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Cereal rye

Secale cereale · grasses

At a glance

Light
Full sun
Frost
Hardy (estimate)
Days to maturity
90–120 (estimate)
Lifespan
Annual
On this page

Also called winter rye.

No photo of this plant yet. We add one once we have a picture we can credit.

When do I plant this? › Plan this in your garden ›

The numbers

Mature height
0.6–1.2 m2–4 ft
Mature spread
15–30 cm6–12 in
Days to maturity
90–120 (estimate)
Light
Full sun
Feeding
Light feeder (estimate)
Root depth
Deep (estimate)
Frost tolerance
Hardy (estimate)
Lifespan
Annual
Habit
One upright stem
Value to pollinators
Low (estimate)

USDA PLANTS profile

Numbers we’re less sure of

Many of our estimates come from an extension page we’ve read that gets close without pinning the number down. Others are still our own best guess, and on some the sources disagree. Treat them all as a starting point.

Rules that apply to cereal rye

Ground that just carried cereal rye or a sorghum cover crop is a poor seedbed for small seeds for a few weeks. As the residue breaks down it releases chemicals that stop small seeds germinating, and the smaller the seed the worse it fares; transplants and big seeds largely shrug it off. Promising

Ground that just carried cereal rye or a sorghum cover crop is a poor seedbed for small seeds for a few weeks. As the residue breaks down it releases chemicals that stop small seeds germinating, and the smaller the seed the worse it fares; transplants and big seeds largely shrug it off.

Promising

If you skip this, it still grows, just less well. The planner suggests it.

How it works: Rye and sorghum roots and residue release allelochemicals (benzoxazinoids from rye, sorgoleone from sorghum) that persist in the surface soil for weeks after the cover is killed. A small seed sown into that layer has little reserve to push through the inhibition; a large seed or a transplant is already past the germination window.

Evidence: checked against 4 sources in the research-based literature.

The 4 sources

crops.extension.iastate.edu

Cereal Rye Cover Crops, Allelopathy and Corn Iowa State Univ. Extension, Integrated Crop Management
Research has shown that susceptibility to allelochemicals is indirectly related to seed size - the smaller the seed the more susceptible the plant

content.ces.ncsu.edu

Weed Management on Organic Farms NC State Extension
Small-seeded and slow germinating crops are more likely to be adversely effected by allelopathic cover crops than are large-seeded, rapidly germinating crops (Weston, 1996)

fieldreport.caes.uga.edu

Organic Cool-Season Vegetable Crop Rotations for the Southeast Univ. of Georgia Cooperative Extension, Bulletin 1498
A direct-seeded crop with small seeds is particularly vulnerable to allelopathic chemicals

extension.illinois.edu

Cereal rye/winter rye: the perfect garden-reset cover crop Univ. of Illinois Extension
It needs to be terminated in mid to late spring before it goes to seed, about 2 weeks before the desired transplant date.
Remedy

Wait about two weeks after killing rye and about four after sorghum before sowing small seeds, water an inch to leach the surface, or plant transplants. Big seeds and transplants can go in sooner.

Read the full rule › · open in the planner ›

Cold-hardy annuals can be sown or transplanted before the last spring frost (hardy crops about three weeks before, half-hardy about two weeks before). Tender crops wait for the frost itself. Promising

Cold-hardy annuals can be sown or transplanted before the last spring frost (hardy crops about three weeks before, half-hardy about two weeks before). Tender crops wait for the frost itself.

Promising

If you skip this, it still grows, just less well. The planner suggests it.

How it works: Cold hardiness. Hardy crops tolerate hard frost and half-hardy crops tolerate light frost, so they can occupy the ground weeks before frost-tender crops are allowed in. The offset is measured from the last spring frost.

Evidence: checked against 2 sources in the research-based literature.

