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It’s Time for Frost Seeding Legumes

By   /  February 22, 2016  /  3 Comments

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If you have any frost-seeding of legumes to do, now is the prime time to get it done. It is important to try and get some seed to soil contact if possible when broadcast seeding. This can be accomplished by carefully grazing the forages down more than normal prior to seeding, using a toothed harrow to help scratch the seed in, or utilizing your existing livestock to help trod it in. All three methods can produce positive results.

Consider Clover

Here are just a few examples of clovers.

Here are just a few examples of clovers.

Clovers are probably the easiest legumes to frost-seed. The seed is small and slick and easily moves down through the residue/residual to the ground. If you already have some clover and are just enhancing what you have, then utilize improved varieties for the best results. If you don’t have any clover presently, then you should inoculate the seed with the appropriate rhizobium. The seed may germinate and thrive without it, but it will do so much better if it is present, especially if one of the goals for planting the legume is as a nitrogen source for the grass component of the stand

It is best to get a seeding recommendation and rates for the legumes from your local soil and water conservation district office or extension office. Some legumes do better with particular types of livestock over others, some do better depending on the type of soil and drainage, and there are some differences depending on management. Red clover for example is better suited for hay than most white clovers because it dries better. There is also a huge difference in seed size which highly influences the amount of seed that is needed. Most white clovers have over three times more seed per pound than red clovers. It is easy to seed too much white clover and seed size is part of the reason.  That can be a problem because white clovers (Dutch whites, Ladinos, Alsike, etc.), can cause bloat issues when they dominate a stand.

This is just one example of the difference between raw seed (left) and coated seed (right). Photo courtesy of New South Wales Primary Industry Department (Agriculture).

This is just one example of the difference between raw seed (left) and coated seed (right). Photo courtesy of New South Wales Primary Industry Department (Agriculture).

You can buy clover seed coated too. Coated seed has a coating of clay material surrounding the seed which actually helps you be able to sow very small seed more accurately. It does change the pounds of bulk seed you are planting. Most coating adds about 33-34% inert ingredients to the bag of seed. So if you are wanting to plant six pounds of red clover, you are actually going to have to increase the amount of bulk seed you plant per acre to about nine pounds per acre to get your planned six pound rate. Most legumes have good germination and purity rates normally, but that does vary some. The inert ingredient percentage needs to be accounted for with the purity. For example a lot with 98% germination and 97% purity with 33% inert (the coating) .98 x .97 x (1-33% or .67) = .63 (or 63%) of the lot is live seed. So if the desired pure live seed rate is six pounds per acre, 6 / .63 = 9.5 pounds per acre. When it comes to something like a Ladino clover and you are wanting to seed only about a pound per acre in some cases, coated seed makes it a lot easier to do.

Coated seed can also be the carrier of the inoculant if needed and occasionally has other things included. If you really need the inoculant, the seed needs to be used the same year it was coated. Quite a bit of legume seed has a calcium carbonate coating which can create a slightly better environment pH wise for the sprouting seed, but for the plant to thrive and do well, low pH soils should be limed at least six months in advance to create the environment best suited for the legume being present. Most clovers like a soil pH of 6.2 to 6.8 with preference on the upper end of that range.

Add Legumes Because….

I can't overemphasize that clover can be seeded too thickly and get too dense. Too much clover can mean serious bloat issues!

I can’t overemphasize that clover can be seeded too thickly and get too dense. Too much clover can mean serious bloat issues!

There are lots of reasons to add legumes to your pastures and hay fields and I won’t go into a lot of detail but just mention a few. Diversity is always good and rarely do you find a monoculture in nature. The synergy and relationship between grasses and legumes is always positive and they provide benefits to each other. The mix of legumes and grasses helps to boost yield from nitrogen produced by the legume and the combination provides more grazing than either one by itself. The clover fills in the gaps or voids in a grass stand. Some legumes can persist under drier conditions than cool-season grasses during the summer. The legumes can provide a significantly high amount of the nitrogen needed for the grass in the stand and boosting its yield and thus quality. Legumes can also be a good pollinator plant for bees. Legumes generally are higher in quality than most grasses at the same stage (crude protein, nutrients, and digestibility).

Legumes are good to dilute stands of endophyte-infected tall fescue and some new research indicates that a tannin in red clover might actually help offset the toxin in endophyte tall fescue. I’ll be following up on this.

And About that Residue/Residual

ResidueVSResidualEarlier I included residue/residual in a statement and there is a reason I did that. Just recently, Jim Gerrish’s article last week in On Pasture noted that we need to be more careful of the use of these two words in regards to the forage left in the pasture after a grazing episode. I totally agree and thought this statement was excellent! I try to stick to these same definitions and if I have ever deviated from this, I apologize.

So, with that said, how is the residue and residual in your pastures today?

Keep on grazing!

natglc-logo-1Thanks to the National Grazing Lands Coalition for making this article possible. Click on over to see the great work they do for all of us. Thank them for supporting On Pasture by liking their facebook page.

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About the author

For more than 25 years, Victor Shelton, Indiana agronomist and grazing specialist with the Natural Resources Conservation Service, has provided advice about grazing’s best practices. He travels across the state conducting pasture walks, working one on one with farmers and participating in grazing talks. He also writes a newsletter called "Grazing Bites" as a way to talk about current and seasonal grazing issues and what farmers need to be prepared for.


  1. Randi Calderwood says:

    I am located in NE VT with grass land at 1200-1800 feet. The ground is bare now but we have a solid 6 wks of winter and nights in the single digits.

    Is it too early to frost seed?

    How long will the seed last on top of the ground?

    • Victor Shelton says:

      There is always a chance of some seed laying for a long time being consumed by birds, rodents, etc., but most clovers being such a small smooth seed, normally thrive quite well being seeded during the dormant season awaiting the right conditions to germinate assuming everything else is adequate.

    • Bruce Howlett says:

      It is not too early (you could start in late fall), and frozen ground means that you can drive around with minimal soil damage. However, consider the question of why you might want to frost-seed. If you don’t have any clovers because low soil pH and/or low K levels (both are common in our area) are killing off the legumes, spreading more seed won’t have much effect. If you don’t have recent soil test results, you might want to hold off until you can take some to find out whether any soil amendments are warranted.
      (NRCS-VT Berlin Field Office)

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