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MMWD Blog: Think Blue Marin

Welcome to our blog! Written by staff at MMWD, “Think Blue Marin” explores all things water in south and central Marin—water supplies, conservation, new projects, watershed management, and more.

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Aug 31

Light

Posted on August 31, 2018 at 10:29 AM by Ann Vallee

by Charlene Burgi

Mulch has been discussed frequently in this blog. It’s a topic worth revisiting considering the benefits it provides—one being that it blocks light, preventing seed germination and thereby controlling weeds.

sunflowersBut there’s another angle to the story. Today as I drove across the cattle grate leaving the ranch here in Lassen, I noticed a field of yellow wild sunflowers growing around the old barn. They were not planted nor watered. Oddly, it is only where my friend had mowed the tall wild grasses away from the road a few months ago with the intent of making things fire safe that these posies nodded their bright cheery heads as I drove by.

The rest of the adjoining unmown field lay barren of flowers—only the tall wild grasses remained. My attention focused on the surrounding elements: short mown green grasses and lots of sunlight. The seeds laying fallow had the perfect environment for growth.

The water was still seeping from the winter mountain ranges; that field is subject to natural drainage that keeps it damp long into summer. However, the damp ground alone was not enough to spur the growth of the sunflowers in the tall grassy fields beyond the mow line. The tall grasses functioned similar to mulch, shading the seeds and suppressing germination. On the other hand, sunlight was able to get into the shorter grasses to create the display of petals of sunshine. The mulch factor did not exist in the mown zone. 

How could I not deduce the correlation between mulching and non-mulching with the proof set forth before my eyes? Luckily, the seeds that germinated were a pleasure to behold and not a field of thistles (which brings up another whole topic for a later blog).

My mind played with this juxtaposition. We’re used to thinking of mulch as a benefit. But here, the absence of mulch allowed the sunlight to do its job, which caused me to stop and stare at the splendid color. Can we, as gardeners, decide what areas we want to leave open? After all, our native mason bees need open soil for habitat, and butterflies thrive on the slurry of a moist muddy environment. Vegetable gardens also require open soil for seed germination.

I also thought of the weed seeds that mulch suppresses and how it keeps the roots of plants cool in the summer and warm in the winter months. Aesthetically, mulch covers drip tubing in the garden and provides a tidy finish to flower beds. It holds in moisture to reduce irrigation needs and adds nutrients to the soil as it breaks down, thereby nourishing our plants. 

Given the laundry list of mulch benefits, I’ve long concluded that mulch is of great value to all gardens. But it is also a benefit to save sections in our gardens without mulch to encourage light for wildflower and veggies seeds as well as support mason bees and butterflies. The question is how much of an area do we give? What a wonderful choice for every individual gardener to decide!

Have a restful Labor Day weekend. You earned it!

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