Tree Care Information

Getting the most from mulching, Do you mulch too much?

By Cindy Ratcliff

As published in Total Landscape Care, September 2009

Compared with the rest of the landscape, trees are about as low-maintenance as you can get, which makes them easy to overlook. Sure, you remember to water and fertilize them with the rest of the lawn, but they really need more than that to thrive. A regular maintenance program will add vigor and help prevent future problems.

Done properly, applying mulch around landscape ornamentals can be one of the best things you do for them. Mulching mistakes, by contrast, can stress and even kill plants. So it’s critical to familiarize yourself with mulching basics, as well as what kind of soil you’re working with.

The cover up
Overmulching is the most common mulching mistake perpetuated by a “monkey-see, monkey-do” mentality. In short, we’ve seen so many examples of mulch piled up high on tree trunks that we associate it with the correct way to mulch. This could not be further from the truth.

In fact, this is such a common problem that the International Society of Arboriculture has come up with a term to describe this improper method of mulching: mulch volcanoes. Its campaign against this technique implores landscapers to “mulch wide - not deep.” This epidemic of incorrect mulching has elevated to code-red status, becoming one of the leading causes of death of trees and shrubs.
Mulching too deep or too close to trees and plants can lead to plant injury and death in a number of ways:

Root suffocation. Roots need to breathe. Without acceptable levels of oxygen, roots begin to decline and will eventually die.

Dehydration. If you pile on the mulch too thick, you prohibit the penetration of water and dehydrate roots. In the case where water actually does make it through the mulch and to the soil, you then risk preventing natural evaporation, which will result in perpetually soggy soil and will eventually lead to root rot.

Fungus. Piling mulch against a tree trunk is an open invitation for fungi. The moist conditions provide the perfect environment for their growth and reproduction. Once the tree bark begins to decay, the fungi can easily enter the tree.

Insects. Research suggests some insects can instinctively detect a stressed tree or plant and will attack it preferentially. So not only will your ornamentals decline from the mulch, they will be less able to fend off insect pests.

Vertebrate pests. Thick mulch volcanoes provide a nice habitat for rodents who will feast on the inner bark of trees and cause girdling. The more extensive the chewing, the less likely you’ll be able to save the tree.

Excessive heat. You know that heat associated with composting? If your mulch is thick enough, that same process will occur. In fact, temperatures can reach 120 to 140 degrees Fahrenheit as decay occurs in the thick piles.

Unfortunately, you often won’t know if mulch is killing plants until it’s too late - sometimes the symptoms don’t show up for three to five years. You’ll probably first notice an overall decline of plant vigor and rate of growth, according to the Virginia Nursery & Landscaping Association. Symptoms can include:

• Off-color leaves (pale or marbled)
• Abnormally small leaves
• Poor twig growth
• Die-back of older branches
• Rotting, peeling trunk bark under the mulch

Mulching done right
To get the proper mix of mulch around trees and in landscape bedding, it’s imperative you consider the moisture needs of the plants, the type of soil you’re working with and the drainage characteristics. You’ll need to know these things before you select a mulch and determine the appropriate depth of the mulch.

For well-drained sites, you will typically apply a layer of mulch 2 to 4 inches deep. For soils that don’t drain well, you’ll want to keep mulch to no more than 2 inches deep. And for soils that perpetually retain water, you may have to forego mulch altogether, despite its benefits.

As you apply the mulch, remember to keep it away from tree trunks and other plants. For younger trees, your guideline should be no closer than 3 inches. For more mature trees, you’ll want to keep mulch even farther away, at a minimum distance of 8 inches. In ideal situations, you should extend the mulched area all the way to the tree’s dripline. This isn’t always possible as aesthetics often dictate a smaller mulched area, but it’s best for the health of the tree.

When selecting a type of mulch, you’ll choose from mulches in two categories. Inorganic mulches include stone, lava rock, pulverized rubber, geotextile fabrics and other materials that don’t easily decompose. Organic mulches, on the other hand, will decompose more readily and include wood chips, pine needles, leaves, cocoa hulls, softwood and hardwood bark, etc.

The benefit of inorganic mulches is that they don’t often need to be replaced; however, they do nothing to improve the soil structure, either. Organic mulches provide nutrients and improve soil quality and fertility.

The merits of mulching
In addition to making a landscape look more manicured, mulch applied correctly offers many benefits to plants. It works to improve soil conditions and helps soil maintain moisture by decreasing water loss. It also keeps weeds at bay and minimizes their competition for water and nutrients. It provides insulation for soil, keeping it warmer in the winter and cooler in the summer. It protects tree trunks and plants from string trimmer and mower damage, and it reduces soil compaction by diverting foot and vehicle traffic.

By: Valerie Easton

Gardeners struggle with views. It’s not that we don’t appreciate a panorama of water and mountains as much as the next homeowner, but we want our trees as well.

We hate it when our prized plants get lost in a big view. No one pauses to admire a magnolia or Japanese maple, let alone a clematis or tulip, no matter how gorgeous, when the Space Needle or Mount Rainier looms in the background. How can gardeners compete with a snow-topped volcano, a working harbor or the lights of the big city?

