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Ten Common Landscape Mistakes

By Skip Richter
Contributing Editor

A beautiful landscape is a source of ongoing enjoyment. In our mind’s eye, we can imagine the Eden that we will create around our homes as we shop for plants and tend our plantings. However, when gardening fever hits, we gardeners often make some hasty, ill-informed purchases and plant-care decisions that can result in less-than-hoped-for results.

In several decades as an Extension agent, I’ve witnessed many gardening mistakes that “seemed like a good idea at the time,” and (to be honest) made quite of few of my own! Here are a few of the more common ones, with the hope of helping you avoid disappointment and maximize your enjoyment and satisfaction as you build you own corner of Eden.

Planting before preparing the planting area. As the self-appointed president of the Society for the Prevention of Cruelty to Plants, I would like to propose new legislation to set up a three-day “cooling-off period” before purchasing new plants at the garden center. It works like this. As you check out at the register, the clerk asks if you have prepared the planting beds for these plants yet. If not, they set them aside while you go home and do the needed preparations before returning to pick up your plants. This law isn’t my idea — the plants ask me to advocate for it!

Start with a soil test. Mix in the recommended fertilizer prior to planting, together with some compost to improve soil structure, internal drainage and moisture-holding capacity. It is easiest and most effective to eradicate perennial weeds, whether by digging or spraying, before the desirable plants are planted. Create raised beds if drainage is at all in question. Remember this: By the time you place the plants in the ground, you are at least 75 percent of the way to success or failure!

Not considering the mature size of a shrub. When we purchase a shrub, it is deceptively small. After planting at a proper distance, they look way too small and far apart! But in time their genetics kick in and they show their true potential. If not spaced properly, roses become crowded, which increases disease problems. That tiny shrub you placed under the bay window engulfs the window, exchanging your landscape vista for a view of its leafless interior backside. Those shrubs lining the walkway crowd it so much your guests parking at the street have to join hands and get a running head start to burst through the vegetative gauntlet that once was a walkway!

When possible, choose dwarf species or more compact cultivars. While pruning can help manage size, don’t sentence yourself to years of battling against a plant’s genetics to prevent it from taking over.

Inappropriate planting location for a tree. Trees also look so tiny out there in the landscape after we plant them. It is tempting to try to squeeze them into a space they will soon outgrow. Take their mature size into account when deciding where to plant them to avoid limbs rubbing the eaves and shingles of the home, or roots lifting up the sidewalk and driveway. Modern-lot sizes are quite small, making some of our traditional tree species less than ideal options. A smaller species may be the better choice, especially if you hope to have a long-term lawn or flowerbed in the area. Also look up for power lines before planting. If there is a utility line overhead, the power company will prune your tree for you for free, but you won’t like the results!

Choosing poorly adapted species or cultivars. Just because something is for sale in a local garden center doesn’t mean it should be planted in your area. Most garden centers are conscientious about only selling adapted plants, but I cringe sometimes at what is being offered for sale in some garden centers. Plants, especially woody ornamentals, are a long-term investment. Avoid fast-growing “trash trees” that will end up being removed a few decades later, when a long-lived, well-adapted species would be in its prime.

Do some research before purchasing a shrub, shade tree, fruit plant or even annual and perennial flowers. We’ve killed a lot of peonies, forsythias, lilacs and other wonderful plants trying to get them to like it here in Texas. Crapemyrtles not resistant to powdery mildew, roses prone to mildew or black spot, fruit cultivars with the wrong chilling requirements for your region and plants not tolerant of your area’s soil type and pH, summer heat or winter cold are all a recipe for disappointment, no matter how pretty the fruit and flowers are on the plant tags, or what you saw on that gardening show filmed in New Jersey or California!

We have many awesome species and varieties for the various soils and climate conditions across the Lone Star State. Talk to knowledgeable nursery professionals, local experienced gardeners and the agents and Master Gardeners at your County Extension Office as you choose the best Texas-tough plants for your landscape.

Improper planting practices. Consider this: A tree’s roots may extend 2-1/2 times its branch spread in all directions. Grown in a pot, all those roots are wound up in that relatively tiny container. When you plant it in the soil, those roots don’t unwind, but rather keep expanding in size as the trunk expands, eventually strangling the base of the trunk, leading to poor performance or death.

When you remove a tree from the pot, cut any circling roots you find. Trust me, new roots will quickly regrow from near the cut ends, extending out into the surrounding soil. Some tree specialists advocate for washing the container soil off of the root ball to expose inner circling roots from when the tree was in a smaller container during the growing process.

Plant it so the topmost root is at or slightly above the soil line. Planting too deep can significantly set a tree back. Either dig the hole two or three times wider than the root ball or use a spading fork to slightly loosen the soil beyond the original hole area after planting. Only put soil from the site back in around the tree roots; not compost, potting mix or fertilizer.

