MULCH INSTALLATION

The Big Benefits of mulch

Mulch offers several benefits, including weed suppression, moisture retention, temperature moderation and improved aesthetics. Mulch is often overused and actually is not a landscape element but a soil amendment that replaces organic matter and adds nutrients to the garden. Organic matter needs to be replenished because it continuously breaks down and your garden will reward you when you use the right mulch and install it properly. 

Timing 

Springtime is often correlated with time to mulch, but just because the shopping plaza and your neighbor are mulching, doesn’t mean your beds are ready yet for a fresh layer of mulch. Ideally, mulch is installed when the existing mulch has become mostly depleted. Mulching too soon and too often leads to excessive mulch which can result in plant decline. 

Aged mulch that has smaller particles and appears more like compost will break down more quickly and may need to be replenished each season, while chunkier wood products may take a year or longer to break down.  

Healthy soil

Most soil is healthiest when it contains at least 5% organic matter, though annual and perennial beds require more. Organic matter reduces soil compaction, which improves air and water flow. Certain mulches are rich in nutrients that benefit the plants. Organic matter needs to be replenished periodically because it decomposes. In nature, this process occurs naturally when plant debris is recycled through the decomposition process. That process takes time – time we don’t have in our gardens. In our urban landscapes and gardens, it is necessary to remove leaves, branches and plant debris from our landscapes because they are unsightly, can be good hiding places for pests, and may smother or damage plants. By removing the leaves and debris and composting them off-site, we continue the cycle when we return the compost, leaf humus and other products to our landscapes. By replenishing organic matter into our beds with materials that have begun to decompose, we speed the cycle and provide many benefits to our urban landscapes. 

Applications

Soil amendments may be applied and incorporated into the landscape by top-dressing, forking in, or rototilling.

Top dressing – This is the most common method. Mulch is used to fill in areas of the landscape that may not be fully planted, mitigating weeds and aiding in moisture retention. Shredded hardwood bark mulches are great for this, but leaf compost and other composted material can also be used.

Forking in – Organic matter is gently worked into the soil with a pitchfork. This method is best for adding modest amounts of material that need to be quickly incorporated into the soil.

Rototilling – This method is used for new or empty beds that need a fresh supply of organic material for new plantings where there is little risk of damaging surrounding plants. 

Delicate balance

Generally, soil amendments should be added whenever the landscape has become depleted. For hardwood or bark mulch, no more than 1.5” to 2” of mulch should be applied at a time, keeping total accumulation at 2” or less. Excessive mulch can trap moisture in the soil during heavy wet periods leading to root rot; and it can prevent moisture from getting to the roots during drier periods.