Competition, it turns out, is a losing game. Pursued to an extreme, you end up with a Disneyland cartoon of a garden. Yet for those who love plants, it’s discouraging to keep them pruned back and down so you don’t intrude on the vista.

“If people would just relax on trees a bit, they’ll get so much pleasure from both the trees and the wildlife they attract — and their views will be more dramatic and dynamic,” says landscape architect Charles Anderson. He suggests layering evergreen and deciduous trees for permanency, seasonality and peek-a-boo views. Trees lend shelter and shade, he says, bringing birds such as banded pigeons that need high perches. He suggests you pick your view, using trees to selectively screen out unwanted sights from the neighbors.

For a west-facing modern house high atop Queen Anne Hill, Anderson planted big leaf maples and madrones in front of the smashing view. Owner Phil Vogelzang says, “It’s bankrupt to get rid of the trees. They cut down on glare and give us shade, privacy and a close-up view of wildlife.” But do they block his view? “Trees can be sculpted,” he says.

Gardens make you feel safe and grounded, so you never have that queasy sense of standing on a precipice, according to designer Richard Hartlage of AHBL landscape design group. Like any garden, those with views must first relate in scale and style to the architecture of the house. This means that on a large property, conifers or elms might be used to frame the view. On a smaller urban or suburban lot, more modestly sized stewartias or dogwoods are an ideal foreground.

“If you can see a view from everywhere, it loses its impact,” says Hartlage. “So I make a judgment call — what am I going to highlight?” He closes in pieces of a garden for intimacy, while leading the eye toward the most magnificent views. His design for a Tacoma garden screens out the view from the street so you don’t see the water at first, while the main axis of the garden emphasizes the view out toward Puget Sound. “You use the garden to create progressive layers of foreground and mid-ground; otherwise, the view is just like a painting on the wall,” says Hartlage.

Landscape architect Bruce Hinckley, who designed the garden for Jim Dow’s home on page 42, says hectic city views can be fatiguing. He chose a limited, austere plant palette so it wouldn’t compete with Dow’s huge view of the city and Elliott Bay. Hinckley craned in a forest of mature black pines to modulate depth of field, meaning that the eye will focus on different depths and distances on its way to taking in the Space Needle and passing ships. “Trees bring the sky down so you can appreciate clouds and the changes in weather,” Hinckley says.

Trees also provide some measure of solar control and privacy. Finding just the right amount of shade and shelter on an exposed site can be a balancing act. “Remember, if you can see, you can also be seen,” says Hinckley. “And who wants to keep their blinds down?”

Too often, with a big panoramic view, people cease to really see it. By using trees as framing and foreground, Hinckley assures, “You may see less, but you’ll enjoy it more.”

Valerie Easton is a Seattle freelance writer and author of “A Pattern Garden.”

Proper watering practices are vital to the survival of a newly planted tree. The most common cause of decline in newly planted trees is improper irrigation.Improper irrigation can be either too much water or too little water, and the symptoms of stress from both can be indistinguishable.Proper irrigation requires a little investigation, continued monitoring and adjustments when necessary.

Irrigation amount and frequency are dependent on:

• Air Temperature
• Soil Texture
• Soil Structure
• Tree Species
• Season

With so many factors it is difficult to give an irrigation standard that is appropriate for all trees and landscapes.Generally, no irrigation is needed when trees are dormant.The period of dormancy for deciduous trees is easy to determine because they lose their leaves.Evergreens go dormant also.Use deciduous trees as indicators for the dormancy period for both types of trees.Irrigation should begin when deciduous trees start to bud up or leaf out in early spring.The most amount of water will be required mid to late summer when soil moisture has been reduced and air temperatures are at their highest.In mid to late fall the irrigation schedule can be tapered off back to a watering schedule that was used in early spring.Once fall leaf drop occurs discontinue watering until the next growing season.

Big Trees, Inc recommends that trees be irrigated with automated drip irrigation.This type of system can be as simple as a soaker hose attached to a battery operated watering timer.Drip irrigation uses the least amount of water with the highest efficiency.It evenly distributes water directly over the rootball of newly installed trees and it provides consistent moisture levels.

So how do you know if you have achieved the right irrigation frequency and timing?One simple method that gives good results requires some investigation:

• Use a trowel to dig down at the root zone approximately 4-6”.Pick up a small handful of soil and squeeze it tightly in the palm of your hand.If the soil has formed slightly to the shape of your palm after you have opened your fist, the soil moisture is ideal.If the soil easily crumbles and falls apart the moisture level is too low, and if you are able to squeeze water from the soil when it is in your fist the soil is too wet.All water should be absorbed within 6 hours, and no puddling should occur in the root zone.

Trees absorb both oxygen and water from the soil.Overly saturated soils have little available oxygen and soils that are too dry hold any moisture so tightly that it is unavailable to trees.It is a fine balance that requires continued monitoring and adjustments.

If you have any questions regarding the irrigation of your newly planted trees from Big Trees, Inc. please do not hesitate to contact us.