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A Forager’s Year

No. 109

Common evening primrose

Oenothera biennis (also O. parviflora)

king’s cure-all; also small-flowered evening primrose

Flowers, buds & pollen fresh flowers

Drawing: Britton & Brown, Illustrated Flora (1913)

Find
Common in the right habitat
Effort
Grab & eat
ID risk
Beginner
Origin
native
Uses
  • Eat raw / salad

Season

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec

in season peak

Picking: No park we checked allows it. Anywhere else, ask whoever owns or runs the land. See Where you may pick.

What these mean

Find

1 Everywhere · 2 Common in the right habitat · 3 Patchy · 4 Elusive. This is about how much there is, not whether you may pick it. It is based on iNaturalist sightings within 25 km (about 15 miles) of downtown DC, counted on October 3, 2026. The four rules that each plant’s “Find” reason refers to: (A) the estimate is the confirmed sightings, plus the unconfirmed ones (scaled down where the plant has lookalikes in its genus), plus the sightings marked as planted; (B) the tier by estimate: 1,500 or more is tier 1, 250–1,499 tier 2, 50–249 tier 3, under 50 tier 4; (C) tier 1, Everywhere, also needs a source saying the plant is common in lawns, sidewalks, yards or gardens, vacant lots or towns, or at least one DC street tree of it per km of sidewalk, otherwise it is tier 2; (D) if a reliable source says the plant is rare in this region, or that wild plants rarely bear the harvest, only planted sightings count. iNaturalist is a website and phone app where people post photos of the plants and animals they see. A sighting is “research grade” when other users have confirmed what it is; “needs ID” sightings are not confirmed yet, and “cultivated” ones are marked as planted.

Effort

1 Grab & eat · 2 Quick kitchen prep (under about 30 minutes) · 3 Real work (hours, or cooking needed for safety) · 4 Project (days or equipment). Scored on the simplest worthwhile use; each plant’s page says why.

ID risk

How hard it is to harvest safely. Beginner: no dangerous lookalike, and the edible part is not easily confused with a toxic part. Careful: a toxic lookalike, or toxic parts that end up in the harvest unless removed (for example elderberry stems, unripe ground cherries), or other parts of the plant rated medium-or-higher toxicity, with reliable features to separate them. Expert only: a potentially deadly lookalike that is hard to separate, or (for not-recommended harvests like pokeweed) a plant whose safe preparation can’t be guaranteed. Toxic parts that are obviously separate and thrown away anyway (pits, seeds, skins) don’t raise it; the Toxic parts mark carries that warning.

Native or not, and the invader stars

Origin is where the plant comes from: native, non-native, or mixed (the harvest covers both). The stars rate plants on invasive plant lists: ★★★ Virginia DCR “High” or Maryland prohibited invasive · ★★ Virginia “Medium” · ★ Virginia “Low” · ☆ listed only by the Maryland Invasive Species Council or the Mid-Atlantic Plant Invaders guide (advisory) · no stars: native or not listed.

Seasons

Start, peak and end are given in thirds of a month: early, mid or late. A plant counts as in season for a month if it is in season at any point in that month. Some greens and roots have a second window, in spring or fall; their page shows each window. A season that runs across New Year is shown as one window.

What it looks like

The flowers of common evening primrose, a native biennial that grows a flat rosette of leaves in its first year and a hairy, reddish-green flower stalk 3 to 5 feet tall in its second (NC State). The flowers are 1 to 2 inches across, with four pale lemon-yellow petals and a cross-shaped stigma in the center (NC State), and they are lemon-scented (Lady Bird Johnson Wildflower Center). They open in the evening and close by noon the next day (Lady Bird Johnson Wildflower Center), with new flowers opening up the stalk through the season (Ohio State). Edible Wild Food says they taste great and a little sweet, and Eat The Weeds calls them sweet.

