to spray insecticides and fungicides.

Here’s a list of plants you can get to add to the monotony in your neighborhood: crabapple, hawthorn, cherry, honeylocust, blue spruce, oak, red maple, Japanese maple, pear, white pine, boxwood, yew, hydrangea, arborvitae, burning bush, and wax begonias.

Why is your hemlock tree neon yellow? We don’t know, let’s just replace it. Why is your Norway maple declining? Well, when we planted it, we kept the cage on its root ball, despite this tree having notorious girdling roots. Let’s get you a new one. Why are some of your shrubs rotting out? We left the soaker hoses on them for years and kept them running regularly. Yes we can spray all of your plants. We can kill everything before it’s a problem.

We’re the best landscapers in town! Our services are top of the line, and we guarantee your landscape will look exactly the same as your neighbor’s.

That’s a very sardonic, hypothetical conversation between a homeowner and a landscape company. A sensible company knows you don’t know best. As a homeowner, it is wise to heed the advice of a company’s horticulturist. Cost is always a consideration for the homeowner. However, the more expensive company is not always the highest quality. Here’s why.

So, you want a Colorado blue spruce?

A responsible company won’t let you plant a blue spruce in a place with wet springs and humid summers. They will tell you why it is not a good idea, and they will suggest alternatives. For example, a concolor fir (Abies concolor) looks similar to a blue spruce. They are resistant to needle cast diseases and cytospora canker, and they can tolerate southeast Michigan’s alkaline soils. In the long run, it is much cheaper to get the right plant in the right place.

You will pay more for your blue spruce because, not only are you paying for installation, you are paying to spray fungicides year after year to avoid having a skeleton in your yard. Companies know there is a likelihood of replacing your newly planted blue spruces, so you are charged for it.

We love boxwoods and so do you

Maybe you do like the classic, formal look of hedges. And maybe you do like the texture offered by a boxwood or yew. That’s fine. This is the problem I see literally every single day: over-shearing.

An appropriate cultivar selection is the answer. Cultivars and hybrids exist which only grow to x-amount tall and x-amount wide. Simply read the tag from the nursery. If your landscape company planted the proper plants the first time, they wouldn’t be able to charge you as much as they do to “maintain” them. The right plants in the right places need very little maintenance. I will concede, a few plants can tolerate being sheared. Once in a great while is acceptable; not three times a year.

Excessive shearing stresses out a plant. In fact, certain chemicals released by the open wounds of the leaves attract insects. Wet, exposed tissue serves as a breeding ground for fungi. Some of the problems your shrubs face are directly caused by the shearing itself.

PlantAmnesty, a website dedicated to stopping bad pruning practices states:

Any pruning book will explain that one prunes to open up the center of the plant, allowing air and light penetration to make the plant healthy. Shearing, on the other hand, creates a twiggy outer shell that gets ever denser and collects more deadwood and dead leaves every year, the opposite of a healthy condition. The results create the perfect protected place for pests and diseases, akin to locking up the house so the garbage can’t be removed. After many years, this treatment can lead to disease and general bad health without actually being a disease itself. If plants have mites and blights, bugs and mildews galore, how they were pruned may be the root of the problem.

Not to mention, the plant is spending all of its energy regrowing those leaves you continually cut off. There are correct ways to prune plants, and none of them include the excessive use of motorized shears. A plant grows to reach an equilibrium with its environment. If the environment is adequate, the plant will grow. If the environment is unfavorable, the plant will decline. In other words, if it is growing, let it grow!

What’s a monoculture?

There seems to be only 15 plants which are acceptable to the landscaper. The plant selection is predictable. Certainly there are more than 15 different species of plants you can have on your property. Sure, some redundant species are okay: white pines, oaks, maples (except that damned Norway maple). I don’t want to discourage people from exploring new options, though.

Native plants offer easy beauty. They have evolved in your region for millennia and are therefore adapted to your environmental conditions. These plants often tolerate both biological and environmental stressors better than non-native plants. Expenses are saved when you don’t have to pay for disease control. You wouldn’t buy a vehicle, for example, that you know would break down and require fixing all the time.

There are dozens of other shrub options for texture, winter interest, privacy walls, etc., that you don’t have to hire a crew to shear every month. Surprisingly, some large yucca species are hardy in colder zones, which offer a different texture. Red-twig dogwoods provide colorful winter interest; there are red, green, and yellow-stemmed cultivars. Coyote willow is native to southeast Michigan. It is a thin-leafed, rhizomatous Salix species which forms beautiful yellow walls in the fall. An entire, separate article can be written on the subject of alternatives. Just know there are plenty of species to choose from no matter where you live.

Ask, and you shall receive

This request comes from homeowners and is often fulfilled by companies: “Can’t you just spray it?” Granting this request is entirely wrong. One cannot, by law and by principle, go around as a pesticide desperado. You live in that environment. Why would you want pesticides in excess? Chemicals are used as a last resort and strictly on an as needed basis.

