Growing Pasture Under Trees on Small Acreage

A stand of mature trees cuts the light reaching the ground well below what a pasture grass needs, and thin, patchy forage under the canopy is the result. The USDA National Agroforestry Center puts the threshold plainly: for most ecosystems, canopy cover exceeding 50 percent leaves inadequate forage for grazing [3].

How much light is actually reaching the ground?

Light, not soil and not seed quality, typically sets the ceiling on what a treed acre can carry. The cheapest measurement available is a clear day and a notepad, with two or three spots watched for their hours of unbroken sun.

Kentucky bluegrass is best adapted to areas receiving at least 6 hours of direct sun a day, which makes that figure a workable line for full sun [2]. Below it you are in dappled light, where the sun comes and goes through gaps in the canopy.

Below 2 hours of direct sun, Iowa State recommends seeding 100 percent fine leaf fescue rather than a general lawn or pasture mix [2]. Heavy shade is where the honest answer stops being seed.

Under a closed canopy no cool season forage holds a grazable stand. The options there are usually thinning the trees, mulching the ground, or accepting a shade groundcover that nothing grazes.

Three light bands are enough to plan a seeding from:

• Full sun means 6 or more hours of direct sun, where any species on your zone list can fit [2].
• Dappled light means broken sun through canopy gaps, thinned stands, and the tree line edge.
• Heavy shade means under 2 hours of direct sun, where forage seed rarely pays for itself [2].

Which forage species tolerate shade?

Fine fescues, meaning red, Chewings, sheep, and hard fescue, along with rough bluegrass, are the most shade tolerant of the cool season grasses [1]. They also yield the least of the group.

Tall fescue is rated for moderate shade, and Kentucky bluegrass only for light shade [1]. Tall fescue takes hoof traffic and dry summers too, at 12 pounds per acre alone or 8 to 10 pounds with a legume [6].

Legumes are worth adding wherever the canopy opens enough to let light reach ground level. A Minnesota farm profiled by University of Minnesota Extension seeded white clover, chicory, and birdsfoot trefoil alongside timothy, tall fescue, meadow brome, and perennial ryegrass [4].

White clover is the legume to consider first, contributing nitrogen and protein under an open canopy, at 2 to 4 pounds per acre broadcast into existing grass [7].

Match each species to the light band you measured on the ground:

• Fine fescue for the darkest ground that still grows grass.
• Orchardgrass for dappled light and repeated grazing, at 8 to 12 pounds per acre alone [5].
• Tall fescue for the moderate shade and traffic of a lane or a gate corner.
• White clover wherever the canopy opens enough to light the ground.

How to seed under trees and get seed to soil contact

Small acreage rarely works in acres, so Penn State’s turf rates give the per 1,000 square foot figures you can weigh out, at 6 to 8 pounds of tall fescue and 4 to 5 pounds of fine fescue [8].

Broadcast seed is only as good as the contact it makes with soil. Rake the leaf litter back until mineral soil shows, then spread the seed in two passes at right angles so the coverage evens out.

Rake again, lightly, and firm the surface with a roller or your boots. Seed left sitting on undisturbed leaf duff dries out before its first root reaches mineral soil.

Soil chemistry matters as much under trees as in the open. Orchardgrass does best at a soil pH between 6.0 and 7.0 [5], and tall fescue reaches maximum productivity in the same band [6].

White clover wants a pH between 6 and 7 as well [7], so one lime decision usually serves the whole mix.

When should you seed under trees?

Early fall is generally the first choice across most of the country. Iowa State puts the best window for establishing a lawn from seed at mid August to mid September [2].

Soil is still warm, weed pressure has dropped off, and leaf fall has not yet buried the seedbed.

Under trees, fall carries a second advantage. The thinning canopy gives seedlings more light in their first month than the same ground receives in July.

If the fall window slips, late winter frost seeding is the usual backup. Freeze and thaw cycles in February and March honeycomb the soil surface and improve seed to soil contact [9].

Clovers respond best to that treatment, with white and ladino clover going in at 2 to 3 pounds per acre and red clover at 4 to 8 pounds per acre on pasture [9].

Which tree problems do you have to work around?

Black walnut is the one worth checking for by name. Its roots, leaves, and hulls carry juglone, a compound that yellows and stunts sensitive plants.

Penn State names the solanaceous vegetables, tomatoes, peppers, and potatoes, as the least tolerant, with rhododendrons and azaleas also sensitive [10]. Pasture grasses do not appear on that sensitivity list.

The practical steps under a walnut are keeping sensitive plantings past the root zone, 50 to 60 feet out from a mature tree, and raking leaves, hulls, and stems off the seeded ground [10].

Pines present a different obstacle, since an accumulated mat of needles sheds water and holds seed off the soil, so rake it thin before seeding.

Dense surface roots under maple and beech take water first, and the dripline, the ring of ground under the outer branches, is where competition often runs hardest.

How to graze without losing the stand or the trees

Stubble height carries more weight under shade, because a shaded plant has less leaf area to rebuild from. Penn State recommends leaving a 3 to 4 inch stubble on orchardgrass so the grass can recover quickly [5].

Tall fescue takes the same floor, no closer than three or four inches, with at least thirty days of recovery before animals return [6].

In open pasture, orchardgrass is grazed heavily and frequently, every 10 to 12 days, through the flush of spring growth [5]. Under a canopy, stretch that interval out and take less forage on each pass.

Three habits keep a treed pasture and its trees standing:

• Move animals off at 3 to 4 inches of stubble rather than grazing to bare dirt [5].
• Rest each paddock at least 30 days, and longer where light is short [6].
• Keep stock off saturated ground, and screen young trunks against bark stripping.

Light is the limit under trees, and it is the one thing you can measure before spending money on seed. Count the hours of direct sun, put fine fescue on the dark end and orchardgrass or tall fescue through the dappled middle, then add white clover wherever the canopy opens enough to carry it.

If you are seeding under an existing stand this season, Nature’s Seed can match a mix to your light level and your growing zone, so shop shade tolerant pasture mixes and pick your seeding window before the fall rains.

Sources

[1] Penn State Extension. Growing Turf Under Shaded Conditions. https://extension.psu.edu/growing-turf-under-shaded-conditions

[2] Iowa State University Extension. Seeding a New Lawn. https://yardandgarden.extension.iastate.edu/how-to/seeding-new-lawn

[3] USDA National Agroforestry Center. Agroforestry Note 46. https://www.fs.usda.gov/nac/assets/documents/agroforestrynotes/an46si09.pdf

[4] University of Minnesota Extension. Silvopasture. https://extension.umn.edu/agroforestry/silvopasture

[5] Penn State Extension. Orchardgrass. https://extension.psu.edu/orchardgrass

[6] Penn State Extension. Tall Fescue. https://extension.psu.edu/tall-fescue

[7] Penn State Extension. White Clover. https://extension.psu.edu/white-clover

[8] Penn State Extension. Turfgrass Seed and Seed Mixtures. https://extension.psu.edu/turfgrass-seed-and-seed-mixtures

[9] Penn State Extension. Frost Seeding for Forage Establishment. https://extension.psu.edu/frost-seeding-for-cover-crop-or-forage-establishment

[10] Penn State Extension. Allelopathy in the Home Garden. https://extension.psu.edu/allelopathy-in-the-home-garden