California & Oregon Cover Crop Mix Calculator | Weaver Seed
Weaver Seed · Cover Crop, Forage & Custom Seed Mix Tool

California & Oregon Cover Crop Mix Calculator

Build and evaluate a custom cover crop seed mix for California or Oregon using your crop system, planting window, rainfall or irrigation, soil conditions, management goals, seeding method and termination plan. The tool also supports forage, pasture, erosion-control, orchard, vineyard and specialty seed mixtures. Start with the few inputs that materially change the recommendation; open Advanced Settings only when the job requires more detail. The calculator keeps the formulation under your control while stress-testing seeding rate, field fit, planting depth, physical compatibility, termination, water competition and functional coverage. It separates agronomic stand-equivalent function from seed-weight composition and uses California, Oregon and Western agronomic evidence to screen planting windows, crop-specific nutrient and pest concerns, cultivar fit and residue C:N behavior. It can decline to build a starter mix when the information provided does not support a defensible automatic recommendation.

1 · Define the jobUse, date, water and priorities
2 · Build the mixAdd species or create a starter mix
3 · Stress-test itReview risks, rate and Weaver mix matches
Select the state first. The calculator then applies region-specific planting-window and adaptation logic.
Used to adjust regional confidence; NOAA frost history and actual field conditions still override broad regional assumptions.
USDA-NRCS guidance notes that mixes with very different seed sizes and depths establish more reliably when large and small seed can be metered or placed separately.
Seed and coating availability is lot-specific and must be confirmed before quoting.
Optional: seed requirements, termination, livestock, soil detail and next-crop constraints.

Field & Management Context

Primary use, rainfall, water availability and your top goals drive the first-pass ranking. Orchard and vineyard geometry appears only when relevant. Advanced settings refine the stress test; the calculator never silently changes your formulation.

Optional field-location intelligence
Use approximate field coordinates or your device location in California or Oregon to screen observed rainfall/frost history and modeled topsoil texture/pH. Before any lookup, coordinates are rounded to about 0.001° (roughly 100 m), used only for this browser session, not saved with mixes, and not included in Weaver review summaries. Analyze Location sends the rounded coordinates directly to NOAA/NCEI and SoilGrids. Nothing is applied silently. Salinity, drainage and field soil tests still override map estimates.
No location analysis yet.
Climate screen: NOAA/NCEI observed station data. Soil property estimates are derived from SoilGrids / ISRIC – World Soil Information (CC BY 4.0), modeled at approximately 250 m. Verify important soil decisions with field testing and USDA-NRCS Web Soil Survey.
Use tissue analysis, crop history, or advisor assessment when available. This changes cover-crop N-fixer weighting; it is not a fertilizer-rate recommendation.
Vine vigor is intentionally separate from nitrogen status.
Devigoration is appropriate only where vigor is genuinely excessive and the site can tolerate added competition.
Young vines are more sensitive to cover-crop competition.
Nematode host status is species- and rootstock-dependent. The calculator uses only broad evidence-supported screening rules and flags situations that need field-specific diagnosis.
UC guidance shows substantially different nitrogen demand between on- and off-years; use orchard records and tissue analysis to refine decisions.
For California, this can represent SGMA-related water pressure; for Oregon, use it for irrigation or groundwater constraints. This is not a pumping-allocation calculator. It controls how strongly the engine prioritizes low late-season competition and timely termination.
Pesticide selection, rate, application timing, efficacy and use are outside this calculator and are not evaluated.
The best kill stage depends on species and method. Mechanical termination often improves near flowering/reproductive stages, while mature seed increases volunteer risk and many persistent species can regrow after mowing or grazing.
C:N changes strongly with maturity. Select the actual stage when known; otherwise the calculator uses a broad screening estimate.
Perennials are allowed in one-season mixes when they add useful function, but the calculator checks whether the planned termination method and growth stage are likely to prevent regrowth or carryover.
Optional. When entered, the calculator evaluates the actual growing window and uses it in planting-window and residue-maturity screening.
Choose up to three priorities.

Best Fits for This Field

Ranked from the field conditions, intended use, livestock, termination plan and up to three selected priorities. These are starting points, not automatic substitutions.

Add Species

This list is restricted to the approved Weaver Seed working species set. California barley and needlegrass are excluded.

Important: full-stand rates are working defaults, not guarantees. Variety, seed size, planting date, seedbed, irrigation and field conditions can justify an override.

Mix Composition

Stand equivalents 0%
Calculated rate 0 lb/ac
Total seed 0 lb
Packages —
Species 0
Optional review handoff

Share the formulation with Weaver

Copy the field context, effective seeded acres, component rates, total pounds, major risks and closest standard-mix match. “Email Weaver for Review” opens your email application; the calculator itself does not submit or store the result.

Mix Performance Dashboard

Functional coverage is based on stand-equivalent contribution, not finished bag-weight percentage. Seed pounds and bag percentages are calculated separately.

Agronomic Intelligence

Functional diversity
0
Seed-size compatibility
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Termination risk
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Water competition
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Planting window
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Residue / C:N behavior
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Seed requirement confidence
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Agronomic readiness
0

Optimization Suggestions

Weaver Seed Standard Mix Check

Functional similarity only — a high score does not mean the formulas are compositionally equivalent.

Scenario Comparison

Mix Performance
Agronomic Warnings
Planting Window & Readiness
Physical Compatibility & Risk
Optimization Suggestions
Weaver Seed Standard Mix Match

Saved Mixes

Methodology & Use

This calculator is an agronomic planning and screening tool built from Weaver Seed product knowledge plus published California, Oregon and Western agronomy from sources such as USDA-NRCS, UC Agriculture and Natural Resources, Oregon State University Extension, SARE, Western Extension, NOAA/NCEI and other crop-specific references. Source information is translated into Weaver's own screening logic; references do not imply endorsement of Weaver Seed or of a specific mix.

Use results as a starting point, not a prescription.
Field performance depends on weather, irrigation, soils, pest and disease pressure, crop stage, variety, seed lot, planting equipment, termination timing and management. The calculator does not provide pesticide recommendations or evaluate pesticide selection, rate, application timing, efficacy or use. It also does not replace fertilizer planning based on tissue/soil analysis, veterinary guidance, or site-specific advice from a PCA, CCA, crop adviser or other qualified professional when those decisions are material.
This calculator does not automatically submit results to Weaver.
Calculator results and saved mixes are not automatically sent to Weaver. Saved mixes are stored only in this browser. Optional location coordinates are rounded to about 0.001° before lookup, are not saved with mixes or included in review summaries, and are requested with browser caching disabled where supported. Location analysis sends the rounded coordinates directly from your browser to NOAA/NCEI and SoilGrids to return screening data. Choosing “Email Weaver for Review” opens your email application and sends information only if you choose to send the message.

Soil property estimates: SoilGrids / ISRIC – World Soil Information, CC BY 4.0. Climate screening: NOAA/NCEI observed station data. Modeled and station-derived values should be verified where field-specific accuracy is important.

Mix Rate 0 lb/ac
Total Seed 0 lb