What Your Grass and Cover Crop Seeds Need to Succeed

To plant a seed may be the ultimate sign of faith and hope. To give it the proper conditions to thrive takes action on our part.

Jim Johnson, Noble Research Institute’s Senior Regenerative Ranching Advisor, says working to build the right conditions in your soil will help increase the odds of successful germination and growth.

“Building healthy soil is something we work at every day, all year long,” Johnson says.

Whether you’re planting a cover crop for the first time or trying to add diversity to your pastureland, new seeds need have the same requirements for a good start: viable seed, good seed-to-soil contact, adequate moisture, proper temperatures and available oxygen.

“Those aren’t necessarily things that you can just take care of the day you decide to go plant,” Johnson says. “They’re soil management actions that we take every day.”

START WITH THE BEST FOR THE BEST SUCCESS

Start with a high-quality, vigorous seed.

“A vigorous seed is going to be more forgiving if conditions are less than ideal,” Johnson says. A laboratory can conduct a cold germination test or a stress test on seed to give you a good idea of its viability.

If comparing seeds of the same species, look at the number per pound. If one rye cover crop has 26,000 seeds per pound and another of the same variety has 16,000 seeds per pound, you know the 16,000-seeds-per-pound mix comes with bigger seeds.  

“You want big, plump seeds for that variety, because the bigger and plumper seeds typically have more of the stored energy they need to get started,” he says.

MAXIMIZE SEED-TO-SOIL CONTACT

The seed must soak in moisture from the soil in order to soften and swell for germination. If you visualize each seed as a cube, you’ll see that broadcasting the seed on the soil’s surface only connects one side to the soil. Push the seed down a little, and portions of the cube sides will touch the dirt around it. If you push it down and can then firmly cover it with soil, all six sides have an opportunity to connect, but only if the soil structure is in good condition.

Very compacted, hard soil will present challenges to getting the seed into the ground and getting the soil to close back around it. Loose, fluffy soil is filled with air gaps and spaces that prevent seed-to-soil contact. You want to plant into highly friable soil that crumbles easily when squeezed or crushed – the consistency of cottage cheese or a moist chocolate cake. That is what gives the seed its best chance for success.

Ground cover will help build more friable soil, but too much residue may prevent adequate seed-to-soil contact. A well-calibrated, well-maintained no-till drill can plant through tons of pounds of residue. If you’re broadcasting seed into grass or a crop field with residue, Johnson suggests using livestock to graze or remove excessive cover before broadcasting. When used correctly, high-density, short-duration livestock exposure can help ‘tread’ broadcast seed into the soil, too.  

If incorporating livestock is not an option, consider some other limited, well-timed disturbance to help get the seed in touch with the soil. A quick pass with a disc to chop and break up residue while incorporating the seed, or burning residue just before seeding, can help give new life a fresh start.

ADEQUATE MOISTURE MATTERS

The success of the seed-to-soil contact also rests on having adequate moisture in the soil to reach the seed. Generally, at least a quarter inch of precipitation is needed for the seed to germinate, plus another quarter or half inch for the plant to establish.

A good, well-timed rain is the quickest path to success, but encouraging diverse root systems in the ground over the long term promotes a moist, fertile environment.  

“We always have to be thinking about how we can set the soil up to absorb and hold water,” Johnson says. Heavier residue will help retain moisture and protect the surface from evaporation, and living roots below ground open up pore space in the soil for water to find its way in.  

Healthy soil that holds moisture will help insulate a seed waiting for rain. If you see noticeable erosion on your land, you know the water cycle is broken. Keep the ground covered to slow water down and help it soak into the soil.

KEEP THE TEMP JUST RIGHT

Many seeds can tolerate soil temperatures from just above freezing up to the low hundreds but an ideal range for germination is typically 65 F to 85 F. You’ll need to be confident that soil temperatures will remain in a range acceptable for that particular seed for at least three or, more ideally, five days in a row. Forecast of a favorable trend can work, too.

“If we’re planting a cool season crop in the fall, we might be able to plant into soil we know is too hot to germinate,” Johnson says. “But if the days are getting shorter and cooler, and we have a little rain in the immediate forecast, we’re trending in the right direction.”

Timing always matters, but your window for success in the temperature department will widen as your soil health increases.

“We know we can plant earlier or later if we have good, healthy soil,” he says. Healthy, covered, root-filled soil maintains a more consistent temperature, regardless of environmental temperature.  

GIVE IT ROOM TO BREATH

Waterlogged or compacted soils often starve seeds of the oxygen they need to thrive. A heavy rain may soak a seed and prompt germination, but the seed will drown if underwater for more than a couple of days.

Often, one problem leads to another. Wet soils are prone to compaction. Try to keep animals and machinery off water-logged ground, especially before planting. Again, the proper amount of ground cover will help mitigate the downsides of compaction.

To demonstrate the positive impact of ground cover on reducing compaction, Johnson often lays his hand on the ground during Noble’s Land Essentials course and invites the biggest student in the course to stand on it. But first, he gathers up plant residue and litter and covers his hand.

“It’s a pretty powerful demonstration when they can stand on my hand, and I hardly feel it,” Johnson says. “That’s how big a cushion residue makes for our soil surface.”   

Preventing compaction, increasing organic matter and promoting good water absorption can also help prevent the soil surface from crusting over a seed, another possible impediment to seeding success.

“All these things matter and make a difference in your seed germination,” Johnson says, “Healthy soil with good soil structure is easier to plant into, easier to get all the conditions your seed needs to germinate and establish, and easier to get a good stand in.” Unpredictable weather can still throw a wrench into even the best-laid plans, but proper soil conditions give your seeds their highest chance of success whether you drill or broadcast your new forage crop.

Laura Nelson

Laura Nelson is an agriculture journalist, author, and farm and ranch photographer based in western Nebraska. When she’s not writing or researching for her next book project, she’s tending her garden, helping on her family’s farm and ranch, curling up with a good book, or staking a claim in the front row of a music festival.

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