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Crimson Clover
Photo: "crimson clover" by Oregon State University · CC BY-SA 2.0

Crimson Clover

Annual · Fabaceae

Crimson clover is a cool-season legume cover crop used for nitrogen contribution, soil cover, erosion reduction, and pollinator bloom. It should be inoculated where needed, sown in the correct fall or cool-season window, and terminated before seed set unless reseeding is intentional. It is a winter annual. Key facts: 60–90 days to maturity from direct_sow, 6+ hours of sun. Not recommended for containers.

Updated June 1, 2026 · Backed by 4 cited sources
Overview

At a Glance

The essentials first: timing, light, spacing, seed-starting, container fit, and overall size.

Days to maturity
60–90 days
from direct_sow
Sun
6+ hours
Container
No
Height
1–1.5 ft
at maturity
Planting window

Zone Planting Guide

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Season sequence

Crimson Clover Cover Crop Cycle

Sowing through termination, in the order the work happens.

  1. 1
    Late summer
    Sow crimson clover after harvesting summer vegetables (6-8 weeks before first frost).
  2. 2
    Fall
    Establishing, no action needed until spring.
  3. 3
    Early spring
    Terminate at bud/early bloom, mow or till under.
  4. 4
    Spring +2-3 weeks
    Residue decomposing, safe to plant seeds now.
Common questions

Crimson Clover FAQ

Every answer is assembled from this cultivar's own record, so the figures match the rest of the page.

How many days to maturity for Crimson Clover?

Crimson Clover takes 60–90 days to reach maturity from direct sowing.

How much sun do Crimson Clover need?

Crimson Clover needs at least 6 hours of direct sun a day.

How much water do Crimson Clover need?

Crimson Clover needs 1 inches of water a week, counting rainfall.

What soil pH do Crimson Clover need?

Crimson Clover grows best in soil with a pH of 5.5–7.

How tall do Crimson Clover get?

Crimson Clover reaches 1–1.5 feet at maturity.

How do you start Crimson Clover from seed?

Sow seed straight into the garden.

What temperature do Crimson Clover seeds need to germinate?

Crimson Clover seeds germinate best at 50°F, and take 7–14 days to emerge.

Can you grow Crimson Clover in containers?

Crimson Clover is not recommended for container growing.

When is Crimson Clover in season?

Crimson Clover is a cool-season crop, in season during spring and fall in most regions. Plants reach harvest 60–90 days after direct sowing and prefer temperatures below 75°F.

Resilience

Plant Health

Stress tolerance, resistance notes, and the most common problems to watch for as plants mature.

Tolerance
Heat: Medium Cold: Medium Drought: Medium

Watch for these first

Sort
Issue Severity Category Peak window
Crown rot Sclerotinia trifoliorum
High Disease Apr, May, Jun, Sep, Oct Peak window months: Apr, May, Jun, Sep, Oct.

Sclerotinia crown and stem rot on clovers, alfalfa, vetches, and related forage legumes. A cool, wet-season disease that can kill seedlings or wipe out patches after fall establishment, wet winters, or prolonged snow cover.

Triggers: Cool moist weather, fall seeding, wet soils, dense canopy, poor air circulation, and prolonged snow cover all favor disease.

Risk fades when: Drier conditions reduce active infection pressure, though stand damage may already be visible by spring.

Damping off Pythium spp. / Rhizoctonia solani / Fusarium spp.
High Disease May–Aug Peak window months: May, Jun, Jul, Aug.

A seedling killer caused by several different fungi working together. It hits vegetables, flowers, herbs, microgreens, and cover-crop seedlings the same way — seeds rot before they emerge, or young seedlings collapse right at the soil line. Wet seed-starting mix and poor airflow in seedling trays are the classic conditions.

Triggers: Wet soil or starting mix, poor drainage, seedlings packed too tightly, contaminated trays or media, and stagnant air all favor damping-off.

Risk fades when: Drying the soil surface and improving airflow slows new spread. Collapsed seedlings don't recover, but the rest of the tray can be saved.

Damping off symptoms
Damping off of coffee seedlings caused by Fusarium sp. — Photo: Scot Nelson · CC0 1.0
Common leaf spot (clover & alfalfa) Pseudopeziza medicaginis, Pseudopeziza trifolii
Moderate Disease May–Sep Peak window months: May, Jun, Jul, Aug, Sep.

The most common leaf disease of alfalfa and clover cover crops. It makes small, dark brown to black circular spots with slightly fringed edges, often with a tiny raised fruiting disk in the center. Spots start on the lower leaves and move up, and infected leaves yellow and drop, thinning the stand. It is favored by cool, moist weather and is worst in spring and fall.

Triggers: The fungus overwinters in leaf debris and spreads by spores during cool, moist weather. Dry, warm summer weather slows it; cool, moist fall conditions favor a resurgence. A dense canopy that traps humidity raises risk.

Risk fades when: Dry, warm weather slows it. Two days above 82°F or three dry days exits the active window; spotted leaves stay damaged.

Rust (clover & alfalfa) Uromyces striatus, Uromyces trifolii
Moderate Disease May–Aug Peak window months: May, Jun, Jul, Aug.

