Winter-Killed vs. Overwintering Fall Cover Crops
By Ashleigh Smith
How to Plant Cover Crops
Cover crops are a fantastic tool to keep your garden in tip-top shape. But how should a cover crop be planted? The most common way of actually spreading the seed is by broadcasting. Broadcasting means you sprinkle the seed over your garden area without needing precise seeding distances. Occasionally a seed may be planted with the drilling method if you are seeding an entire field. How much seed is spread over a given area depends on the type of seed. We have included a guide at the end of this article to show you the seeding rates for each recommended fall cover crop.
As we mentioned in “Fall Cover Crop Planning” the first step in restoring and preserving soils is to select the best seed for your needs. If you want to address a specific problem, select seeds based on the benefits they provide. If you aren’t sure what problems need to be addressed, we highly recommend growing our All-Purpose Garden Cover Crop Mix. This mix includes plants from each cover crop category for the maximum number of benefits. Below we have matched up the benefits and route of action for each popular fall cover crop. Once you have selected the type of seed that will best help your garden, we recommend following the planting guide supplied below.
All-Purpose Garden Cover Crop Mix
Benefits of Overwintered Fall Cover Crops
Overwintered crops are planted in the fall and left to overwinter in the garden. These plants are not killed by the winter weather. Instead, they may go dormant and come back in the spring. These varieties require maintenance, such as mowing, when they put on vertical growth in the fall. To kill them in time for your spring planting, till into the soil to break up the root structures at least 2-3 weeks before planting cash crops in the late spring. You may till them into the soil before winter sets in; however, any seeds that have developed may sprout in the spring. If they do, you should till them back under to terminate before planting. Some perennial cover crops, such as White Dutch clover, can be grown as an intercrop groundcover. This means it is not tilled under. Instead, it grows in place to prevent erosion, supply nitrogen, and improve soil over time. This application is most popular for long-term crops like fruit orchards or growing on walking paths between crop rows.
Overwintering rice with a fall snow
Wheat sprouting in the spring with an early frost
Hairy Vetch
- Sow 4-6 Weeks Before the Fall Frost
- Perennial, Hardy to -40F
- Plant seed: 1/4-1/2 inch deep
- Seed Rate: 30-40 lbs/Acre
- Days to maturity/seed production: 60-300 Days (single season or overwinter)
Green Manure Benefits: Organic Matter Builder, Nitrogen Fixation, Weed Suppressant
Overwintering Benefits: Organic Matter Builder, Nitrogen Fixation, Ground Cover
Medium Red Clover
- Sow 4-6 Weeks Before the Fall Frost
- Perennial, Hardy to -30F
- Plant seed: 1/4-1/2 inch deep
- Seed Rate:20 lbs/Acre
- Days to maturity/seed production: 70-300 Days (Single Season or Overwintering)
Green Manure Benefits: Organic Matter Builder, Nitrogen Fixation, Weed Suppressant
Overwintering Benefits: Organic Matter Builder, Nitrogen Fixation, Ground Cover
Winter Rye
- Sow 4-6 Weeks Before the Fall Frost
- Annual, Hardy to -40
- Plant seed: 1/2 inch deep
- Seed Rate: 100 lbs/Acre
- Days to maturity/seed production: 330-345 Days
Green Manure Benefits: Organic Matter Builder, Weed Suppressant, Early Weed Suppressant (Plow before maturity in Spring)
Overwinter Benefits: Organic Matter Builder, Ground Cover, Erosion Prevention
White Dutch Clover
- Sow 5-7 Weeks Before the Fall Frost
- Perennial, Hardy to -30F
- Plant seed: 1/4-1/2 inch deep
- Seed Rate: 5-9 lbs/Acre Drilled 7-14 lbs/Acre Broadcast
- Days to maturity/seed production: 60-75 Days
Green Manure Benefits: Nitrogen Fixation, Pasture Forage, Can be undersown, Weed Suppressant
Winterkill benefits: Biomass Builder, Organic Matter Builder, Nitrogen Fixation
Field Covered in Snow
Benefits of Winter killed Crops
Winter killed crops are those that die under natural cold winter weather conditions. These crops are ideal for those who want to plant a fall cover crop and start their gardens as soon as possible the following spring. The seed is planted in the late summer to fall months, grows, and is naturally killed by winter temperatures. Tilling is not required if your frost will arrive before seeds develop. Otherwise, consider tilling before seeds mature to prevent volunteers from sprouting the following spring. If you use no-till or limited-till practices winter-kill crops are your friend. Like overwintering crops, winter-kill types can also be grown in the early spring. If grown in the spring, allow 2-3 weeks of rest after termination before planting your spring garden.
Peas cut as a green manure in the fall
Naturally composted plant material
Crimson Clover
- Sow 6-8 Weeks Before the Fall Frost
- Annual, Hardy to 0F
- Plant seed: 1/4-1/2 inch deep
- Seed Rate: 20 lbs/Acre
- Days to maturity/seed production: 70-90 Days
Green Manure Benefits: Nitrogen Fixation, Can be undersown, Attracts beneficial Insects
Winterkill benefits: Organic Matter Builder, Nitrogen Fixation, Ground Cover
Austrian Field Pea, Dundale Pea, Arivka Pea
- Sow 6-8 Weeks Before the Fall Frost
- Annual, Hardy to 0-15F
- Plant seed: 1.5-3 inches deep
- Seed Rate: 200 lbs/Acre
- Days to maturity/seed production: 52-75 Days
Green Manure Benefits: Nitrogen Fixation, Edible Tendrils, Pasture Forage, Weed Suppressant
Winterkill benefits: Biomass Builder, Organic Matter Builder, Nitrogen Fixation
Organic Oats
- Sow 8-10 Weeks Before the Fall Frost
- Annual, Hardy to 15F
- Plant seed: 1 inch deep
- Seed Rate: 100-140 lbs/Acre
- Days to maturity/seed production: 100-120 Days
Green Manure Benefits: Nurse Crop for Clover/Peas, Weed Suppressant
Winterkill benefits: Biomass Builder, Organic Matter Builder
Organic Daikon Radish
- Sow 4-10 Weeks Before the Fall Frost
- Annual, Hardy to 15F
- Plant seed: 1/2 inch deep
- Seed Rate: 8-10 lbs/Acre
- Days to maturity/seed production: 60-90 Days
Green Manure Benefits: Nutrient Miner, Pasture Forage, Weed Suppressant
Winterkill benefits: Biomass Builder, Breaks Compaction
| Planting Months | ||||
| Crop | Jul | Aug | Sep | Oct |
| Hairy Vetch | x | x | x | |
| Medium Red Clover | x | x | x | |
| Winter Rye | x | x | x | |
| Crimson Clover | x | x | x | |
| Mustard | x | x | x | x |
| Organic Oats | x | x | ||
| Pea | x | x | ||
| Radish | x | x | x | |
| White Clover | x | x | ||
| Yellow Blossom Sweet Clover | x | x |
Mustard
- Sow 5-8 Weeks Before the Fall Frost
- Annual
- Plant seed: 1/4-1/2 inch deep
- Seed Rate: 5-12 lbs/Acre Drilled 10-20 lbs/Acre Broadcast
- Days to maturity/seed production: 80-95 Days
Green Manure Benefits: Nutrient Miner, Suppress Pests, Weed Suppression
Winterkill benefits: Biomass Builder, Organic Matter Builder, Breaks Compaction