Spring’s arrival brings with it longer days, America’s favorite past time, and every gardener’s yearning desire to add mulch to their garden beds. Early spring is one of the ideal times to add mulch to existing gardens. It acts like a blanket, insulating the ground from the last of the wintery winds, prevents weed seeds from reaching the sun they need to set root (not to mention spread) and it can turn almost any garden bed from looking like a worn down dress to a head turner.
Too Much of a Good Thing?
When adding mulch to a garden bed limit yourself to only one to three inches in depth, staying entirely away from areas where the roots connect with the ground. Mulch is definitely one of life’s pleasures where you can have too much of a good thing. While a few inches of mulch is beneficial, too much mulch can create a complete barrier stopping all moisture from evaporating and preventing oxygen from reaching the roots. In response plants will send their roots upwards to the ground’s surface searching for dry air rather than deeper into the ground where they are better able to sustain winds and find natural water resources.
More than a few inches of mulch around a tree, often referred to as a tree volcano, prevents the roots from reaching the air it needs.
Compounding matters, thick layers of mulch prevent water from easily evaporating, creating pools of water for the roots to drown in.
When smothered in mulch roots respond drastically. They twist and turn, often around the trunks of trees, searching for dryer ground and fresh air.
When roots become twisted like this, it’s next to impossible for them to relax and return to their healthy growth patterns. Much like people who use a girdle to squeeze into an outfit far too small for them. Hence the term “tree girdling”.
What Happens to Existing Mulch?
When excess mulch is harming plants, proceed immediately with an empty wheelbarrow and promptly remove the mulch volcano. Trees might still need treatments to repair their root systems, but at least further damage can be prevented.
When the right amount of mulch has been applied, it will decay with time and need to be refreshed. Organic mulches will leach nutrients as they decompose, improving overall soil quality.
Faced with a thin layer of last season’s organic mulch, gardeners know it can be valuable to incorporate any remaining mulch into the soil. Ideally nutrients are deep enough in the soil structure to directly benefit the roots.
Nonorganic mulch, such as dyed mulches, leach into the soil over time, but their benefits span from non-beneficial to downright harmful.
Colored mulch might initially seem appealing in a garden, but it pales in comparison to having live plants in a garden.
Types of Mulch
At first blush it might appear that there are as many mulch types as there are garden styles. For simplicity much can be divided into two distinct groups: organic and non-organic.
Organic mulches improve soil fertility, aeration, structure, and drainage as they decompose. These include sweet peet, cedar, wood chips, grass clippings, shredded paper, leaves and compost mixes.
Within this group mulches made from pine, technically a softwood, are more acidic so might not be ideal for all plants.
Cedar mulches can temporarily repel all insects, including beneficial insects, when the aroma is fresh. Avoid using cedar mulch if your goal is to attract butterflies.
Inorganic mulches can prevent weeds and have some ascetic appeal, but they do not improve soil fertility. Examples include: stones, rocks, and synthetic products.
When selecting inorganic mulches the coloring can play a critical role in its beneficial use. Dark mulches retain heat in the landscape, which may increase water evaporation and cause the landscape to overheat. Light colored mulches on the other hand are highly reflective, and therefore can heat up adjacent structures and result in glare. Neutral/beige tones often are the most suitable since they reduce glare, heat retention, and heat reflection problems.
Reducing the Cost of Mulch
Buying, installing and maintaining mulch can quickly become an expensive ordeal. Naturally, adding shrubs and perennials to a garden bed reduces the amount of mulch necessary with each application. Another effective way to reduce the economic burden of mulch while maintaining all of its benefits is to replace mulch with groundcover.
Vinca minor, sometimes referred to as periwinkle, thrives in partially shaded conditions, reaches 4 inches in high and becomes very low maintenance within a few years.
Elfin creeping thyme is another favorite mulch replacement. It is an evergreen, offers a lemony scent, is drought tolerant, and can tolerate foot traffic. Best of all, butterflies are attracted to it.
This combination makes elfin creeping thyme a great selection fir growing between stepping stones.
Drop down for Key Mulch Takeaways
When to Add Mulch
New plants enjoy the benefits mulch offers. Every new plant deserves a great mulch dressing.
If you’re growing in poor soil conditions organic mulch, such as sweet peet, can drastically improve your soil.
Spring and Fall are ideal times to protect your existing garden beds against Mother Nature’s harsh winter season.
Benefits of Mulch
Mulch creates a protective coating on soil, retaining heat and moisture.
Mulch prevents weed seeds from taking root.
Mulch looks great.
Downside to Mulch
Too much mulch stops plants from being able to access air. One to three inches is ideal.
Some mulches contain elements that damage soil. (i.e. dyes).
The wrong mulch can discourage butterflies from visiting your garden.
Types of Mulch
Organic mulches are more expensive, but beneficial.
Inorganic mulches (stone, rubber, dyed mulch, etc.) can cause harm in the long run.
Groundcovers, particularly native ones, reduce the need for mulch and can be low maintenance.
Additional shrubs and perennials reduce the need for mulch while enhancing landscapes.
Given the impact that mulch has on soil quality and home values, it plays a key role in gardening. If you are going to do it yourself, spend as much time comparing and contrasting your choices as you will buying and installing the mulch. If you are going to hire a professional, ensure they can answer all of these questions as well as we can.