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What is a Shrub?

A Muddy Definition

what is a shrubShrubs are woody plants that mature to fifteen feet or less in height. If a tall shrub grows to over fifteen feet, it becomes a tree. The reason the height rule is important is related to legislation. For example, many states do not allow trees to be planted in locations that would grow to obscure outdoor advertising signs, but you can plant shrubs. If you are designing plant material on public rights-of-way, you will need to avoid planting trees near areas adjacent to billboards. Local ordinances often require replacement trees and shrubs, with a distinction between the mitigation points allowed for each. Utility companies may have easement restrictions that allow shrubs but do not allow trees to be planted under overhead power lines.

Why fifteen feet? It could be the maximum height maintenance crews can easily reach limbs for pruning, while still standing firmly on the ground. That makes sense. It could be because that height falls between two common growth limits. There are a lot of shrubs that can grow twelve to fifteen feet tall. There are a lot of small trees that mature to twenty to twenty-five feet tall. Not a lot finishes out between those two limits. Some, but not a lot. A single species could have variations in maximum height, depending on where it is grown. There is no clear green line drawn in the air, but fifteen feet is a good number of consensus.

Shrubs with many stems and no distinct central trunk are called bushes. A shrub is a plant branched from the base, without a leafy crown above a trunk. If you think about the definitions for long, you’ll get a headache. I just call them all shrubs.


crapemyrtle varieties and careCrapemyrtles are named for the delicate, crape-paper-like, ruffled flowers they carry at the tips of each new stem. They tolerate extreme heat and drought, and are used often in public streetscapes in the south. They are perfect under utility lines. Their showy blooms can last over one hundred days! How many other trees can you name that do that? As a result, they are very popular, and can be overused. Nobody complains, though!

Crapemyrtles are tree-formed by default, so you must make a special effort to let your supplier know if you want the natural, shrub form, instead. They are also sold in standards with a single trunk, so communication is very important when bidding a project. Don’t forget about the possibility of plain-old shrubby-formed Crapemyrtles. They can have a certain old-fashioned charm to them, especially in a shrub border. I doubt you will resist the tree-formed versions. Their legs are just too pretty.

Boxwood Basics

The Gold Standard of Shrubbery

boxwood basicsWhen we drew green balls in kindergarten to represent shrubbery, we drew Boxwoods. It’s as if we were born expecting the perfect foundation plant to be a Boxwood—before ever visiting a historic garden! Boxwoods were introduced to the U.S.—the Japanese Littleleaf in the South before the Civil War, and the Common Boxwood before the American Revolution. They are iconic, formal garden staples.

Think of a Boxwood as the prettiest girl in school. She has all sorts of problems, and can make life miserable, but she’s so pretty, you don’t care. She is extremely sensitive and vulnerable, and yet amazingly strong at the same time. She has a fragrance that some love and some hate, but all admit is unforgettable. There are a lot of Boxwood wanna-be’s, but everyone loves the original, authentic Buxus sempervirens. The soft green stems and tiny, refined leaves are irresistible.

Ornamental Grasses

Changing Attitudes

It has only been in the last few decades that any grasses, other than turf and Pampas Grass, were used in ornamental landscapes. Certainly, native grasses were not considered or appreciated as they are today! 

pampas grass at fast food restaurant Pampas Grass clumps grow to huge, tropical-looking tufts. It was often used as a focal point, surrounded by seating, or to flank entrances in the southeast. Pampas grass is native to South America. It fit perfectly with Victorian designs. It was exotic, dramatic plant material from a far-away place. It is also called Sawgrass, with a reputation for ripping through skin with jagged cuts if you are unfortunate enough to run your hands along the graceful blades. For this reason, it is a nightmare to maintain. The thick clumps grow to heights over ten feet tall. The clumps can get ragged, containing both new blades and the old, dried-out blades from years past.

The best method of rejuvenating a clump of Pampas Grass is to bind the entire plant with a bungee cord and use a chain saw to cut through the tough stems in late winter. Only female plants carry attractive plumes, so it is important to choose container material of Pampas Grass when it is in bloom to ensure worthwhile specimens.

I grew Pampas Grass at a former home, but never again. It is not practical for residential landscapes. Pampas Grass was typically used only on large properties with paid maintenance crews to deal with the challenging pruning requirements or by unsuspecting homeowners that learned the hard way to avoid it. 

Botanical Gardens vs. the Rest of Us

Practical Shrubbery

botanical garden secrets

I just visited the homes of two shut-ins to deliver flowers. There were similar things I noticed at each house. I had to practically climb around overgrown shrubbery to get to the door. There were weeds protruding from cracks in the pavement. Foliage obscured all the windows. There was a noticeable difference between the landscapes of the shut-ins and the other houses nearby. For shut-ins it is impractical to match the level of maintenance required to keep up a yard, without lots of help from others.

The same issues apply to us when we compare the quality of our residential landscape and the horticultural displays at a botanical garden. For us, it is impractical to match the level of maintenance required for professionally landscaped gardens. Botanical gardens not only have tons more people helping maintain their properties, their people are all trained in horticulture. What can be done to match that quality without breaking the bank? Don’t despair. Your landscape can rival those of the professionals. I’ll share a few trade secrets with you. 


planters, container plantsPlanters need to be big—really big. A common mistake designers make with planters is choosing small sizes. You’ll lose plant material in small containers.  “Self-watering” planters are a joke. Planters need people to keep the plant in them alive.

Raised planters within streetscapes need to be located beyond the overhang of vehicles. If not, they need to be less than fifteen inches tall to avoid damage from the bumpers. 

If trees are planted in narrow, raised planters, they tend to be unstable. I’ve seen elaborate urban landscaped medians trying to do this. The trees eventually had to be removed when they started leaning. It looked great for just a few months, but was certainly not worth the cost.

