Mulch is a Must in Your Landscape

My previous article outlined the benefits of planting trees during the winter dormant season.  Once planted, it’s then time to implement one of the best practices that helps ensure successful establishment of recently installed trees and shrubs – mulching.

Mulching, by definition, is simply the process of adding a layer of material over the top of the soil.  Like planting at the right time, mulching does many great things for your landscape.  Mulching helps moderate temperatures; the soil stays warmer in the winter and cooler in the summer.  Mulching increases water retention; when the sun isn’t blasting directly onto the soil, it dries out much more slowly.  Mulching reduces weed pressure; most weed seeds require sunlight to germinate.  Etc. Etc.  The benefits of mulch abound.  But what material you use and how you apply mulch figure heavily into whether your mulch helps or harms the plants whose roots it lies over.

Pine bark mulch applied correctly in a landscape. Photo courtesy of Daniel Leonard.

There are two basic options when considering mulch: organic or inorganic sources.  In general, you should always select an organic mulch that is derived from local sources.  Organic mulches are mulches derived from natural materials like pine straw, leaves, tree bark, or shredded wood chips.  These mulches break down over time and benefit soil health through bettering water holding capacity, increasing soil porosity and organic matter content, and drastically expanding the soil biome (beneficial worms, fungus, and bacteria that live in the soil).   Organic mulches also allow landscapes to blend in with the natural areas surrounding homesites as they typically use materials found in local ecosystems.  For example, in the coastal south, pine forests dominate, pine straw is plentiful, and purchasing usually supports local businesses that grow, harvest, and market the straw.  So, unless you happen to live in a desert environment where rocks are natural, steer clear of rocks or other inorganic mulches.

Pinestraw mulch applied around a newly planted tree. Photo courtesy of Daniel Leonard.

As with most things, there is a Goldilocks zone for mulch.  Too little isn’t enough to keep weeds from easily poking through and soil from quickly drying.  Too much and you risk depriving plant roots from oxygen exchange with air above, trapping too much moisture and causing rot issues, or even creating a hydrophobic layer of dried mulch that repels rainfall and irrigation.  Instead, just the right amount of mulch should be applied, enough to create a 2-3” layer of helpful mulch.  With some mulches like straw, this may mean applying a 6-8” layer that will settle down to the magic 2-3” number with a good rain, interlocking the individual pieces of straw.  With others like wood chips or bark nuggets, there will be little settling, and the applied amount should be 2-3” deep.  A final tip is to always pull mulch back a little from the crowns of plants and the trunks of woody trees and shrubs to prevent potential disease issues.

So, after you install your new landscape plants this winter, remember to mulch well.  Be sure to select an organic mulch that supports local industries, enhances the soil in your landscapes, protects your plants’ roots, prevents weeds, and looks natural!  For more information about mulch or any other horticultural topic, contact your local UF/IFAS County Extension Office.  Happy Gardening!