Preparing Your Site for Winter: Dormant Seeding Explained

Winter is upon us, and that means it’s time to ensure your project site is ready for the weather to come.

Refresher: In case you haven’t seen it, we have a blog post that goes over helpful general information for site winterization here.

Training Opportunity: There is a free training webinar on site winterization available through StormwaterOne here.
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When ice and snow melts and warm weather in the spring brings heavy rain, bare soils on construction sites are subject to erosion. As a result, sediment-laden runoff can enter storm systems and natural waterways if proper precautions are not taken. One of the best lines of defense for keeping soils in place is stabilization through temporary or permanent seeding. Yes, you can (and should!) stabilize idle sites (not going to be worked for >14 days) and sites that reach final grade in winter. 

WHAT IS THE TIMELINE FOR DIFFERENT TYPES OF SEEDING?

photo credit: Alekon pictures via Unsplashed

March 1st-August 15th: Oats, Tall Fescue, Annual Ryegrass, Perennial Ryegrass, Creeping Red Fescue, Kentucky Bluegrass*

August 16th-November 1st: Rye, Tall Fescue, Annual Ryegrass, Perennial Ryegrass, Creeping Red Fescue, Kentucky Bluegrass, Wheat*

Note: It is advised that seedings should not be made from October 1 through November 20. During this period, the seeds are likely to germinate but probably will not be able to survive the winter. For dormant seeding, it is advised to wait until temperatures consistently stay below 50 degrees F to prevent early germination. Temporary seeding/mulching techniques can be used until the dormant seeding window.

*Other approved species can be substituted

November 1st-February 29th: Mulching/temporary stabilization until temperatures consistently stay below 50 degrees F when dormant seeding can be implemented as a permanent solution.

This means if you are reading this article in November 2022, you have missed the normal growing season. Therefore, if your site has not been stabilized, you’re down to two options: mulching for temporary stabilization or dormant seeding for a permanent solution if areas have achieved final grade. 

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WHAT EXACTLY IS DORMANT SEEDING?
With this practice, the seeds will freeze and remain dormant during winter weather conditions. Then as spring weather emerges, the seeds will thaw and begin to germinate. This cycle follows what happens to seeds naturally during this time of year. This practice works great for the bare, exposed soil conditions that are often present at project sites that have recently achieved final grade. 

HOW IS DORMANT SEEDING DONE?
​Step 1 – Pick Your Seed
The timeline above outlines seeding practices in the Rainwater and Land Development Manual specifically for stabilizing construction sites for commercial, industrial, and/or residential purposes and at different times of the year. The USDA Natural Resources Conservation Service also provides a seeding table that outlines the grasses and legumes suitable for different uses and provides formulas for calculating seeding rates. This table can be found in the Ohio Field Office Technical Guide (FOTG) located here.

Step 2 – Prep
When soil conditions allow, prepare the seedbed, apply required amounts of lime and fertilizer.

Step 3 – Seed
Within the appropriate timeframe outlined above, apply seed mixture with cyclone seeder, drill, cultipackers seeder, or hydro-seeder.
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Step 4 -- Mulch
Mulch and anchor immediately after seeding. Acceptable mulch materials include straw, hydroseed, or erosion control matting/blankets.

ADDITIONAL INFORMATION
If you aren’t sure what stabilization practices will work best for your site during winter months, our team at Warren County Soil and Water Conservation District is happy to help. Feel free to give us a call at (513)695-1337.

ADDITIONAL RESOURCES:
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Rainwater and Land Development Manual 

Ohio EPA NPDES General Construction Permit 

Natural Resources Conservation Service