A mulch, is any kind of material applied to the soil surface for protection or aesthetic improvement of the area covered. The mulch material may be organic, such as bark or straw, or inert, such as stones or weed matting.
- Conserve soil moisture by reducing the evaporation of water from the soil.
- Maintains more uniform soil temperatures by insulating the soil, keeping it warm during cool spells and cool during the warm months of the year.
- Reduces weed problems when the mulch material is weed- free and is applied deeply enough to prevent weed seed germination or to smother existing small weeds. Proper use of mulches considerably reduces time and labor needed to weed gardens.
- Adds to the beauty of the landscape by providing a uniformly colored ground cover that may add an interesting texture to an otherwise drab surface.
- Prevents plants and fruit from becoming mud splashed and so reduces losses from soil-borne diseases.
When to Apply Mulch
Apply an organic mulch on most established ornamental plants in mid-spring when the soil has warmed sufficiently for active root growth. If applied before this time, the
mulch will keep the ground cool and root growth may be retarded. Apply an organic mulch around newly set ornamental plants after they are put into place and thoroughly watered.
How Deep to Apply Organic Mulches
For best results, apply mulch at least 50 – 100 mm deep over the whole area anytime during spring, summer or early autumn but avoid covering the crowns of very low-growing ornamental plants. Tender ornamentals that need winter protection may require an additional 30 – 50 mm of mulch around the crowns or bases of the plants during the winter. In the spring, this added mulch should be fanned out or away from the stems or crowns of the plants before more material is added for a summer mulch.
Fertilising Raw Organic Mulches
Mulching with many raw uncomposted organic materials--including wood chips, sawdust, straw or shredded bark--means you must apply extra fertiliser
around the plants to reduce the chance of nitrogen deficiency or starvation in your plants. Apply 2.5 kg of ammonium nitrate or ammonium sulfate for each cubic meter of mulch
material used on the bed, or 1 kg per 10 square meters of a complete fertilizer such as 5-10-5, 12-12-12 or similar analysis. This fertilizer should be applied before the mulch is placed on the soil, or in early spring before more material is added to plants already mulched. if the lower foliage yellows and the plants lack vigor during early summer, apply additional fertilizer.
Do Not Over mulch
The roots of plants need a constant supply of oxygen at all times. Over mulching kills the roots of shallow-rooted plants by suffocation.>
Symptoms of too much mulch include chlorotic (yellowing) foliage (symptoms often resemble iron deficiency), abnormally small leaves, poor growth and dieback of older branches.
Disease organisms that are active under conditions of low oxygen and excessive moisture can become active and attack the roots. Sometimes the old root system will be rotted as the plant tries to send out new roots into the mulch layer. Excessive amounts of mulch applied around tree trunks can lead to cankers on susceptible species.
Avoid deep mulch contacting the stem or crown of the plant. Excessive amounts of mulch resting directly against the stem can lead to diseases such as crown rot and stem canker.
contributed to by – Michigan state University