Companion and Cover Crops

Heidi Kratsch, Area Horticulture Specialist

Companion crops:◦ Also called Intercropping◦ Usually planted at the same time as production

crops (interplanting vs. perimeter planting)◦ Planted most often for pest suppression

Cover crops:◦ Usually planted in the “down” season (such as

winter) – not harvested for consumption◦ Used for soil enhancement (called “Green

Manure”)

What’s the difference?

But there is some overlap!

Structural support for vining plants Increase nitrogen balance in the soil Pest suppression (insects) Pollinator / predator recruitment Protective shelter Trap cropping Pest pattern disruptions

Companion crops can provide:

Trap cropping Plants such as sweet allysum have been used to lure the

diamondback moth from cabbage plants.

Destroy the trap crop after it becomes infested with insects.

Diamondback moth feeding on cabbage

Sweet alyssum used as a trap crop

Legumes:◦ Alfalfa◦ Beans – all kinds◦ Clover◦ Lentil ◦ Peas

Interplanted with heavy feeders:◦ Cabbage◦ Cauliflower ◦ Celery◦ Corn◦ Cucumbers ◦ Leeks◦ Lettuce◦ Spinach◦ Squash◦ Tomatoes

Symbiotic nitrogen fixation

Interplanted rows of corn with clover

French and African marigolds release thiophene.

Thiophene repels nematodes, grubs and aphids.

Biochemical pest suppression

Mowed cereal rye as a mulch to suppress weeds.

Use with vegetables that have large seeds or are transplants.

Cut at flowering but before seed set.

Plant allelopathy

Results in a diverse canopy

Taller sun-loving plants shade lower shade-loving plants ◦ Such as lettuce,

spinach, celery

Physical spatial interactions

Interplanting corn with squash to confuse squash insect pests.

Companion plants provide food and cover for beneficial insects.◦ Ladybird beetles◦ Lacewings◦ Hoverflies◦ Praying mantis

Beneficial habitatsSweet alyssum

Fennel

Diversify plantings

Planting multiple crops and varieties insures that you have something to harvest at the end of the season.

Mixed planting of broccoli cultivars to reduce aphid infestation

Sensitive crystallization-Ehrenfried Pfeiffer

Extract from valerian root leaves

Shady location Sunny location

Wampanoag (Northeast and South)

Hidatsa (Plains)Zuni waffle garden (Southwest)

U.S. Native American farming practices

Corn, beans and squash have played a key role in the survival of all North American people.

Gifts from Great Spirit

Collectively called De-o-ha-ko, or “those who support us”

Three Sisters Method

Term coined by the Iroquois in the NE U.S. and Canada

Corn provides structure for beans to climb

Beans replenish the soil with nutrients

Leaves of squash and pumpkin create a living mulch that conserves water and inhibits weeds.

Science behind the method:

Evidence of Paradise, Quilt created by M. Joan Lintault to celebrate Iroquois farming methods.

Circular Wampanoag garden

N

Hidatsa garden designN

Zuni waffle gardenN

Growing two or more vegetables in the same place at the same time

Companion interplanting

Radishes are harvested before they crowd the carrots.

Time to maturity

Plant small plants close to large plants.

Can use this strategy to lengthen the season for cool-season plants.

Aboveground growth pattern

Interplanting broccoli and lettuce

Root growth pattern

Plant shade tolerant species in the shadow of taller crops.

Light requirements

Interplanting cabbage, lettuce, celery and mustards

Interplant heavy feeders with less demanding crops.

Nutrient requirements

Peas growing vertically behind 3 cauliflower plants. Growing in-front of cauliflowers are leeks, carrots and lettuces.

Combine plants with similar water requirements.

Water requirements

Cucumbers, zucchinis and squash have similar water requirements.

Increase soil organic matter

Increase nitrogen balance in the soil

Suppress pests (weeds)

Provide habitat for beneficial insects

Enhance soil biological activity

Control erosion Prevent compaction

Cover crops can:

What do you want your cover crop to do?

Legumes Fix nitrogen and add

organic matter Peas, clovers

Cereal grains ◦ Fast-growing: add

organic matter and control erosion

◦ Deeply tap-rooted plants: relieve compaction

◦ Cereal rye, winter wheat, barley

Which crop(s) should I plant?

