Cover Crops in the Home Garden

As gardeners, we have the seemingly endless task of improving and maintaining the health of our soil.  Composting is a commonly used strategy.  But this is a labor-intensive task.  The novice gardener will quickly realize it is difficult to make enough compost for even a small garden.    And anyone with physical limitations may find building and turning a compost pile difficult.

An alternative practice often overlooked in home gardens is growing cover crops.  This simple and inexpensive practice can work wonders for the health of your soil.

Benefits of Adding Cover Crops

There are many reasons for growing cover crops.  Cover crops can:

  • Capture nutrients that might leach away during the winter.
  • Prevent erosion of the soil during rainstorms.
  • Improve the structure of the soil.
  • Bring up nutrients from deep in the soil.
  • Reduce compaction of the soil .
  • Provide pathways for the roots of future crops.
  • Leguminous plants can fix nitrogen in the soil, reducing the need for expensive fertilizers.
  • Suppress the growth of weeds.
  • Provide habitat for beneficial insects.
  • Attract pollinators when in bloom.
  • Most can be grown in the winter when the garden would otherwise be unproductive.
  • Improve the ability of the soil to retain nutrients.

Cover crops are usually divided into legumes and non-legumes.  The legumes fix nitrogen in the soil.  The non-legumes add biomass and/or break up compacted soil.  Cover crop mixes combining the two are often used.

In my own garden, I have maintained fertility with a combination of cover crops and a modest amount of compost.  Soil tests have consistently shown high to very high levels of all nutrients tested and a high percentage of organic matter.  In addition, my normally heavy clay soil now has a loose and crumbly texture.

How to Add Cover Crops to Your Garden

To grow a cover crop, simply clear the residues of the previous crop and broadcast the cover crop seed evenly.  Lightly rake in the seed for good soil contact.  For maximum benefit, grow the cover crop until flowering and then terminate it.  Turn it under and chop it into the soil, or use a rototiller.  For easier processing, I like to cut off the aboveground growth with a weed trimmer and add it to the compost pile.  Or just mow the cover crop and leave the residue on the surface as a mulch.   Don’t let the cover crop go to seed, or it can become a weed in a later crop.

Cover crop seeds can be pricey if purchased from a seed catalog.  Find a feed and seed store that supplies farmers.  My local store carries a good variety of cover crop seeds.   I can buy enough seeds for about five dollars to plant my entire garden.  Make your own combinations of legumes and non-legumes.  My favorite combination is cereal rye, hairy vetch, and Austrian winter pea.  This provides biomass, nitrogen-fixing, and edible pea shoots in the winter.

Most cover crops are grown during the winter when the garden would normally be out of production.  They should be carefully planned so that they don’t delay the planting of food crops in the spring.  It can take three or four weeks after terminating a cover crop before it decomposes and other crops can be planted.  Also, chopping in a cover crop can be strenuous and may not be advisable for someone with physical limitations and no access to a rototiller.  You may plant cover crops that will winter kill, such as oats or fodder radishes, in areas that will be planted early in the spring.

Selecting Cover Crops for Your Needs

The following are the characteristics of some cover crops that are commonly grown.

  • Cereal Rye – This and other grasses (wheat, oats, barley) add biomass to the soil and reach their roots deep to bring up nutrients.  Excellent for improving soil structure.  When the roots decompose, they leave pathways for other crops to extend their roots.  It is sown in the fall and incorporated into the soil in the spring.
  • Hairy Vetch – One of the best nitrogen fixers. It can fix 2 pounds of nitrogen in 1000 square feet.  Sown in the fall and overwintered for spring harvest.

    Hairy Vetch Cover Crop
    Hairy Vetch
  • Oats – Adds biomass and suppresses weeds. Sown in the fall, it may winter kill, making it easier and faster to incorporate in the spring.
  • Austrian Winter Pea – Fixes nitrogen. Provides edible shoots for winter salads.  Can be grown with rye, wheat, or barley for support.
  • Buckwheat – Grows very fast in warm weather. Suppresses weeds and attracts pollinators when it blooms.
  • Daikon and fodder radishes – These have deep roots and are excellent for loosening compacted soil. Sown in the fall and allowed to die and decompose in the winter, leaving the soil porous.
  • Crimson and red clovers – Excellent nitrogen fixers. Attract beneficial insects and pollinators.  Planted in late summer or fall for incorporation in the spring.

Cover crops have much to offer the home gardener.  Use them to level up your soil management game!

by David Sumner, Hanover Master Gardener