A rust of alfalfa and clover cover crops that makes small reddish-brown pustules on both leaf surfaces and sometimes on stems. The pustules rupture and release powdery spores, and heavy infection yellows and drops leaves, weakening the stand. It is favored by humid weather and extended leaf wetness.

Triggers: Favored by humidity and extended leaf wetness. Reddish-brown pustules on both leaf surfaces release powdery spores spread by wind. Often associated with nearby spurge as an alternate host.

Risk fades when: Hot or dry weather slows rust. Two days above 88°F or three dry days exits the active window; existing pustules remain.

Feeding & picking

Nutrition & Harvest

How hungry the plant is, what ripe harvest looks like, and how long the crop keeps after picking.

Feeding
Nutrition
Feeding intensityLight feeder
Timing
Harvest
  • Early bloom to mid-bloom
Plant relationships

Companion Planting

Helpful neighbors can support growth or deter pests. Keep antagonistic plants separated to reduce stress and competition.

Good companions
Silver Queen Sweet Corn
Crimson clover can provide spring nitrogen for full-season corn.
Better Boy Tomato
Crimson clover mixes can provide fertility-enhancing mulch for tomato transplants.
Clover Cover Crop
Mixed clovers can extend soil cover and diversify nitrogen-building cover crops.
What it does3
Soil building Research supported
Medium red clover is a short-lived perennial or biennial legume used as an nitrogen source, soil builder, and forage/green-manure cover crop.
SARE red clover
Weed control Research supported
Helps suppress weeds when frostseeded or interseeded with small grains and maintained as a dense stand.
SARE red clover
Beneficial insects Research supported
SARE lists red clover as an beneficial-insect crop in addition to its nitrogen and soil-building roles.
SARE red clover
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What you'll need

Growing Supplies

Hand-picked for your Crimson Clover, with the extension research behind every recommendation.

Mulch / landscape fabric

Nearly every garden benefits from mulch for weed suppression, moisture conservation, and soil temperature moderation. For most home gardeners, quality organic mulch is the better buy over landscape fabric.

Source: Penn State Extension; Wisconsin Horticulture; Illinois Extension

Our pick

Cleaned Wheat Straw Mulch (3 cu ft, ~20 lbs)

Thoroughly cleaned wheat straw at 3 cubic feet, marketed specifically for vegetable gardens rather than animal bedding or decoration. Better per-pound economics than the 1 cu ft option, with the same extension-recommended material. Strong sales volume (2K+ bought past month) supports product consistency.

paid link ?When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research. When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research.
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Drip irrigation / soaker hose kit

Every gardener benefits from putting water at the root zone instead of on the leaves, because drip and soaker systems reduce foliar disease pressure by limiting leaf wetness and soil splash. A quality kit should include a backflow preventer, filter, pressure reducer, and UV-resistant tubing.

Source: Iowa State University Extension; Colorado State University Extension; UMass Extension

Our pick

Complete Garden Drip Irrigation Kit

Designed for beginners with a step-by-step setup guide. Adjustable emitters, both tubing sizes, and all connectors included.

paid link ?When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research. When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research.
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Row cover / frost blanket

Row cover adds frost protection, speeds early growth, and physically excludes insect pests without spraying. Look for spun-bonded fabric with a stated weight and frost rating, UV resistance, and enough width for hoops or low tunnels.

Source: University of Maryland Extension; University of New Hampshire Extension; Colorado State University Extension

Our pick

Frost Blanket (10'x30')

Thicker 1.2 oz fabric rated to protect down to 28°F. Covers 300 sq ft — enough for multiple raised beds in a single sheet.

paid link ?When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research. When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research.
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Garden shade cloth

K-State Research and Extension and University of Maryland Extension recommend shade cloth as a heat-management tool for vegetable gardens, with 30 percent shade rating most effective for tomatoes, peppers, and fruiting crops, and 40 to 50 percent for protecting heat-sensitive greens during hot summer months. University of Delaware research found 30 percent black shade cloth tripled marketable yield for bell peppers compared to unshaded plants, and Purdue trials showed shade cloth reduced maximum daily temperatures by 8 to 10 degrees Fahrenheit. Choose knitted polyethylene with reinforced grommets every 18 to 24 inches, mount on hoops or a frame with open sides for airflow, and remove or vent during prolonged wet weather to avoid increased humidity in the canopy.

Source: K-State Research and Extension; University of Maryland Extension; University of Delaware Cooperative Extension; Purdue University Extension

Our pick

30% Sun-Block Shade Cloth (6x10 ft)

Same 30 percent rating in the typical home-garden size that fits a 4 by 8 raised bed plus working overhang. Knitted polyethylene with grommets for tie-down. Strong volume signal (3.8K reviews) supports consistent product quality across orders.

paid link ?When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research. When you shop on Amazon using this link, SoilStack earns a small commission at no extra cost to you. It's how we keep the site free and the calendar ad-free. Every product on this page was hand-selected based on university extension research.
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Research

Sources

Reference material and extension guidance used to build this growing guide.

reference SARE, Managing Cover Crops Profitably: Crimson Clovergovernment USDA ARS, Crimson Clover cover crop factsheet (nitrogen fixation)peer-reviewed SARE, Sustainable Agriculture Research and Educationuniversity Illinois Extension - Caring for Annuals
Internal links

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