Why Summer-Sown?

When the summer is your prime harvesting season (as it is for growers in the north), or your short rest before another growing season (as it is for growers in the south), it can be easy to marginalize anything other than cash crops in favor of the things that need your attention the most. But the summer can also be an ideal time to make investments in the long-term health of your growing space. In fact, if planned properly, summer soil health investments like cover crops can be low-maintenance and high value.
June is the tail-end of the sowing window for most summer-established cover crops here in the northeast, but there are still plenty of options that give big value if they’re sown in June or planned appropriately for later in the summer.
Buckwheat is usually the star of summer cover crops, taking just 30 days to start bringing benefits to your soils. It’s a great option for those without a plan, especially if soil is left bare after a harvest with no planned succession. Simply broadcast some buckwheat over your bare soils and wait just a few days to start seeing green. (The bees will thank you later, too.) Field peas, oats and phacelia can also do wonders in just a few weeks.
Read on for full details on how to perfect your summer-sown cover crop plan.

The Steps: Planning, Establishment, Incorporation

There are three steps to maximizing the benefits of cover crops: 1) planning, 2) establishment, and 3) incorporation. Before sowing any cover crops, make sure you have determined your goals for each of these steps so you can get the biggest benefit from your crop.
Planning begins with understanding your soils. The top reason growers utilize cover crops is to help build their soil health for the long-term. For a crash course on how to plan for optimal soil health, check out our blog post on Mastering the Art of Soil Nutrients. The goals you establish based on your soils’ needs will help you determine which type of cover crops you want to plant where.
Use this chart to help you determine which of the following summer-sown cover crops you need to boost your soil health:
Crop Green Manure Benefits Winterkill Benefits
Annual Ryegrass Nurse crop for legumes Weed suppressant Organic matter provider (when mown) Biomass builder Organic matter provider
BMR Sorghum-Sudangrass F1 Silage or pasture forage Breaks up compacted soils Organic matter provider (when mown) Weed suppressant Biomass builder Organic matter provider
Common Buckwheat Breaks up compacted soils Attracts beneficials Weed suppressant Organic matter provider
Oats Nurse crop for clover and peas Weed suppressant Biomass builder Organic matter provider
Phacelia Attracts beneficials Weed suppressant Biomass builder Organic matter provider
Winter Rye Organic matter provider (when mown) Weed suppressant Early weed suppressant (must be plowed under before reaching full maturity in the spring) Winter-hardy perennial Maintains soil structure Prevents run-off
Field Peas Nitrogen fixation Edible tendrils Pasture forage Weed suppressant Biomass builder Organic matter provider Nitrogen fixation
White Clover Nitrogen fixation Pasture forage Can be undersown Weed suppressant Biomass builder Organic matter provider Nitrogen fixation
Sweet Yellow Clover Nitrogen fixation Nutrient miner Attracts beneficials Biomass builder Organic matter provider Nitrogen fixation
Establishment is determined by the specifications of the crop type you select. Not all cover crops grow at the same rate, or in the same season, or in the same soil conditions. For details on each cover crops needs, visit the individual product pages on our website, linked in the charts below.
Use this chart to determine your ideal timeline for summer-sown cover crops based on the variety selections you made in the planning phase:
Crop Mar Apr May Jun July Aug Sept Oct
Annual Ryegrass

X

 X X X

X
BMR Sorghum-Sudangrass F1

X

 X X X X
Common Buckwheat X X X X
Oats

X

 X X

X
Phacelia

X

 X X

X

X
Winter Rye X

X
Field Peas

X

 X X X
White Clover

X

 X
Sweet Yellow Clover

X

 X
The following chart details seeding rates and depths, and soil temperature requirements for summer-sown cover crops:
Crop Seeding Rate Seeding Depth Soil Temp. for Germination
Annual Ryegrass   10-20 lbs/acre drilled, 20-30 lbs/acre broadcast ½” deep 40°F or warmer
BMR Sorghum-Sudangrass F1   35 lbs/acre drilled; 40-50 lbs/acre broadcast 0.5-1.5” deep 60°F or warmer
Common Buckwheat   35-135 lbs/acre ¼-½” deep 50°F or warmer
Oats   100-140 lbs/acre 1” deep 38°F or warmer
Phacelia   7-12 lbs/acre ¼-½” deep 37°F - 68°F
Winter Rye 100 lbs/acre ½” deep 33°F or warmer
Field Peas   200 lbs/acre 1.5-3” deep 40°F or warmer
White Clover   5-9 lbs/acre drilled; 7-14 lbs/acre broadcast ¼-½” deep 41°F or warmer
Yellow Sweet Clover   8-15 lbs/acre drilled, 15-20 lbs/acre broadcast ¼-½” deep 42°F or warmer  
Incorporation is key to the whole cover cropping process. Although many farmers inherently focus on hitting sow dates and worry less about hitting or missing incorporation dates, the mowing or killing of a cover crop can create ideal biomass development, and minimize your seed bank deposits and material breakdown when timed correctly.
Use this chart to help you determine how and when to incorporate your summer-sown cover crops based on the variety selections you made in the planning phase:
Crop Life Cycle Days to Seed Set Incorporation
Annual Ryegrass   Annual 50-70 days Mow for maintenance, plow under to kill
BMR Sorghum-Sudangrass F1   Annual 90-100 days Mow, or allow winter kill
Common Buckwheat   Annual 35-42 for blooms, 70-84 for grain Mow, or allow winter kill
Oats   Annual 100-120 days Mow, plow under, or allow winter kill
Phacelia   Annual Flowers only when days reach 13+ hours Mow, plow under, or allow winter kill
Winter Rye Perennial (hardy) 330-345 days Mow or plow under
Field Peas   Annual 52-75 days Mow, or allow winter kill
White Clover   Perennial (tender) 60-75 days Mow for maintenance, plow under to kill
Yellow Sweet Clover   Biennial 60-70 days Mow or plow under
Looking for other cover crop planning tools? Check out our complementary blog post about fall-sown cover crops.