Landscape and garden mulch in Connecticut

The Ideal Mulch:

• is readily available,
• is easy to apply and remove,
• stays in place,
• protects against temperature extremes,
• reduces soil water losses,
• supplies organic matter to the soil,
• suppresses weeds, and
• is free of noxious weeds, insects, and diseases.

What Mulch Does

Mulch helps control soil temperature, moisture, weed growth and soil structure.

In one study comparing various mulch materials with bare soil, soil moisture percentages in mulched plots were approximately twice as high, summer soil temperatures were reduced by 8 to 13 degrees, and the average amount of time required to remove weeds was reduced by two-thirds.

Bare soil can be damaged by rainfall. As the rain hits bare soil, the impact causes particles of the soil to be splattered in different directions and results in fine particles crusting the surface, causing slow water infiltration.  On a slope, this crusting effect increases the amount of water that flows off, increasing erosion. Mulch minimizes this effect and can help keep the soil in place. In marginal areas where it is hard to grow grass, such as under a large maple or beech tree with shallow roots, mulch can keep the soil in place and still be decorative.

Organic mulches improve soil structure. As these mulches decompose, organic matter is provided to the top layer of soil that prompts soil particles to aggregate. Large aggregates increase aeration and improve moisture conditions in the soil.  The opposite example can be seen with a high clay content soil where water cannot enter the soil due to the high concentration of very fine talc-like particles.  So, with mulching, the decay and larger soil structure all work together to encourage additional root development and biological activity, further enhancing soil structure.

Does a Real Super-Mulch Exist?  Not Really.  Consider the Following:

• Black plastic warms the soil in Spring.  If not covered by mulch, it also heats the soil in Summer, and can kill plants below it with this heat build-up and lack of light.  It is very effective in stopping weeds.
• Organic mulches, such as straw, shredded leaves, pine needles, wood chips and ground bark, provide insulation over the Winter and moderate soil temperature in the Summer sun.
• Black plastic prevents evaporation of water from the soil beneath, but also blocks water from getting into the soil where the plastic is applied.
• Landscape fabrics are an alternative to black plastic and used below mulch to allow water in and inhibit weeds.
• Mineral or synthetic mulches do not contribute beneficial organic matter to the soil, however some organic mulch may contribute weed seeds and diseases to a site.

Selecting the Right Mulch

Knowing there is no one perfect mulch, selecting the one you want is based on understanding the attributes of different materials. This can help you choose the best mulch for a particular location and what is being grown in the area to be mulched. The considerations are different for gardening crops vs. landscaping around the house for decorative purposes.

Typical applications for various mulch types:

• Black plastic, straw and possibly very finely ground wood mulch are commonly used in vegetable gardens or small fruit plantings.
• Wood chips, bark chunks, and pine needles are appropriate mulches for shrub beds or around trees.
• Fine mulches, such as bark granules, wood shavings, cocoa shells, and buckwheat hulls, are attractive when used in annual or perennial beds.
• Fine gravel or crushed stone mulches look most natural when used were there may be foot traffic, a different color texture is desired or in a rock garden.

Bark Mulches

Commercial bark mulches are generally the by-products of milled fir, Douglas fir, pine, redwood, and spruce logs. Nationwide, there are variations based on the source and current building activity. Three grade standards have been adopted for landscape use based on particle size:

• Bark chunks (decorative bark).
• Bark granules (soil conditioner)
• Shredded bark.

Of the three, bark chunks are the most popular.

The most desirable characteristics of bark mulches include their excellent resistance to compaction and blowing in the wind, their attractiveness, and their availability.

Wood Chips

Wood chips are derived from many different hardwood and softwood species. They are often available from municipalities or utility companies involved in pruning or clearing trees.

In general, wood chip mulches have a high carbon to nitrogen ratio. This means that in the process of decomposing, they may temporarily reduce the supply of soil nitrogen for plant uptake. You can compensate for this loss by adding nitrogen fertilizer to mulched plants.

Compared with bark mulches, wood chips tend to lose more of their decorative appearance over time, weathering to a gray or silvery gray color. Because of this, people often renew wood chip mulches each year by adding an additional 3 to 4 inches of chips. Ground wood chips are often colored to provide a consistent color and decorative accent in landscaping applications.

Hulls of Cocoa, Buckwheat and Cottonseed

As a packaged product available at some nurseries, hulls are the processing by-products of various crops and are bagged to make garden and landscape mulches. Generally, these materials are decorative and impart a delicate, richly-textured appearance. As such, they are especially useful around highly visible shrub borders, flower beds, and rose gardens.

Processed hull mulches can be more expensive than other mulches. They also are prone to blowing in strong winds and washing out after heavy rains. Cocoa hulls, which have a strong chocolate aroma, also have high potassium content and may be toxic to some plants. Cocoa hulls may also be toxic if ingested by dogs.

Straw

Straw from wheat, Timothy, oats, rye, or barley is widely available and comparatively inexpensive. Local bailed hay would also fit in this category. These materials are used as Winter mulch around trees or shrub roots and as Summer mulch in vegetable gardens and strawberry plantings.

