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Boost your bounty of vegetables with a cover crop

Bell bean, vetch, pea and oat green manure mixture make a good cover crop that can be easily mowed or disked.
Bell bean, vetch, pea and oat green manure mixture make a good cover crop that can be easily mowed or disked. UC Regents

Q: Why should I plant a cover crop in my vegetable garden? — Karen, San Luis Obispo

A: Planting cover crops in your fallow vegetable beds has many benefits.

If you are not able to rotate your vegetable plantings each year, the planting of a legume-rich seed mix will add humus, revitalize your soil, and can save on fertilizer cost.

Deciding if you want to plant cover crops as annuals or perennials is important.

Annuals are best for a short growing season and need to be cut or tilled under after bloom.

If you are planting a legume-rich mix, make sure you inoculate the seeds before planting. The inoculant contains soil rhizoid bacteria in high numbers. This soil bacterium creates the nitrogen-fixating nodules on the plant roots that transfer nitrogen back into the soil.

If you have heavy soil that tends to compact or has big clots, plant rapeseed or mustard for their extensive root systems and their ability to break up the soil.

The annual cover crop has two planting seasons. When planting in fall or early winter, the cover crop needs to be cut and composted before its seeds will set, otherwise the plant will use the stored nitrogen for its own seed production.

Blooming buckwheat, phacelia, fava beans, bell beans, clovers, mustard and vetch attract many beneficial insects to your garden.

Perennials are great if you like to improve the “back forty” of your property by adding structure and avoiding erosion. If you missed the fall/winter planting of the cover crop seeds this year, try a spring planting.

You have the option, for example in a row with clover, to create open areas for your transplants or seeds. Spring cover crops will retain moisture in the soil, suppress weeds and are a great addition to your spring salad mix. Adding this kind of biodiversity improves the soil life and soil structure, adds humus, nitrogen and minerals to your soil and will increase the bounty of your vegetable crop.


Contact the University of California Cooperative Extension Master Gardeners: at 781-5939 from 1 to 5 p.m. on Monday and Thursday; at 473-7190 from 10 a.m. to noon on Wednesday in Arroyo Grande; and at 434-4105 from 9 a.m. to noon on Wednesday in Templeton. Visit the UCCE Master Gardeners Web site at http://ucanr.org/sites/mgslo / or  e-mail mgsanluisobispo@ucdavis.edu.