Build a circular berm of soil extending about a foot beyond the original root ball and about 4” high around the newly planted tree. This way, you can fill the area inside the berm with water and ensure a deep soaking of the root ball when you water. Finish with a 3–4” thick mulch as wide as the berm, if not a little wider. Trees hate grass and the wider the mulch area, the better for the tree. This also keeps the mower and string trimmer away from the tender trunk tissues.

Putting plants where you want them rather than where they want to be. Plants have an opinion about where they want to grow, and they are pretty hardheaded about it. We may picture a beautiful rose loaded with blooms under that live oak, an azalea out in that drought-prone spot in the blazing sun, or a Texas mountain laurel in that low, soggy area, but that doesn’t change the plant’s genetic programming. Give them the exposure and soil moisture conditions that make them thrive and they’ll reward you with the healthy growth and the fabulous bloom show you envisioned.

Planting without a landscape plan. I love to buy new plants! Walk me through a garden center or show me a nursery catalog and I can point out dozens of things I just must have. We gardeners tend to become “plant collectors.” You know, “So many plants, so little space.” Adding plants without planning first ends up creating a “hodge-podge plant museum” rather than a design.

We can excuse our random results by calling our landscape a “cottage garden” or “eclectic,” but it really makes sense to start out with a general plan. You can learn some basics of landscape design to help you create an attractive layout of beds and gardens. These basics will help you think through how you want your landscape to look from the bay window, patio or deck area. Then choose plants that will enhance your aesthetic preferences. Remember to consider all four seasons and select some plants to extend interest beyond spring throughout the landscape, throughout the year.

Poor training and pruning practices. Training begins when you plant your landscape woody ornamental or fruit tree. The decisions you make early on will determine the structural strength, attractive form, bloom shows and fruit production for years to come. By thinking through what the end results will be years down the line, you can make training cuts the first few years with hand pruners that will avoid your having to saw off large limbs several years later. Consider this: When you pull out a saw to remove a limb, it is an admission that you made a mistake in training the plant a few years earlier.

Advice and guidance for training landscape trees properly are easy to find online, as is help with training fruit trees. Learn about how plants respond to pruning and how to make proper cuts rather than just doing what seems right at the time. If you need to hire work, remember that owning a pickup truck and a chain saw doesn’t make someone a professional arborist! Avoid the “Two Jerks on a Chain Saw” tree service that left a flyer at your door and hire a certified arborist to do the work that will determine the strength and beauty of your trees for the remainder of the trees’ life!

Watering incorrectly. While a lack of water is certainly a problem, the two most common watering mistakes are applying too little, too often, and keeping the soil too wet. Shallow, frequent wetting of the lawn or a landscape bed promotes shallow rooting, can increase foliar disease problems and results in a greater percentage of what we apply being lost to evaporation. Roots need oxygen, so keeping the soil soggy wet can kill roots and promote root-rot diseases.

The best irrigation run times and frequencies depend on factors such as soil type, temperature, plant species and sun exposure, but as a general guide give the soil a good soaking and then allow it to dry out considerably before watering again. This minimizes disease, promotes deeper root systems and gives you the most benefit from your watering dollars. When possible, use drip rather than sprinkler irrigation to minimize foliage wetting and to increase efficiency.

Misuse of weed killers. Weed killers are designed to kill plants, not necessarily just the plants you consider to be weeds. Some products work on many types of plants, while others target either grassy or broadleaf plants. Most flowers, shrubs and trees are also broadleaf plants.

If an herbicide drifts onto desirable plants that are the same type as the targeted weeds, it will damage or kill them. If you overapply an herbicide, especially prior to a rainy period, it can wash into the root zone and also damage the trees and shrubs, whose roots extend out into the lawn.

It is a mistake to think a “weed killer” is going to work on all the weeds in your lawn. Some herbicides prevent weed seeds from establishing, while others kill existing weeds. Both types can be included in fertilizers as “weed and feed” products. These too can damage desirable plants when misapplied or over-applied.

If you must use an herbicide in your lawn, choose a product based on the weed you wish to prevent or kill, and fertilize separately because the time to prevent weeds is often not the best time to apply turf fertilizer. Many of the broadleaf products can damage sensitive St. Augustine grass when temperatures are above the mid-80s, while some of the preventative products can inhibit turf rooting, which makes the grass less able to withstand drought and recover from disease, insect or foot-traffic damage.

Before purchasing and applying a product, get some assistance with weed identification and identifying the best ingredients and timing to control your lawn’s weed species. Remember that a dense turf will choke out most weed problems, so a weedy lawn is often the sign of a thin, unhealthy lawn. Focus first on proper mowing, watering and fertilizing rather than on repeated herbicide applications year after year to create an attractive lawn.

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