Garden Mulch

An Overview of Garden Mulch

Mulch is a funny sounding word for a practice and product that provides such value. What exactly is it? Basically, it’s the term used for layers or organic material added to soil. It’s only since the 1970s that the practice of mulching began to catch on. Now it’s de rigueur for conscientious gardeners, who endlessly expound its virtues.

The major benefits of mulch are:

  • It reduces water loss from the soil.
  • Suppression of weed growth
  • Protection from soil temperature extremes.
  • Soil building and feeding, achieved by layers of organic matter than break down over time to form humus, which provides a source of nitrogen and phosphorus, as well as many trace elements.
  • It lightens clay soils and bulks up sandy soils.
  • It protects soil from wind erosion and provides an extra blanket of protection to plants in winter.

What types of mulch materials are there?

Materials range from compost, grass clippings, manure, leaves, wood chips, pine needles, straw, hay, coffee grounds, and even weeds (with no seeds!). Technically, non-organic material such as landscape fabric, gravel and rocks can provide a mulch, but avoid materials that may break down and contaminate the soil, such as black plastic, and cedar or treated wood chips.

How much mulch do you need?

A three-inch (7.5 cm) layer of mulch is usually applied. If you wanted to add a three-inch layer of organic material to a 200 square foot garden, you would need two cubic yards or material. (Two cubic yards is the amount that would fill a square bin four-feet high and four-feet wide, which happens to be the ideal holding capacity of a compost bin!).

So if you calculate the square footage of your garden beds, you will know how many full compost bins you need in order to be able to spread three inches of compost over them every years. How wimple can that be?

When do you apply mulch for maximum benefit?

Mulch garden beds every fall, immediately after the final weeding, cutback and clean up is done. It’s the last thing to do in the garden before’pu8ttin it to bed for the winter’.

In addition to increasing biological activity in the solid and feeding plants, mulch covers weed seeds so they will not germinate. Surveying tidy beds covered in a cozy layer of mulch is very satisfying.

Tip: Before covering beds with mulch, replace plant labels while you know what and where the plants are. Tomato cages work well for marking where bulbs, peonies and dhlia tubers are. Place cages over any areas you want left undisturbed.

*In hot weather, mulch acts as an insulating barrier preventing evaporation and locking moisture into the soil. The only time not to mulch is when the ground is cold or waterlogged.

Are there any problems with mulching?

Wood-based mulches, such as sawdust of wood chips, and carbon mulches such as hay, straw and leaves can temporarily tie up nitrogen as they start to decompose. Supplementing with additional nitrogen many be necessary if plants who sighs of stress from nitrogen deficiency, such as yellowing.

Some gardeners fear that damp layers of mulch provide breeding grounds for bugs and slugs. It’s true that bug populations will increase due to the decomposition of the mulch, but these are for the most part the ‘good bugs’, busy at work assisting in breakdown and not damaging your plants. Slugs can be attracted to mulch in wet spring conditions, and for this reason it’s best to wait until spring rains are over and the soil has warmed up before mulching. Usually by spring, mulch spread in fall has broken down to the point that it does not present problems.

Tip: If fungal problems occur, spread mulch out more thinly or remove it from under plants to increase air circulation. 


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