MULCH so Many Benefits and so Many Choices

Why Mulch?   

  • Mulch adds nutrients to the soil and increases soil microbes. Soil microbes are responsible for breaking down organic matter and organic fertilizers and converting them into nutrients that the plants can easily absorb.
  • Mulch holds in moisture, reducing watering requirements and keeps the soil at a more consistent moisture level.
  • Mulch suppresses weeds by shutting out light and any weed seeds that do germinate are usually very easy to pull up.
  • Mulch reduces soil compaction.
  • Mulch improves a soils structure.
  • Mulch reduces splash up from rain and overhead watering. This helps to prevent fungal diseases in the garden.
  • Mulch keeps soil cooler in summer and shades roots.
  • Mulch insulates the soil in the winter and helps to reduce soil temperature fluctuations that can create winter kill.
  • Mulch can greatly enhance the appearance of your beds and borders.

When to Mulch?  

The best time to mulch is after you have finished planting in May. By this time your soil should be sufficiently warmed. Mulching to early, before your soil temperature has a chance to warm, will slow down root and plant growth. Major soil disturbances after mulching may require additional mulch.

  • Cocoa Bean Hulls are known for their chocolaty aroma which can last for a couple of weeks. They are best used in a sunny location as they tend to mold in shadier, moister locations. This mold is not harmful to the soil or the plant but it is not the most visually appealing. Cocoa Bean Hulls tend to break down very quickly and need to be replaced yearly. They also add potassium to the soil . Potassium is a necessary mineral; it helps to regulate a plants metabolism and contributes to early growth, stem strength, hardiness, vigor, good flower colour and disease resistance. It is also essential for the proper development of root crops. However care must be taken as to much potassium will tie up magnesium (making it unavailable to the plants) another necessary mineral. Apply only a thin layer of this mulch approximately 1” thick.
  • Compost and Composted Manures provide nutrients to the soil, increases soil microbial activity, improves soil structure and helps to prevent weed seeds from germinating. It is highly attractive and one of the most natural looking mulches.
  • Decorative Shredded wood mulches: is costly but attractive. Available in a variety of textures and colors. Two cons of wood mulches are: the deep brown, red and black mulches are all dyed and have a tendency to fade quickly and they can form a crust that prevents water from filtering into the soil (to help prevent this rake them occasionally). Wood mulch need to be topped up yearly. The finer the shred the faster they break down.
  • Pine Bark Nuggets are attractive and decompose slowly compared to wood mulches. They are costly. Their drawback is that they tend to draw moisture out of the soil rather than hold it in.
  • Ground Covers (living mulch) periwinkle, lamium, thyme, pachysandra, viola, etc. While they do help to reduce weeds by choking them out they can be hard to weed out.
  • Decorative stone is best used with landscape cloth underneath it. It is an attractive long lasting mulch. Suitable for unplanted areas and areas with just a few trees and shrubs. A few cons include: it is very difficult to weed out especially tree seedlings and grass, plant maintenance and fertilizing can be difficult, and it is very difficult to remove.
  • Grass clippings are free and readily available to most home owners. They are high in nitrogen.
  • Straw – the ultimate temporary winter mulch for tender perennials and lower shrubs
  • Shredded tree and shrub materials extremely cheap (sometimes free!), highly effective as organic material but needs frequent replenishing, can be overly dirty (e.g. weed seeds, insects, disease)
  • Pine Needles are readily available, usually free, best for woodland gardens.
  • Leaves are plentiful and free. If your trees do not provide enough leaves for your needs neighbours will usually be more than willing to let you have some of theirs. Allow the leaves to dry then chop them up by running over them with a lawnmower, weed whackers work well as do shredders. Once shredded apply a layer to your beds and borders in late fall. Cons include: they can be a source of weed seeds and trees seedling and also harbour overwintering insects.

Landscape Cloth

Landscape fabric is a specially designed, permeable fabric, most often made of woven polypropylene. It may be laid underneath your mulch to further block sunlight from reaching weed seeds and to keep air borne seeds from making contact with the soil. There are both benefits and draw backs to using landscape cloth so consider its use carefully.

  • Pros to using Landscape Cloth:
    • Are excellent for under decks, gravel paths, stone mulches and paving stones
    • They are suitable for short term weed suppression in vegetable beds.
    • Good barrier against invasive roots and digging/ tunneling pests
    • Makes a good pot liner.
    • Good for erosion control.
  • Cons to using Landscape Cloth
    • Weeds that sprout in the mulch and penetrate the cloth are difficult to weed out and may tear the cloth when they are pulled.  
    • The mulch will be prevented from enriching the soil and building up the soil microbial population, (mulch must have contact with the soil to perform this function).
    • The cloth prevents the incorporation of organic granular fertilizer and soil amendments. These fertilizers need to be in contact with the soil in order for soil microbes to break to them down and convert them into a form the plants can take up.
    • Interferes with planting and trans-planting (the cloth needs to be cut).
    • Prevents natural plant growth. The cloth must be continuously cut wider to accommodate new growth. Failure to do so may create girdling and even eventual death of the plant.
    • Contrary to what some manufactures claim they tend not to be a not long term solution.  Between tears, cuts and natural degrading the fabric life can be relatively short.

There are so many benefits to mulching including improving curb appeal and saving you hours of work in the garden. With so many types of mulch to choice from there is one to suit almost any need in the landscape.

Updated on May 16, 2022

Photo credits: all photos have been taken by the author.

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