Appropriate timing, safety precautions, and proper insect identification are all legally required before insecticides can be applied. Some of the ‘yes’-type companies will comply with all uneducated (and sometimes unsafe) requests.

Some of the appointments I have with customers address very rudimentary horticultural problems. The homeowner’s concerns are legitimate. Most problems they are having, though, can be avoided with an ounce of foresight. Issues include planting hemlock trees in full sun, or replacing a Japanese maple killed by verticillium wilt with another Japanese maple. The list goes on…

Saying ‘No’

There’s a myriad of things that can go wrong in a landscape. It is an artificial environment containing plants which evolved continents apart. Plants often don’t have the capacity to combat pathogens that they are not exposed to in their native habitats, but certain issues are impossible to predict. There is a base knowledge one should have before making these kinds of decisions. The “customer is always right” philosophy doesn’t apply in this domain. You should have some creative influence on your landscape; it’s yours, after all. Spend the time in the nursery looking for interesting plants, make a list, and run it by your landscaper. If they say ‘yes’ to all of your choices, fire them. The people you hire cannot be too timid to tell you ‘no’ sometimes.

“Right plant, right place” is the mantra among plant health care technicians. We are the people who have to clean up the messes made by your landscapers. If your landscaper did their job with longevity in mind, I probably wouldn’t have much to do.

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Drought Tolerant Plants: The Junipers

When I first developed a real interest in plants, I was in the heyday of my zine writing career. As my interest in gardening grew, writing a zine about it became inevitable. Initially I envisioned the zine as a journal of sorts – the journal of a budding horticulturist (pun intentional). Since I was new to gardening – and plants in general – the zine was meant to follow my journey as I explored this new world.

A zine needs a name though, so what would I call it? It didn’t take long for me to land on, The Juniper. I was familiar with a common disdain for the unsightly, overgrown, neglected, evergreen shrub full of spiders and cobwebs that for whatever reason was at one point planted right outside just about every house in America (a fire hazard, by the way). I was aware that many people were resorting to tearing them out, cursing as they battled the pokey, dirty, half dead things.

That was basically all I knew about junipers – they were common landscape plants that were just as commonly despised. My affection for freaks, geeks, outsiders, and rejects led me to name my zine after a shrub that everyone hated. I guess I just felt like we had something in common, and that despite being the bane of people’s existence, it deserved some recognition.

the juniper zine

And it does. Junipers are an important species in their natural habitats. In some areas they are dominant features to the point where entire plant communities are named after them. Consider the piñon-juniper woodlands of western North America – prominent steppe habitats that occur throughout high desert regions and support diverse forms of wildlife unique to this part of the world. Dan Johnson writes in the book, Steppes, “the piñon-juniper zone dominates huge expanses of the West in varying stages of  health, providing a wealth of habitats and resources to the wildlife and the people who call it home.”

Johnson goes on to describe some of these habitats:

In the Colorado Plateau this zone is dominated by Pinus edulis and Juniperus osteosperma, with J. scopulorum occupying drainages with more moisture. In the Great Basin, P. edulis is replaced by P. monophylla as the dominant piñon pine, still mixing with J. osteosperma, yet as one moves west, this juniper is increasingly replaced by J. occidentalis. Move farther north, and J. occidentalis dominates completely, with neither piñon pine making an appearance.

The genus Juniperus is in the cypress family (Cupressaceae) and includes up to 67 species, at least 13 of which are native to North America. They are long-lived plants that range from prostrate, sprawling groundcovers to expansive, bushy shrubs to tall, narrow trees. Their foliage is evergreen and can be either needle-like or scale-like. Most juniper species have needle-like foliage in their seedling and juvenile stages and then scale-like foliage at maturity. Some species, like J. communis, never develop scale-like foliage. Junipers are gymnosperms, so their reproductive structures are housed in cones. However, their cones are fleshy and so are commonly (and mistakenly) referred to as berries or fruits. Juniper cones are most often blue or gray-blue, but in some species they have a red, brown, or orange hue.

In general, junipers are quite drought tolerant, particularly those species that are adapted to hot, dry climates. Again referring to piñon-juniper steppes, Johnson writes, “in prolonged periods of drought, the piñon pines seem to suffer long before the junipers; whole hillsides of pine may go brown, leaving islands of olive-green juniper relatively unscathed.” In the book, Shrubs of the Great Basin, Hugh Mozingo attributes this drought toughness to the scale-like leaves: “Because they are smaller and so closely appressed to the twigs, these scale-like leaves are a superior adaptation to the frequently very dry conditions in piñon-juniper communities.” This herculean ability to survive on little water makes them a great addition to a dry garden.

