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Native Cover Crops & Wildflowers for Soil Health

  • Writer: Chris Musser
    Chris Musser
  • Oct 6
  • 5 min read

Updated: Oct 6

The practice of planting soil-enriching crops between harvests is ancient and practiced throughout the world. Chinese manuscripts describe intricate crop rotations, intercropping, and the use of green manure. In Greece and Rome, farmers sowed clover and vetch between rows of vines and olives to restore fertility, and by the 1700s, European farmers were using lupines and peas to rejuvenate sandy or exhausted soils. These crops crossed the Atlantic with settlers and became staples of early American agriculture, to rest and rebuild the soil that fed wheat, corn, and orchard crops.


Farewell-to-Spring (with poppies and red orach)
Farewell-to-Spring (with poppies and red orach)

Today, gardeners still rely on many of those same European species of rye, peas, and clover to cover and nourish the soil. But the Pacific Northwest has its own plants that can do this work just as well, while providing even more ecological benefits.


Native clovers, lupines, sedges, and wildflowers enrich the soil, prevent erosion, and attract pollinators adapted to our local climate. Unlike traditional cover crops, they thrive in our native soils and rain-fed sites, support native bees, butterflies, and soil organisms.


Soil Builders


These plants improve soil fertility, fix nitrogen, and help hold the soil in place during our rainy winters.

Large Leaf Lupine in my front yard
Large Leaf Lupine in my front yard

Nitrogen Fixers

Nitrogen is one of the three primary nutrients plants need to grow (along with phosphorus and potassium). It fuels leafy growth and chlorophyll production. Most plants can’t access nitrogen directly from the air, even though it makes up about 78% of our atmosphere but nitrogen-fixing plants can. 


  • Nitrogen-fixing plants form nodules on their roots that house Rhizobium bacteria. The bacteria convert atmospheric nitrogen (N₂) into ammonia (NH₃) and related compounds that plants use to build proteins and chlorophyll.

  • Some nitrogen leaks from the nodules as the plant grows. Root exudates and sloughed-off root hairs release nitrogen compounds into the soil, where nearby microbes and neighboring plants can absorb them.

  • When nitrogen-fixing plants die back, soil organisms break down their leaves, stems, and roots. The nitrogen stored in that biomass becomes ammonium and then nitrate, which easily dissolves in soil water and moves to other plants’ roots.

  • Mycorrhizal fungi and free-living soil bacteria can also transport nutrients between root systems. In healthy soils, these networks share nitrogen and other nutrients long before decomposition.

  • Over time, repeated cycles of growth, mowing, and decomposition build a reservoir of organic matter and slow-release nitrogen in the topsoil.


Pacific Northwest Native Nitrogen Fixers


Native Grasses & Sedges

Grasses and sedges are the quiet workhorses of landscape. Under the soil surface, their roots build soil, conserve water, and provide structure for the rest of the ecosystem.

  • They hold soil in place: Native grasses have dense, fibrous roots that prevent erosion during rainy Portland winters and stabilize slopes, pathways, and planting beds.

  • They build living soil: Perennial grasses shed fine roots that decompose in place, feeding soil organisms and creating a deep, spongy structure that holds water and supports mycorrhizal fungi.

  • They balance fertility: When paired with nitrogen-fixing clovers and lupines, grasses capture and store the nutrients those legumes release. Together they mimic natural meadow systems — legumes add nitrogen, grasses hold it in the root zone.

  • They’re tough and beautiful: Once established, most native grasses need little or no irrigation. Their subtle movement and texture add calm and continuity to a planting, tying together showier wildflowers and shrubs.

  • They support the whole system: Grasses provide habitat for beneficial insects, nesting material for birds, and moderate soil temperatures. In both gardens and restoration areas, they form the backbone of resilient plant communities.


Regional standouts include:


Living Mulches

These plants don’t build nitrogen like legumes, but they cover bare soil, reduce weeds, and provide long-term living mulch.


Pollinator Companions

These natives may not act like classic cover crops, but feed and provide habitat for wildlife.



Making a Mowable Native Lawn


A functional, mow-tolerant native lawn needs plants with fine foliage, flexible stems, and low growth habits that stay attractive under light foot traffic and occasional mowing. The following are available at East Portland Plant Buying Club.


Grasses

  • Molate red fescue (Festuca rubra var. ‘Molate’) Creeping red fescue that knits into a soft, fine-textured carpet.

  • Prairie junegrass (Koeleria macrantha) Bunch-forming and drought-tolerant; adds texture and early-season growth.

  • Western fescue (Festuca occidentalis) — Fills gaps and tolerates periodic mowing.


Legumes

  • Small-headed clover (Trifolium microcephalum) — Compact, self-seeding, fixes nitrogen.

  • Foothill clover (Trifolium ciliolatum) — Adds seasonal fertility and a touch of spring color.


Living Mulch Companions

  • Dwarf yarrow (Achillea millefolium var. ‘Yaak’) forms a soft, walkable mat and blooms lightly if mowing is skipped.

  • Creeping thyme (Thymus serpyllum) low-growing,, aromatic, fills sunny gaps and tolerates occasional foot traffic.

  • Meadowfoam (Limnanthes douglasii, L. alba var. ‘Red Viking’) sunny flowering annuals that fill in winter bare spots and feed early pollinators.


Establishment Tips

  • Prepare a clean seedbed: Remove weeds and loosen the top ½ inch of soil.

  • Seed rate: About ½ oz per 300 sq ft.

  • Timing: Sow after the first fall rains; light watering helps even germination.

  • Maintenance: Mow once or twice per year to 3–4 inches. In drier sites, let the fescues and clovers go semi-dormant rather than overwatering.


This combination produces a fine-textured, mostly evergreen groundcover that’s soft underfoot, drought-tolerant, and full of life — a true native “lawn” alternative that stays tidy without constant mowing or fertilizer.



 
 
 

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