Multitudes of Mulch
Mulches are materials placed over the soil surface to maintain moisture and improve soil conditions. Mulching is one of the most beneficial things a homeowner can do for the health of a tree. Mulch can reduce water loss from the soil, minimize weed competition, and improve soil structure. Properly applied, mulch can give landscapes a handsome, well-groomed appearance. Mulch must be applied properly; if it is too deep or if the wrong material is used, it can actually cause significant harm to trees and other landscape plants.
Benefits of Proper Mulching
- Mulching helps maintain soil moisture. Evaporation is reduced, and the need for watering can be minimized.
- Helps control weeds. A two to four inch layer of mulch will reduce the germination and growth of weeds.
- Mulch serves as nature’s insulating blanket. Mulch keeps soils warmer in the winter and cooler in the summer.
- Mulch can give planting beds a uniform, well-cared for look.
Not Too Much!
The generally recommended mulching depth is two to four inches. Unfortunately, many landscapers are falling victim to a plague of over-mulching. A new term, “mulch volcanoes,” has emerged to describe mulch that has been piled up around the bases of trees.
Problems Associated with Improper Mulching
- Deep mulch can lead to excess moisture in root zone, which can stress the plant and cause root rot.
- Piling mulch against the trunk of stems or plants can stress stem tissues and may lead to insect and disease problems.
- Mulch piled high against the trunks of young trees may create habitats for rodents that chew the bark and can girdle trees.
- Thick blankets of fine mulch can become matted and may prevent the penetration of water and air. In addition, a thick layer of fine mulch can become like potting soil and may support weed growth.
Tree Fertilization - Trees require nutrients to live and thrive. When one or more of these nutrients are deficient in the soil, the tree will not reach its full landscape potential and will be more susceptible to disease and insect problems. They will have a shorter life than a similar, well fertilized tree.
Determining the Need for Fertilization - Trees in urban and suburban environments are often under high stress conditions due to low moisture availability, soil compaction, physical damage, and completion from turf, nearby trees, and shrubs. Fertilizer applications may reduce environmental stresses such as these. It is important to keep newly planted trees watered and pruned to keep weeds away from their bases to avoid excess stress.
When to Fertilize - Most trees experience a single flush of growth during spring followed by slower growth throughout the summer and fall. Because of this single flush of growth, it is desirable to have nutrients available to the tree as this growth is about to occur. The most beneficial time to apply fertilizer is from when the ground is workable in the spring until just before trees start growing in early May.