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.

Big Trees understands that construction schedules and moving times do not always coincide with the best time to transplant trees.  Ideally trees are transplanted when they are dormant.  This is the period after the leaves drop in fall and before the spring growth begins.  However, not to worry if you missed the ideal transplant time because with 25 years of transplanting experience we have developed a method that allows for successful summer transplants. 

We are able to transplant trees in the summer with additional steps and treatments.   The aim of antitranspirant and antidesiccant treatment applications are to reduce the water loss, and stress associated with water loss, of trees during the transplant process. 

Just what are antidesiccants and antitranspirants?  The dictionary gives two different meanings for ‘desiccant’ and ‘transpire’.  Desiccation means to ‘dry or dehydrate’, where transpiration means to ‘pass through pores or membranes.’  In the horticultural world an antidesiccant would be a substance used to stop dehydration in plants and an antitranspirant would be a substance that stops the loss of water from leaves.  In the horticultural world both terms can be interchanged.  For simplicity let’s just use antitranspirant from here on out.

Here is a brief introduction on tree biology which may help you understand how antitranspirants work.  The evaporation of water from plants is called transpiration, and almost all transpiration occurs through leaf openings called stomata.  Water is literally pulled to the tops of the trees by transpiration. Transpiration aids plants in mineral and water absorption, and it is necessary for the plant process of photosynthesis, which is critical for tree growth and ultimately the well being of the plant.

Plants control the size of the leaf openings (stomata) based on external environmental conditions and internal chemical triggers.  Transpiration is at its highest when light is available, the temperature is high, the humidity is low, there is a slight breeze and adequate water is available.  If water is unavailable during high periods of transpiration the leaves of the tree wilt because water is lost through leaf openings faster than it is being absorbed. 

Big Trees applies antitranspirants as a root soak and as a foliar spray.  The foliar spray is a clear liquid coating that forms a shield over the leaf surface.  This shield works as a physical barrier that aids in the prevention of water loss from the stomata.    The foliar spray can significantly reduce plant stress associated with water loss during the transplant period. The foliar spray also provides protection against insect damage, UV degradation and windburn.

The root soak is applied as a soil drench which can then be absorbed into the tree’s root system.  It is best absorbed into the root system when the soil is already partially moist.  Through transpiration the root soak is moved from the roots through the canopy of the tree.  The root soak contains Abscisic acid (know as ABA).  ABA works as a natural chemical trigger. As ABA is moved through the tissue of the tree it deactivates transpiration by triggering the leaf stomata to close.  The plant reduces its transpiration naturally. 

Both the root soak and the foliar spray work together to make summer transplant possible.  They should be applied at least 24 hours prior to the dig.  The effects of both applications can last up to three weeks.  The root soak and the foliar spray come as concentrates which are diluted with water before they are used.  They are easy to apply, they are environmentally friendly and completely safe, and best yet they produce excellent results.

Transplants from nearly 3,500 years ago include trees used for incense.  In a scene at Deir el Bahri, men carry a myrrh tree to Egyptian ships in Punt, a land still not clearly identified. Hatshepsut sent a trading mission down the Red Sea to procure luxuries there in about 1470 B.C.

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.

Don’t go dormant with your garden in the fall. Ideally it is the time to transplant your trees. Timing is one of the important considerations when you are planning a tree transplant. It is easier to transplant trees and shrubs when they are dormant. This is the period after the leaves turn in fall and before the spring growth begins. However, not to worry if you missed the ideal time because it is possible to transplant trees during the growing season with additional steps and treatments.

Everyone is aware the many benefits of trees, and there is recognizable value in retaining large trees in the landscape through transplanting. It’s the idea that if you already own a valuable asset, by all means keep it. The value on your home increases with a mature landscape, especially with specimen trees. Typically, the cost of replacing a tree rather than transplanting that particular tree, is anywhere from two to ten times the transplant cost.

The success of transplants depends on the tree species, the health of the tree prior to the transplant, the characteristics of the new planting site, the amount of post transplant care and of course the method of transplanting itself. The size of tree that can be relocated is limited only by ability and financial resources.

With twenty years of experience Big Trees, Inc. has developed careful transplanting techniques that lead to a 98% survivability rate of small to large specimen size trees. Transplanting trees is more skill and art rather than brute force. Experienced crews use specialized tools and careful techniques to ensure that each tree is dug properly. Root balls often appear shallow but this is because the majority of a tree’s root system responsible for supplying water and nutrients lies within the first few feet of soil.

