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What to Do if You Must Mulch

Updated: Jun 19, 2023

Last month I implored readers to "stop the mulch madness!" So if you read that article and thought, "But John, I need some mulch for my garden," I've got some tips for you.

Stop Using Wood

Roy Diblik, the owner of Northwind Perennial Farm in Wisconsin, says that plants have never evolved to grow in a pile of wood chips. The best mulch is chopped-up leaf debris. So as the snow melts and the ground dries, if you have heaps of leaves around, run them over with the lawnmower with your bag attachment and spread the shredded leaves around your plants. Partially shredding the leaves will help them decay faster.

General Mulching Rules

Garden Year 1: 1 inch of fine mulch or 2 inches of coarse mulch

Garden Year 2: 1 inch of fine or coarse mulch at the most

Garden Year 3+: You don't need any mulch. If you see spaces between your plants after three + years, you don't have enough plants.

5 Reasons Not To Over Mulch

  1. Too much mulch can prevent water from reaching into the ground: A thick layer of mulch can become very dense, shedding water away from plants rather than letting it soak into the ground, leaving your plants starved for moisture

  2. Too much mulch can lead to oxygen starvation, and roots need oxygen to live: A thick layer of mulch can slow water evaporation from wet ground. With water occupying most of the space in the soil, air content is minimal, and diffusion of oxygen is essentially blocked, eventually leading to the death of the plant or tree.

  3. Too much mulch creates excess heat as the bark starts to decompose and can kill young plants: temperatures can reach 120-140 degrees F (like composting) and kill young plants' inner bark and prevent the hardening-off period plants must go through in the fall in preparation for winter.

  4. Too much mulch piled against a plant leads to disease: fungal and bacterial diseases can spread in moist mulch, and when the mulch is placed up against plants, the organisms eventually invade the inner bark of the plant and kill it. Rule of thumb, pull mulch 5 inches away from young plants and 1 foot away from tree trunks.

  5. Too much mulch is just plain ugly: there is nothing worse than a few plants here and there in a sea of mulch!

Alternatives to Endless Mulching

Carex and Sedges: Plant these grass-like clumping plants between your other perennials.

Plant closer together: plant 1 foot on center when you first design a garden OR go back in and fill empty areas after years 2 and 3. The picture below was taken before I pulled the mulch back from the plants; it was too close to the plants, but at least they were planted 1 foot on center!

Entrance Garden Year 1 - planted 1 foot on center
Entrance Garden Year 1 - planted 1 foot on center

Now that you're all set enjoy the coming gardening season!


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