The Art of the Mulch: How to Master Spring’s Favorite Gardening Ritual

For gardeners, spring has a way of opening wallets as easily as forsythia and crocuses unfurl in bloom. After a long winter, we head to garden centers to restock, and mulch is almost always at the top of the list. According to a 2025 survey by The Garden Center Group, consumers spend more on “hard goods”—mulch, fertilizer, and pavers—in April and May than at any other time of year.

While most of us know the benefits of mulch (moisture retention and weed suppression), many apply it purely for the “look.” That uniform layer of black, brown, or red makes beds appear cleaner and blooms pop. But whether you’re mulching for horticulture or aesthetics, it’s easy to fall into bad habits.

Here are the essential dos and don’ts for mulching correctly this season.

❌ Don’t Build a “Mulch Volcano”

The “mulch volcano”—a thick mound of wood chips sloped high against a tree trunk—is a common sight, but it’s a slow death sentence for trees.

“If your tree looks like a lollipop stick going into the ground, it’s buried too deep,” says Robin Trott, extension horticulture educator at the University of Minnesota.

Covering the root flare (where the trunk transitions into roots) encourages girdling and rot. Instead, spread mulch in a flat doughnut shape. If your tree is already buried, gently remove the excess soil and mulch until the flare is exposed. For deep fixes, an arborist can use an air tool to clear the area without damaging the roots.

✅ Do Keep Last Year’s Mulch (Mostly)

Organic mulch enhances your soil as it breaks down. Unless you’ve dealt with a specific plant disease, there’s no need to haul away the old layer.

Before adding new material, fluff up the existing mulch with a rake. “You want to break up any matting,” Trott advises. “Under a fresh layer, matted mulch can become a breeding ground for fungus.” Since 85% of plant problems are fungal, a quick rake goes a long way.

✅ Do Add More Than You Think

While you don’t need 18 inches of coverage, a thin dusting won’t do the job. Aim for a 4-inch layer.

Why 4 inches? It’s the sweet spot for keeping soil cool and moist.
The Weed Threshold: Research shows that once mulch drops below 3 inches, weeds find enough light to return.
A Note on Bees: If you’re a fan of native ground-nesting pollinators, leave a few small patches of bare soil; a thick mulch layer can act as a barrier to their nests.

❌ Don’t Mulch Too Early

It’s tempting to cover bare dirt as soon as the sun hits, but mulching too early traps the winter cold in the ground. In cooler climates, wait until the soil temperature reaches 45°F to 50°F. A good rule of thumb? Wait until you see deciduous trees starting to break dormancy.

✅ Do Use Liquid Fertilizer (or Stakes)

Traditional granular fertilizers struggle to penetrate a thick layer of mulch. To feed your plants effectively:

Use a liquid fertilizer that can seep through the chips.
Use stakes: Pull back a small section of mulch and hammer slow-release fertilizer stakes into the root zone at the plant’s drip line, then cover them back up.

❌ Don’t Expect a Weed-Free Miracle

Mulch is a suppressant, not a force field. If dandelions are already established, they will grow through the wood chips.

The Fix: Manually pull weeds or apply an herbicide before you mulch.
The Fabric Debate: Most experts advise against landscape fabric. While it blocks weeds initially, it prevents mulch from decomposing into the soil and doesn’t stop seeds dropped by birds or wind from sprouting on top of the fabric.

✅ Don’t Worry About Soil Chemistry

There is a common myth that wood mulch “steals” nitrogen from the soil or drastically alters pH. While microbes do use nitrogen to break down fresh wood, the effect is temporary and surface-level. Whether you use wood chips, pine needles, or shredded leaves, the chemical changes rarely reach the deep root zone of your plants.