Ultimate Undersow

Living mulch shares many characteristics with other soil conservation practices (e.g., green manures, cover crops, etc.). But while most other crops are ultimately incorporated into the soil or eliminated by some other means, a living mulch is meant to stay in place for years. It’s very much the intersection of soil-improving crops and mulches, offering the usual benefits of both. However, its permanence makes it excel at fostering soil microbes and sequestering carbon above and below ground.

Living mulches may also fix nitrogen if they are leguminous. It’s especially noteworthy that clovers tend to offer exponential returns the longer they stay in the ground, making them excellent candidates for this long-term growth situation.

Living mulches are typically used in perennial situations — in orchards and vineyards, with production and landscaping bushes, with perennial herbaceous plants, and even in pathways or borders around annual planting areas. Because they’re kept in place for many years, the plants are perennials or self-seeders.

Some living mulch situations require low-growing plants so that the “target” plant (the one being mulched) is not overshadowed. In these situations, various thymes (e.g., creeping thyme), potentilla, subterranean clovers, and the white clovers are ideal. For pathways, mowable plants are required; this includes alfalfa, sweet clover, and red clover.

And in addition to the familiar green manure and erosion control plants above, living mulches can be various aromatic herbs such as tulsi, pennyroyal and Roman chamomile; self-seeding annual flowers such as cosmos and cornflower; and more traditional landscaping plants such as bunchberry, sedum and sweet woodruff. Other excellent living mulch options include the following.

FOR THE BEES: the pleasant-smelling lemon balm and the attractive heather and selfheal

FOR THE FRUIT TREES: the honey bee-friendly borage; the pretty verbena; and the drought-tolerant yarrow

FOR CHOP-AND-DROP-MULCH: the beautiful crimson clover and the phosphorus-mining, self-seeding buckwheat

FOR GENERAL COMPANION PLANTING: the prolific calendula and marigold

Make sure to go for diversity when you can. With living mulches, it’s often the more, the merrier!