But we may first have to get over our disdain for them. As this post on Chicago Botanic Garden’s website puts it: “Junipers have suffered from overuse and underimagination.” (This article also examines our hatred of juniper bushes). Probably a bigger problem is that, like so many other plants used in a landscape, mature height and width often isn’t taken into consideration, and rather than removing a plant when it gets too big for the site, sheers or a hedge trimmer are regularly deployed. I’m not a huge fan of the sheered look. I much prefer a more natural form to the boxes and globes that are so common in commercial and residential plantings. I’m even less of a fan of the misguided inclination to force a plant to fit in a space that it isn’t meant to be (unless you’re a bonsai artist, I guess). This treatment is what leads to exposing the ugly, brown insides of a juniper shrub – an unsightly look that only makes people hate them more.

Brown insides of juniper shrub exposed after years of forcing the plant to fit in a site that is too small for its britches.

Brown insides of juniper shrub exposed after years of forcing the plant to fit in an improper site.

There are numerous commercially available cultivars of juniper species, offering a plethora of sizes, shapes, and forms as well as various colors of foliage. For small or narrow areas, select dwarf varieties or columnar forms that won’t need to be kept in check, and in all cases let the plant express its authentic self, controlling the urge to sheer and shape it against its will.

As if their natural beauty and low water requirement wasn’t enough, junipers are also great for supporting wildlife. Birds and other animals use them for cover and for nesting sites. The fleshy cones are edible, the shredding bark is used for nesting material, and the evergreen foliage provides much needed protection during winter months. Oh and, among many other benefits that junipers offer humans, their aromatic, fleshy cones have culinary value and are used to flavor gin.

I don’t want to leave the impression that I am opposed to pruning and shaping shrubs. For aesthetic reasons, I think it should be done. However, my opinion is that unnatural shapes should be avoided. Sure, boxed hedge rows have their place in certain types of gardens, but my preference is towards more natural shapes. The following video by University of Illinois Extension provides a brief tutorial on how to achieve that.   

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Rosemary Christmas Tree

In the spirit of the holiday season, consider this fun alternative to a conventional Christmas tree. Rosemary (Rosmarinus officinalis) is an herbaceous, evergreen shrub or subshrub and is commonly found in herb gardens. Its leaves are valued for their myriad culinary and medicinal uses. Futhermore, this plant takes very kindly to pruning and shaping, which makes transforming it into a miniature Christmas tree a very simple task.

It may be too late to cultivate a “tree” for this year’s holiday season, but perhaps you’d like to try for next year. To do so, find a small rosemary plant at a local garden center or plant sale in the spring. Make a few initial pruning cuts to select a leader or leaders. After about a month or two, start giving it the shape of a Christmas tree. Floral scissors work great for making these cuts, and you don’t have to worry about where on the branches you are cutting – rosemary is very forgiving – just make sure your scissors are sharp. Wait a couple more months and then do more shaping with the pruning scissors. Do some final shaping a month or so later. At this point, you should be entering the holiday season and your rosemary Christmas tree will be ready to display. It’s that simple!

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Initial pruning: selecting the leaders

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Second pruning: giving it shape

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Third pruning: keeping in shape

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Final pruning: clean it up and present it  

One major downside to growing rosemary if you live in a cold climate is that it is only hardy to about USDA zone 7. However, if you select the right cultivar, place it in a protected location (near the south facing wall of a building perhaps), give it some mulch and maybe a blanket for the winter, you might be able to get it to survive in colder zones. Rosemary can also be difficult to overwinter indoors because the air in homes is typically dry and warm and there is little direct sunlight. If you are determined to keep one alive despite your odds, awaytogarden.com provides an excellent tutorial about overwintering rosemary both indoors and out.

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Crape Murder and Other Crimes

Here is something that will hopefully provide you with a little comic relief…and perhaps bring a little contempt as well. Recently, I was talking with a woman from Texas, and she informed me of an appalling ritual referred to, by those opposed to it, as “Crape Murder.” It’s being carried out on an ornamental tree that was brought over to the United States from Asia. The tree is commonly known as crape myrtle (Lagerstroemia spp.). It is very popular throughout the southern United States and has a reputation of being one of the most beautiful additions to a landscape due to its appealing natural shape, its propensity to flower all summer long, and its attractive bark. The “murder” aspect comes in when folks who, ignorant of proper horticulture techniques (and with a poor opinion on what might be considered “aesthetically appealing”) hack the branches of crape myrtles back at the end of the season so that all that is left of the poor things are nubby trunks. Apparently they think they are doing the tree and themselves a service, but the results of this action aren’t serving anyone – especially the trees. There are a number of passionate arguments against this heinous act found on the internet. Here is a link to one. There is also a facebook page devoted to bringing an end to Crape Murder.

This discussion reminded me of a post that I read on Garden Rant a little while back. The author was ranting against what he calls “plant janitors,” pointing out the atrocities that are carried out by these nefarious creatures on a daily basis. It turns out that the author of this rant also has a facebook page devoted to “crimes against horticulture.”

All of this is quite comforting to me, because it has helped me to realize that I am not the only one who gets squeamish when I see the hideous things that people decide to do to their plants and to their landscapes. Now that I am aware that there are plenty of other places on the internet to let off steam and rant about these issues, I can assure you that I will refrain from doing such things here. For the most part anyway…

crape murder