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 Cover crops are plants that are specifically grown for soil
protection and enrichment. They also reduce the use of
fertilizers (reducing cost), prevent soil erosion, minimize
weeds, improve soil structure, protect water quality, and as
they break down, add organic matter.
“Each year as home gardeners intensively grow vegetables in
their gardens, this depletes soil nutrients. Planting and
incorporating cover crops is one tool for getting them back,”
says University of Illinois Extension horticulture educator
Gemini Bhalsod.
Cover crops have been grown for hundreds of years to improve
soil quality, but their use was not widespread until the 1980s.
“Now it is not just organic and conventional farmers that know
the benefits of cover cropping, home gardeners are catching on
too, and you can even plant them in your raised beds,” Bhalsod
explains.
Legumes and grasses are the two most common cover crop groups.
Legumes fix nitrogen from the atmosphere into soils and grasses
uptake and consolidate nutrients in the soil that crops did not
use during the growing season. The nutrients are then
reintroduced when the plant is turned in. Root biomass also
contributes organic matter; loosens compact soils, improving
drainage; and increases water-holding capacity of sandy soils.
Which cover crops are best for gardens? “Most home gardeners do
well with planting a legume and grass mix,” she says. Winter rye
and winter wheat both germinate and grow in cool weather, and
winter rye is very cold tolerant. Early to mid-fall is a good
time to plant these. Legumes like hairy vetch, clover, and
winter peas need to be planted in late summer to early fall.
Consider combining at least one plant from both groups. Popular
mixes include winter rye and peas, or clover, vetch, and winter
rye.
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Many cover crops are killed by the winter cold, but
if they are given enough time to grow, they will still protect soil
through the winter. “Oats, radish, and peas won’t survive the cold
winter, but the dead plants act as mulch and can be easily
incorporated in the spring,” Bhalsod adds. Consider planting these
in the summer, after a spring harvest, or in between summer crops to
give them enough time to get established.
Winter-hardy crops will go dormant in the winter and
resume growth in the spring. “It’s important that plants like winter
rye, vetch, and clover are mowed down in the spring to stop growth
and prevent seed heads from forming,” Bhalsod says. Timing on this
is important – if cover crops reseed themselves, it can lead to
unwanted weeds.
Most cover crops can be planted right after harvesting vegetables.
Plant at least four weeks before consistent cold weather to allow
plants to establish before the winter. Large-seeded crops can be
planted in close rows, but small seeds can be broadcast. Be sure to
cover seeds with a small layer of soil and water well.
In the spring, Bhalsod recommends mowing the cover crop before it
sets seeds and then till it under.
“Plant residue needs to be tilled in two to four weeks before
planting vegetables, so allow enough time,” she says. “Breaking down
plant material requires nutrients, so it is important not to plant
vegetables until the residue has had a chance to break down.”
[News Source: Gemini Bhalsod
Terri Miller, MPA
County Extension Director - Unit 16]
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