Mulching is primarily managed for 5 main reasons being enhancement of soil’s surface, suppression of weeds, retention of moisture levels, management of uniform temperature levels with the root zone, and finally for erosion control.
Let’s start with the first of these reasons. Obvious as it is, mulching provides an enhancement to the soil’s surface in landscaped areas also providing a strong and uniform color and texture to the many tree, shrub, perennial and annual textures existing within a wide range of landscapes. No matter which type of mulch you use, they all will manage to enhance your garden.
Suppression of weeds is one of the most common reasons that mulching is done to the landscape. A managed layer of mulch at a depth of 3″ will go a long way in suppressing broadleaf and grassy weeds. Reducing the sun’s exposure to the soil’s surface high suppresses the germination of weeds in the garden thus minimizing weed problems.
Retention of moisture level in the soil is a great benefit to the gardens especially in the drought regions of the states. Keeping moisture levels maintained in the soil not only reduces the frequency of watering saving time and money, but also keeps plants in a more active growth state flourishing and performing their many beautiful traits.
Management of uniform temperature levels in the soil area offers a more stabile root zone area not fluctuating so much with seasonal changes in the environment especially in the early spring, summer and late fall. For many plants that are sensitive to early warm spells, mulching maintains the proper timing of their spring arrival minimizing harsh damage from late frost. Management of soil temperatures keep plants in a more stabile growth environment as well as high a huge role in moisture retention as described above.
Erosion control, whether temporary till a groundcover plant material provides full coverage, or whether used in areas of the landscape where erosion can potentially cause problems in soil movement due to heavy rains and wash outs.
Depth and mulching interval do somewhat work hand in hand, but there’s one thing to remember about mulching. Don’t try to eliminate intervals by doubling up the depth of application. Applying too deep of a mulch layer doesn’t provide practical benefits to the garden or to the pocketbook when considering the problems caused by over mulching.
The recommended application of mulching is an initial 3-4″ layer at initial new landscape bed installation or for individually mulched trees or shrubs. Follow up top dress mulch applications should be done by applying a 1.5″ – 2″ deep layer and no more. This is especially true with hardwood mulches that decompose even faster when deeper layers are applied due to the increased heat and moisture retained due to the heavier application. This speeds up decomposition. The surface of hardwood mulch discolors quite fast and has many gardener’s making frequent applications.
Here is the real problem. Mulch accumulation can be a real problem and can cause problems within many trees, shrubs, and perennials, Root systems become shallower and more sensitive to varying seasonal temperatures such as heat and cold,
So, here are the bottom line rules:
Apply initial mulch application at 3″-4″ depth
Top dress new mulch layer once to twice yearly (preferably once only)
Top dress at depths from 1.5″ – 2″
Timing of mulch applications many times vary with site and customer preferences. Being involved with many landscape maintenance accounts, Evergreen of Johnson finds timing very flexible, but do see more mulch applications made in the spring time to provide enhancement to the garden prior to spring’s full onset and to provide good moisture retention and weed suppression before summer’s heat.
Organic mulches come in a both bagged and bulk loose forms. Where hardwood mulch most commonly comes in bulk, it also can be purchased in bagged forms, usually the smaller 2 cub.ft. bag sizes due to it’s heavier weight. Pine bark and cypress mulches most commonly come bagged and are most commonly found in the 3 cubic ft. sizes other than some mass merchants who utilize the 2 cub. ft. size to portray a lower price.
Evergreen of Johnson City’s landscape and maintenance departments have found bagged forms of pine bark mulch to be preferred. Bagged mulch products allow easier management of product onsite due to being able to manually mobilize product easier both in and out of the vehicle. Even if you only have a car or small truck to mobilize mulch, bagged products make it possible where bulk mulches require an open bed pick up truck for transportation.
Weed Barrier fabrics can be a great benefit to suppress weeds in the landscape, but there are a couple of things to remember to ensure their effectiveness. If organic debris or matter becomes infiltrated or concentrated within the mulch layer on top of the weed fabric, then your weed problem is going to start developing above the weed fabric.
I have found that, with hardwood mulches high decomposition rate, weed barriers are effective only for a short term and not worth the investment. We at Evergreen of Johnson City only feel that weed barrier fabrics are only useful when applied beneath pine bark, cypress mulch, or other stone or gravel aggregates.
When applying weed control fabrics, manage smooth grading on the soil’s surface to ensure a smooth grade to the surface which will make the application of mulch easier and more efficient. Overlap seams 3″-4″ and utilize U staples or weed barrier pins to manage the weed barriers attachment to the soil’s surface.
Evergreen of Johnson City does not recommend the use of plastics beneath mulches due to the lack of moisture and air flow that is blocked by the non permeable texture of the plastic. Most professional weed barrier fabrics contain a certain level of porosity that allows water and air flow to move thru the fabric. This is of utmost important to most trees, shrubs, and perennials.