The 2 sources

extension.illinois.edu

Time Your Vegetable Plantings by Cold Hardiness University of Illinois Extension
… withstand freezing temperatures and hard frosts without injury

extension.colostate.edu

Vegetable Planting Guide Colorado State Univ. Extension, GardenNotes #720
As early as 2-4 weeks before the date of the average last spring frost

Plus 2 working notes on how the sources were read.

Read the full rule › · open in the planner ›

A winter cover crop is sown in autumn a set time before the first fall frost (about six to eight weeks for crimson clover, 30 to 45 days for hairy vetch, four to six weeks for cereal rye), so it roots and grows before winter. Promising

A winter cover crop is sown in autumn a set time before the first fall frost (about six to eight weeks for crimson clover, 30 to 45 days for hairy vetch, four to six weeks for cereal rye), so it roots and grows before winter.

Promising

If you skip this, it still grows, just less well. The planner suggests it.

How it works: The plants need time to germinate and grow before the first hard frost and short days force them into dormancy; sown too late, a cover crop neither covers the soil through winter nor survives to grow again in spring. Sown too early, crimson clover can go to seed in the fall and not regrow until the soil warms. Cereal rye tolerates the latest sowing of the three.

Evidence: checked against 6 sources in the research-based literature.

The 6 sources

extension.umd.edu

Cover Crops For Gardens University of Maryland Extension
Fall-sown cover crops are typically planted in a two-month window, starting in mid-August and ending no later than mid-October. The plants should have enough time to germinate and grow before the first hard frost and short days force them into dormancy.

sare.org

Managing Cover Crops Profitably USDA SARE
Seed six to eight weeks before the average date of first frost

sare.org

Managing Cover Crops Profitably USDA SARE
Plant vetch 30 to 45 days before killing frost for winter annual management

hgic.clemson.edu

Cover Crops for the Fall Clemson Cooperative Extension HGIC
Legumes should be planted 6 to 8 weeks before a killing frost, and non-legumes should be planted 4 to 6 weeks before a killing frost.

Managing Cover Crops Profitably USDA SARE
In many regions, seed winter covers at least six weeks before a hard frost. Winter cereals, especially rye, are an exception and can be planted a little later. If ground cover and N recycling needs are minimal, rye can be planted as late as the frost period for successful overwintering.

www.uvm.edu

Optimize Your Cereal Rye Cover Crop with the Right Sowing Dates and Seeding Rates University of Vermont Extension, NW Crops & Soils
… the optimal window for sowing cereal rye is during the four-week window around the historic first frost date for that location.
Remedy

Sow within the crop's window before your typical first fall freeze: crimson clover six to eight weeks before it, hairy vetch 30 to 45 days before, cereal rye four to six weeks before (rye can go in later and still overwinter, with less growth before winter).

Read the full rule › · open in the planner ›

Frost can form on a night the forecast low is a few degrees above freezing. Promising

Frost can form on a night the forecast low is a few degrees above freezing.

Promising

If you skip this, the planting fails. The planner warns you.

How it works: On a clear, still night leaves lose heat to the open sky, so a leaf can fall to freezing and ice can form in it while the thermometer, a couple of meters up, still reads a few degrees above.

Evidence: checked against 7 sources in the research-based literature.

The 7 sources

www.weather.gov

Frost and Freeze Information NWS Tallahassee
Issued up to 24 hours when temperature is forecast to be between 32° and 36° on nights with calm winds

www.weather.gov

Freeze Watches and Warnings National Weather Service
… temperatures below 28°F for an extended period of time can kill most types of commercial crops and residential plants.

ipm.ucanr.edu

Freezing and Frost UC Statewide IPM Program
Frost occurs when air is warmer than 32°F but plant tissues drop to 32°F or below because plants radiate (lose) heat into the atmosphere, especially during cool, clear nights.