“Bio-drilling” relieves compacted soil

In rotation: 2- or 3-year

Winter cover crop Summer cover

crop Strip cropping Intercropping

Ways to use cover crops

Cowpea as a summer cover to increase soil nitrogen levels and suppress weeds

Drought tolerant Excellent mineralized

N provider Grows slowly in fall

but resumes in spring Smothers spring

weeds Enhances soil

moisture retention Sprawling vines can

be a challenge

Hairy (winter) vetch (Vicia villosa)

Winter annualZone 3 - 6

Great in an area where tomatoes or corn will be grown!

Early September Seeding rate of 1-2

lb./1000 ft2

Requires inoculation with Rhizobium bacteria

Comes as dry powder mixed with finely ground peat moss

How to plant…

Winter annual that may die in winter in colder parts of Nevada

But, establishes quickly

If winter-killed, no need to pull up…

Can combine with winter rye

Austrian winter pea (Pisum sativum subsp. Arvense)

Seed Austrian pea at 2-4 lb./1000 ft2

Winter annualZone 6

Greater control of winter annual weeds

More organic matter residue

Provides proper C:N ratio to speed decomposition in soil

Use 40-60% grain full rate and 80% legume full rate

Mix annual legume with cereal grain for added benefits

Hairy vetch with winter rye

Hardiest of cover crops

Rapid establishment Deep fibrous rooting Builds organic matter Breaks up compaction Allelopathy

suppresses weed seeds

Often grown with a legume

Winter rye (Secale cereale)

Winter annualZone 4

Seed at 2.5 lb/1000 ft2

Fall-seeded brassica Forms thick, white tap

roots 8-14 inches long! Nicknamed “biodrill” or

“tillage radish” Seed in late August, will

winter-kill in much of Nevada

Traps soil nutrients, breaks up compaction, biofumigant properties (against nematodes)

Forage radish (Raphanus sativus)

The best time to plant a cover crop is anytime a bed is not covered by food crop or mulch.

Make a furrow for large seeds

Scatter and rake in smaller seeds

Tamp the bed to ensure good soil contact and water in.

Cover crop management

Nature abhors a vacuum. Bare ground invites weeds and represents a lost opportunity to improve the soil.

Choose crops appropriate for our area.

Irrigate only enough to avoid plant stress.

Use drip irrigation to avoid water waste.

Irrigate less in winter.

Irrigating cover crops

While buckwheat is a fast-growing summer annual cover crop, it requires more water than is efficient for our region.

Do not harvest cover crops…

Incorporate them back into your soil

Tilling – avoid deep mechanical tillage

Mowing Remove plants and use

as compost or mulch Pen chickens in the field

(except hairy vetch – seed is poisonous to chickens)

Incorporate cover crop 3 weeks before food crop is planted

Incorporating a cover crop

Turning in a cover crop by hand is a tedious job. Top mowing or use of a garden tiller can facilitate the process.

Before and after chickens…

Chickens can remove a cover crop in 2 weeks. BUT don’t let chickens graze in hairy vetch that has done to seed.

Perennials – alfalfa, hairy indigo, red clover*

Summer annuals –garden pea, mustard, turnip, barley, oats, sorghum-sudangrass

Winter annuals – Austrian winter pea, hairy vetch, winter wheat, winter rye

Types of cover crops

* Can be weedy in a garden setting

Medium red clover*

Food Crop Cover Crop

Early spring planting: Lettuces, cabbage, spinach, kale, peas, radishes, carrots, chard

Fall planted winter annual that is winter-killed: Austrian winter pea

Warm season planting: peppers, tomatoes, squash, corn, melon

Fall-planted cold-hardy legumes: hairy vetch

Late-season planting: Broccoli, beets, kale, collard, lettuce, peas, radishes

Spring-planted summer annual: garden pea, clover

Sample cover crop sequence

Territorial Seed Companyhttp://www.territorialseed.com/category/cover_crops

Johnny’s Selected Seedshttp://www.johnnyseeds.com/t-covercropchart.aspx

Burpee Seedshttp://www.burpee.com/organic-gardening/cover-crops/

Peaceful Valley Farm Supplyhttp://www.groworganic.com/seeds/cover-crop.html

Sources for cover crop seed

FREE download

http://www.sare.org/Learning-Center/Books/Managing-Cover-Crops-Profitably-3rd-Edition

Questions?