Straw has some trade-offs that should be considered before being applied:

• If dry, it can be flammable.
• Contains seeds that may germinate in the mulched area.
• Harbors rodents.
• Lowers the soil nitrogen supply as it decomposes.
• Must be renewed annually.
• Is easily blown by wind.
• Lacks the attractiveness of other mulches.

On the other hand, it is cheap and effectively suppresses weeds and reduces soil water losses.  As Winter mulch, it protects tender roots from cold temperature injury.

Pine Needles

Pine needles have a pleasing appearance and acidify the soil around acid-loving plants. They are regionally available based on area tree populations. As an example, large bales of pine needles are available in North Carolina due to the amount of pine trees there. If not commercially available, they can be raked up from around pine plantings.

Pine needles decompose slowly, are resistant to compaction, and are easy to work with. They provide excellent protection around newly-set or tender ornamental plants. If left on year-round, pine needles should be renewed annually.

Shredded Leaves

Leaves that have been shredded with a composting mower are sometimes used as Summer mulch. If not shredded finely enough however, the leaves tend to mat together and form a barrier that blocks free water and oxygen movement into the soil.

For best results, allow leaves to partially rot before using them as mulch. They will finish decomposing in place, contributing humus, nitrogen, and other nutrients to the soil.

Crushed Stone, Gravel and Volcanic Rock

Mineral mulches offer some advantages over the organic materials. These mulches are not blown about by wind, they do not harbor weed seeds or diseases, and they do not rob the soil of nitrogen.

Mineral mulches are used in shrub beds, driveways, walkways, and in steps. Depending on the material used, they can be fine textured or coarse.

Crushed stone and gravel are appropriate mulches for rock gardens. Some mineral mulches can be colored to blend in with features of the home, patio, or landscape.

Mineral mulch particles can be knocked out of planting beds and be a hazard if hit and thrown by rotary lawnmowers.  The stone or mineral-based mulches should be underlain with a synthetic fabric or plastic mulch, so they do not migrate down into the soil below.

Limestone chips raise the pH of the soil and thus should not be used around acid-loving plants.

Black Plastic

The best features of black plastic are its abilities to prevent weeds and retain soil moisture. It is commonly used in vegetable and small fruit plantings and is often applied as a layer under wood, bark, or mineral chips.

Unfortunately, although black plastic prevents water from exiting the soil, it also prevents water from entering the soil. This may not be an issue where it is used in crop areas with alternating patches of open areas, but should be part of the consideration in wide landscape beds.

Geotextiles (or Landscape Fabrics)

For years, a hybrid product has been available that acts like black plastic without some of the negative features.  Geotextiles (or landscape fabrics) come in couple of forms. They let water enter the subsoil and some have weed preventatives in the material.

These woven and nonwoven fabrics of polypropylene or polyester are an improvement over traditional black plastic. They not only block weed growth and reduce surface evaporation, but also allow water, fertilizer, and oxygen to penetrate easily through to the soil.

Used alone as mulches, geotextiles can be degraded by the ultraviolet rays of the sun. They are used more frequently as mulch underliners, enhancing the weed-suppressing ability of the mulch while separating the mulch and soil.

Nonwoven polyester fabrics generally last longer and have greater resistance to chemical and temperature degradation than do polypropylene materials. Polyester mulches, however, are usually more expensive.

Polypropylene fabrics are manufactured by either weaving fibers together or bonding short or continuously spun fibers together. The nonwoven fabrics are bonded by needle punching, melting with chemicals or heat gluing, or molding.

With so many different geotextiles on the market, it may be difficult to choose the right fabric. Some factors to consider are:

• Ease of applying the material to the landscape.
• Ease with which water penetrates.
• Effectiveness of the material in suppressing weed growth.
• Relative cost.

Before a geotextile is applied, the area to be mulched should be cleared of all weeds.

Then, the fabric is laid on top and cut outs are made for the plants so that the fabric can be worked around the base of each plant. Then, a layer of mulch can be applied on top of the geotextile to improve appearance, reduce wear, and decrease deterioration by the sun's rays.

Although geotextiles are a great advance in mulching technology, they don't prevent all weed growth. Weeds that germinate and grow in a bark or wood chip top mulch can grow right through the fabric. Especially troublesome weeds are grass or grass-like species, such as nutsedge and Bermuda grass. To maintain a bed mulched with a geotextile effectively, destroy all weeds as soon as they are noticed.

Managing Mulches in the Landscape

Before covering an area with mulch, bring the site to its desired grade. If weeds have been a problem, consider treating the area with a pre-emergent herbicide before mulching.

Mulches applied for Winter protection should be laid down in late Fall, once the soil has cooled but before it has frozen. Summer mulches are normally applied in mid-Spring, once the soil has warmed enough for active root growth.

An organic or mineral mulch must thoroughly cover an area to a uniform depth to be most effective. Low or bare spots are prone to weed problems. Uneven mulch does not properly stop weed growth and provide good insulation of the soil.

Although there is no one mulch for all mulch needs, knowledge of the characteristics and uses of different mulches allows a gardener or landscaper to use these various materials to benefit the entire landscape.

For your mulch needs, call 203-204-3032  or contact MulchGuyBark for pick-up or delivery here in Connecticut.