When designing plants in a planter, try to include things that flow over the sides of the planter. It’s pretty. Add tall, bold focal points. One way to get vertical height in the difficult environment of a planter is to use tall ornamental grasses. They can be very dramatic.

Plan on replacing the plant material in a planter often. It is not a natural situation for plant material. The reflected heat on the sides of planters dries out the root system and the reflected heat from the planter material is harsh. The soil dries out very quickly and can require supplemental waterings as often as three times a day during the hottest days of summer.

Well-maintained planters can be very effective in retail shopping areas, where pedestrians can view their beauty at eye level. They are a hassle, but worth it. They make people want to spend money. They also provide a connection for people with nature and beauty. In urban areas, it may be the only vegetation some people see during the day.


irrigation design basicsIrrigation is not an essential part of a landscape. You don’t have to irrigate a landscape. Your good plant choices and proper timing for planting will help the plants do alright without irrigation. Irrigation is for landscapes where you want a higher level of quality. Plants love having a reliable source of water. The amount of irrigation you need is dependent on what level of plant quality you are willing to accept.

Compromise is an important word for irrigation design. A perfect design provides even, head-to-head coverage. Good irrigation design, though, reduces that coverage by omitting heads in low-moisture requirement zones like mulched beds under trees and along the edges of buildings.  Check your design to see if there are ribbons of landscape that can make do with a row of heads on only one side. Narrow strips of land between a sidewalk and a curb can be planted in a drought-tolerant grass and may need no irrigation at all. On steep slopes, consider running a line of heads at the top of the hill and allow the water to run down the slope. This can provide adequate coverage all the way to the bottom. Adequate is acceptable in many circumstances. Consolidate high-moisture requiring plants and irrigate only what has high needs.

You need to design with compromises because some zones in the landscape are difficult to access or the plant material is not worth the extra cost. On public projects, irrigation may not be allowed. The budget may be limited. Irrigation systems deteriorate. Without regular maintenance, an irrigation system might last only a couple of years before leaking and damage cause it to be turned off permanently. Your

Good Pruning Requires An Aesthetic Reference for Quality

Being Raised Right

This is what the tree looked like before.

pruning mistakes

















This is what it looked like after it was pruned.

pruning mistakes

Some people might say, “There’s no accounting for taste.” I don’t agree. This obvious pruning tragedy was a result of a missing aesthetic reference for quality. If you were never taught what is beautiful, you won’t be able to recognize beauty or appreciate it enough to preserve it.

Contractors can be taught. A maintenance work plan must be specific about how work should be accomplished. It must be specific about the consequences of non-compliance, and who will be responsible for monitoring the work. Follow through with punitive fees for not following clear maintenance specifications.

High quality maintenance pruning is something that comes naturally for some people, but others need to be taught. Crews can be taught by trained supervisors. Field trips to see both good and bad examples of pruning can help. You cannot assume that everyone working on your landscape project will be sensitive to natural forms and artistic shapes. 

Free Plants Every Spring

A New Year with New Beginnings

free plants every springWe’ve been having a warm spell this February, and I am encouraged by the new sprouts emerging from the garden cloche cuttings I stuck in the ground last fall. I buried some stems of my favorite shrubs as deeply as possible into moist soil and covered them with large upside-down jars for the winter. To hedge my bets, I surrounded the glass jars with bubble wrap to keep the stems extra warm and toasty. Then I pulled pine straw around the bottom to keep out cold winds. When the weather warms in the spring, I pull off the jars and, voila! New plants.

free plants every springIt’s easy to build a collection of garden cloche jars. The traditional bell jars are quite expensive, but I visit thrift stores and yards sales for fifty-cent versions. Old floral containers work just fine. The handy handle topper is missing, but I can manage without it. The bigger the jars, the better.

The jars act like tiny greenhouses, holding in moisture and sunlight and warmth. Some shrub species accept this propagation method very willingly—Hydrangeas and Roses, especially. Can you have too many Hydrangeas and Roses? I don’t think so!

Amazing Shrub for Heavy Shade

Aucuba is Not Perfect, but Nobody’s Perfect

shrub for heavy shade, shade plant, shade plantsAucuba can be grown from hardiness Zones 7a to 9B. The people who live in those zones, south of the Mason-Dixon line and along the coastal perimeter of the U.S., either love it or hate it. I’ve seen it sold as a houseplant, probably because of its glossy, leathery, colorful leaves. I love it.

I’ve never noticed the flowers, and the large red fruits are only on female plants, rarely available in bread-and-butter nurseries. Most cultivars grow about four feet tall. The red berries clash with the variegated leaves, but they look striking on the all-green cultivars. The leaves are amazing. The greens are deep and dark and the variegated varieties have screaming blobs of chartreuse and yellow.

There are a few reasons people hate it. A lot of southerners remember their mothers or grandmothers using ‘Gold Dust’ in flower arrangements, rooting the ugly, thick stems in water on a sunny windowsill, and giving it away to friends. It was very popular in the sixties, but people are tired of it now. I’m not. Shrubs go in and out of fashion, and this one has not seen the “old is new again” stage in the nursery industry. Maybe five years from now.

When it gets diseased, it looks like something out of a horror flick. Stems and entire branches go completely black—black, mind you—if they contract one of the rots that attack it in poorly drained, nematode-infested soil. Other manifestations of their problems include necrosis, fungal growth, wilting, and necrotic spotting. Just the names sound disgusting!

If you plant it slightly above grade in good soil, keep mulch away from the roots, and cut out problem branches back to healthy tissue with clean clippers, the problems go away. Those fixes are quick and easy and don’t involve chemicals. Anything that doesn’t involve regular spraying is okay by me.