Aromatic Garden Mulches

Here’s another take on garden mulches. I found no studies supporting this particular practice, but gardening is about experimentation. Perhaps there could be some benefit in garden pest control.

The Art of French Vegetable Gardening cites one noted garden writer who does not plant herbs in her garden as companion plants. Lavender, thyme, rosemary and oregano grow on hillsides all around her. Instead, trimmings of these aromatics are mixed with bay leaves, nettles, cistus, myrtle and comfrey in her shredder to produce a woody mulch that she spreads between rows of vegetables.

The garden writer’s goal and mine is to have the shredded herb mulch repel insect pests in the vegetable garden.

I looked around my yard for aromatic herbs to trim. I found lavender, lots of rosemary, three sages, Mexican marigold, peppermint willow and catmint. A friend agreed to shred the pruned branches. We had a pleasant, fragrant, Covid-distanced visit in her backyard. I came home with a five gallon bucket of aromatic, shredded mulch.

Insects of some sort were nibbling on my transplanted spinach so they received the first batch of the aromatic mulch. A week later, they look good, likely benefitting from mulch of any kind. Observations will continue and the broccoli plants may be next to receive a topping of the aromatic mulch.

I’ve experimented with aromatic herbs in the garden before. Last year I layered branches of rosemary under some late season broccoli plants that were troubled by aphids. When hooded orioles were snacking on my apricots I hung branches of native sage around clusters of apricots as you can read about here. I can’t be sure if either of these measures made a difference but it made me feel I was doing something to limit the damage.

I did find a fascinating literature review article from the National Center for Biotechnology Information, a division of the National Institutes of Health. Companion Plants for Aphid Pest Management. There are at least three mechanisms by which companion plants such as lavender, rosemary, marigolds, calendulas, basil, savory and alliums may deter aphid populations. I’m willing to see if the shredded mulch of these plants can have the deterrent and repellent actions while making the host plants less attractive to aphids and other pests.

No controlled experiment is possible in my garden but my mantra continues—gardening is about experimentation.