Transplant aftercare is important when determining the success of a transplant. A transplanted tree has lost significant root mass and will require additional watering and fertilizer during the first and second growing season. Adding a two to four inch layer of organic mulch is also beneficial. Mulch reduces water loss, increases water absorption, lessens temperature fluctuations and adds nutrients to the soil. Just be sure to pull the mulch layer away at least six inches from the base of the trunk. When mulch is pilled against the trunk rot can occur.

If you have questions about transplanting please contact Big Trees, Inc. Our staff of knowledgeable horticulturalists can determine the likelihood of a successful transplant.

Screening trees are becoming more and more necessary as houses are getting closer and closer together. Let’s face it, we like our privacy and fences can only provide so much. This is where trees come into play. Our saying here at Big Trees is “Big Trees Make Great Neighbors.” Whether it’s a solid row of evergreens or a strategically placed deciduous tree, this article will help you determine what options are available and what choices are best for your particular situation.

Best Pick for Small Planting Spaces:

Emerald Green Arborvitae

One of the most popular trees for screening is the emerald green arborvitae (Thuja occidentalis ‘emerald green’). The emerald green arborvitae and the pyramidalis are different varieties of the same genus and species of tree. The emerald green has become the more popular choice over the years because it maintains a nicer shape as it matures. However, the pyramidalis are still effective screening trees.

The emerald green is a dense evergreen that maintains its deep green color all year. Because of its columnar growth habit, and limited spread, the emerald green is a great selection for small planting spaces.

If planted correctly, emerald greens will form a low maintenance solid hedge. The dense and columnar growth habit of emerald greens means that they require little maintenance and no pruning. However, emeralds can easily be sheared back to limit their spread and the tops can be trimmed to create uniform heights. Emerald greens are often planted on two to three foot centers. This means that there will be two or three feet between each tree trunk. Selecting a wider spacing means that you save on cost but you will have to wait for the hedge to become solid.

Emerald greens mature to be 15-20’ tall by 3-4’ wide. They thrive in full sun and in moist but well drained soils. When planted in shady areas, emerald greens have a tendency to thin out and develop patchy brown spots. The one down side to the emerald green is that they are slow growing. On average they will grow about 6-8” annually. Attention to irrigation and proper fertilization can help promote growth.

Best Picks for larger Planting Spaces: Leyland Cypress and Excelsa Cedars

Both the leyland cypress and the excelsa cedars make excellent screening trees. They are fast growing trees that can be hedged or maintained at a smaller size if necessary. The leyland cypress can seem less than impressive initially but they get big and full fast. Once established the leyland cypress can grow 3’ per year and the excelsa cedars trail slightly at 2’ per year.

Leyland cypress mature to be 50’ tall by 20’ wide and the excelsa matures to be 40’ tall by 12’ wide. Both are often planted on five to twelve foot centers. Our Big Tree horticulturalists can help you determine the best spacing for your particular situation and your long term landscape goals.

The leyland cypress thrives in full sun whereas the excelsa cedar will thrive in full sun to shade. Other, larger evergreen tree option are; castlewellan cypress, virescens cedar, Douglas fir, western red cedar, pines and incense cedar.

Broadleaf Evergreens

Broadleaf evergreens are leafy trees that maintain their foliage year round. Our most popular types of broadleaf evergreen used for screening are the Portuguese and English laurels. Both mature to be close to 20’ tall by 15’ wide. They can grow one to two feet per year.

Deciduous Trees 

Deciduous trees, or trees that drop their leaves in fall, are often overlooked for screening purposes. We suggest them regularly here at Big Trees because they can give you coverage when you are outside in the summer and they let light into your house in the winter. Deciduous trees often are the right shape for screening, wide at the top narrow at the base unlike evergreens which are mostly cone shaped, wide at the base and narrow at the top. Deciduous trees give you coverage when you need it and where you need it and often when they are bare in the winter the branch structure alone can create a good visual block. Some deciduous trees are better screeners than others. Trees like the thundercloud plum or ornamental pears have dense branch structure and they leaf out early and they hold their leaves longer than other deciduous trees making them excellent screening trees.

We hope this helps you narrow down the search for the perfect screening tree. Please call or Email us if you have any questions. We can help you pick the best trees for your particular situation and budget.