yardandgarden.extension.iastate.edu

Fall Planting of Vegetables Iowa State University Yard and Garden, Aaron Steil and Kim Hilgers
Tender crops will be damaged or destroyed by a light frost

extension.sdstate.edu

Fall Frost Tolerance of Common Vegetables SDSU Extension, Rhoda Burrows
Crops from more-temperate regions can withstand light freezes (28 to 32 degrees Fahrenheit):

extension.umn.edu

A Minnesota guide to garden timing UMN Extension, Robin Trott
A light frost (32°F) can damage tender plants, while a hard frost (28°F or colder) will kill most warm-season crops.

extension.colostate.edu

Frost Protection and Extending the Growing Season CSU Extension GardenNotes #722, Whiting, O'Meara and Wilson
Radiation frosts occur on calm clear nights that lack cloud cover to hold in heat.
Remedy

The evening before, cover the crops at risk with a sheet or frost cloth, never plastic, reaching the ground and loose at the bottom so the soil's warmth can rise under it, and take it off in the morning. A cover helps least in a long, hard freeze.

Read the full rule › · open in the planner ›

A cover buys cool-season crops a week or two at the ends of the season. A good hunch

A cover buys cool-season crops a week or two at the ends of the season.

A good hunch

If you skip this, it still grows, just less well. The planner suggests it.

How it works: Soil warmed by the sun by day is the heat source at night; a covering low to the ground traps that heat around the plants on calm, clear nights, keeping them a few degrees above the open air through the light frosts at each end of the season.

Evidence: checked against 6 sources in the research-based literature.

The 6 sources

yardandgarden.extension.iastate.edu

All About Cold Frames Iowa State University Extension and Outreach, Aaron Steil
The ground and frame of the cold frame are heated by the sun during the day and radiate that heat during the night, keeping the inside warmer. They are used to extend the growing season by two to four weeks in both the fall and the spring, allowing you to start plants outdoors earlier and continue growing them later in the season.

extension.colostate.edu

Frost Protection and Extending the Growing Season CSU Extension GardenNotes #722, Whiting, O'Meara and Wilson
In trials in Fort Collins, Colorado, a plastic cover on a frame typically provides 3°F to over 6°F of frost protection. It works well for cool season crops that are somewhat tolerant of frosty nights and adds two to six weeks or more on both ends of the growing season.

class.ucanr.edu

Frost Protection and Extending the Growing Season CSU Extension GardenNotes #722, Whiting, O'Meara and Wilson
Soil warmed by the sun in the daytime, is the source of heat for frost protection at night. Moist, smooth soil absorbs more heat. To trap heat from the soil around young vegetables at night, place a covering that is low to the ground and spreading. To recharge the heat source for the next night, any covering must allow sunlight to shine through to the soil or must be removed in the daytime.

extension.usu.edu

Extending the Garden Season Utah State University Extension, Beddes, Caron, Hansen and Gunnell
Low = Plant 1–2 weeks before suggested planting date; Medium = 2–4 weeks before suggested planting date; High = 4–8 weeks before average planting date

hort.extension.wisc.edu

Floating Row Cover University of Wisconsin-Madison Extension, Wisconsin Horticulture, Susan Mahr
Depending on the weight of the covering you choose, you can gain between 2 and 8 degrees of frost protection or warm the local environment sufficiently to harvest certain crops a week or two early.

uaex.uada.edu

Row covers for vegetable gardening University of Arkansas System Division of Agriculture, Cooperative Extension Service
Clear plastic is useless in providing frost protection because the radiant energy released from the soil on those frosty nights passes right through the covering and never warms the air around the plants.
Remedy

Sow or set out cool-season crops under the cover that many weeks ahead of the open-ground date, and keep autumn crops covered past the usual last call. Vent on sunny days, keep plastic off the leaves, and close the cover before sunset.

Read the full rule › · open in the planner ›

Another 138 rules depend on your own garden, like crop rotation, frost dates, sun, spacing and soil. See them all.

Plant teams that place it

When do I plant cereal rye? ›

What grows well with cereal rye? · Something wrong with your cereal rye?

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Milpa Gardens. “Cereal rye (Secale cereale).” https://milpa.garden/plants/secale-cereale/

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