Many people ask, “What is the big deal about mulches? And why does every horticulturist at every garden center tell me to mulch my gardens and planting beds?” 

All the reasons to use mulch:  

1. The most important reason is weed control. By covering the surface of bare soil, the sun cannot shine on weed seeds that are near the surface and stimulate them to germinate and grow.   
2. The second reason is that a 2 inch layer of mulch on the soil surface helps to keep the soil moisture levels more consistent. The water will not evaporate out of the soil in between rainfall or supplemental water applications, keeping a more consistent level of water in the soil solution for the roots to draw. 
3. The third reason is that a 2 inch layer of mulch will also keep the soil temperatures from fluctuating in either direction, colder or warmer.

When to Mulch 

• Reason three above helps to explain when to mulch. In early Spring when the soil has just thawed from being in a frozen state during Winter, the temperature of the soil 4-6 inches below grade (the surface of the soil) is usually 10 degrees below the ambient air temperature. It will fluctuate when the air temperature changes from day to day AND from day time temperatures to night time temperatures. This number climbs slowly in a gradually ascending line as the season advances.    
• The bottom line is that you should wait until the garden plants start growing as the soil gradually warms up. If you mulch too soon, it could slow the awakening of the garden.

What is Mulch?

• The best mulches are made from organically derived materials like leaves that have dropped from trees, bark from harvested trees and recycled paper materials. 
• Generally, horticulturists avoid recommending using stone or gravel products to mulch areas where plant roots are growing because of the heat holding capacity of these materials. These stones do not release the heat at night keeping the soil temperatures too high for the health of the roots and hence the plants. 
• Woody trees and shrubs; Evergreen trees and shrubs; and, woody flowering shrubs (roses are flowering woody shrubs), grow better with bark or wood based mulches – shredded bark and chunk bark products 
• Herbaceous plants like perennials, annuals and vegetable grow better with non-wood based mulches like leaf mulch or leaf compost.

How to use Mulch?

• Spread it on the ground 2 inches deep leaving 4-6 inches of space away from herbaceous stems and woody trunks.      
• Cover the ground out to the “drip line” of the plant – the perpendicular line to the ground from the end of the farthest growing branch or stem.

Which Mulch is best for me?