Safety

No toxicity is reported for common evening primrose (Ohio State; NC State). Eat The Weeds, a foraging site, says all parts can bother the throat of some people even when cooked and advises trying them carefully and sparingly; no safety source confirms this, and the University of Minnesota advises trying any new edible flower in small amounts at first. The lookalikes named are harmless: common mullein also has tall spikes of small yellow flowers (Practical Self Reliance), but evening primrose flowers have four petals and a cross-shaped stigma (NC State) and mullein’s leaves are densely woolly (NC State); sundrops is a shorter relative that grows as a cluster of stems and flowers by day (Practical Self Reliance; NC State). Do not eat flowers picked from the roadside (University of Minnesota), and avoid lawns, roadsides and park edges that may be sprayed with herbicide.

Lookalikes

Safety flags

Safety marks and flags: what this means

Deadly lookalike / Toxic lookalike: a cited source names a lookalike of that danger, recorded near DC (an iNaturalist sighting within 25 km, a DC street tree, or a Smithsonian listing for DC) and looking like the part you eat. Other lookalikes are still listed, marked “not recorded near DC” or as not looking like the part you eat. Deadly means a source says eating it may be fatal or calls it deadly, or NC State rates it high severity with life-threatening symptoms (sources sometimes disagree; for example Virginia creeper). Each plant’s Lookalikes list says how to tell them apart; “harmless (may be edible)” lookalikes are listed so you know a mix-up isn’t dangerous. Cook first: cooking is needed for safety (for daylilies it is a precaution, not a sourced requirement). Eat in moderation: a source says to limit quantity or frequency (for example oxalates in sorrels and dock, ginkgotoxin, safrole). Spray risk: a source says the plant is commonly treated with herbicide in parks or lawns (invasive control, lawn weeds) or, for ginkgo, sprayed to stop fruiting. Contamination: a source says the plant concentrates pollutants. Each plant’s Safety flags list gives the details and sources.

ID risk
Beginner
Why
No toxic lookalike is named. Common mullein also has tall spikes of yellow flowers (Practical Self Reliance) and sundrops is a shorter, day-flowering relative (Practical Self Reliance; NC State), both harmless; evening primrose has four-petaled flowers with a cross-shaped stigma that open in the evening (NC State; Lady Bird Johnson Wildflower Center), and mullein’s leaves are densely woolly (NC State).
Soil risk
moderate
ID risk: what this means

How hard it is to harvest safely. Beginner: no dangerous lookalike, and the edible part is not easily confused with a toxic part. Careful: a toxic lookalike, or toxic parts that end up in the harvest unless removed (for example elderberry stems, unripe ground cherries), or other parts of the plant rated medium-or-higher toxicity, with reliable features to separate them. Expert only: a potentially deadly lookalike that is hard to separate, or (for not-recommended harvests like pokeweed) a plant whose safe preparation can’t be guaranteed. Toxic parts that are obviously separate and thrown away anyway (pits, seeds, skins) don’t raise it; the Toxic parts mark carries that warning.

Soil risk: what this means

Based on the part you eat, following the urban-soil lead guidance on the Field safety page: higher for greens, shoots and roots; moderate for flowers; low for fruit, nuts and sap.

Field safety for every outing (poison ivy, ticks, soil, and more)

When to pick

Starts
early Jun
Peak
early Aug–late Aug
Ends
late Oct

NC State gives a June to September bloom, and USDA says the plant flowers from June through October. Each flower opens in the evening and closes by the next noon (Lady Bird Johnson Wildflower Center), and new flowers keep opening up the stalk until about September (Ohio State). In the DC area, iNaturalist sightings of plants in flower run from July to October, most in August and September, with one in November.

How the dates were worked out

Every start, peak and end was re-checked in October 2026. “Sourced” means a source opened during the check states that timing for the DC or Mid-Atlantic area. “Estimated” means no source states it exactly; the reason, the evidence and the source links are under “How the dates were worked out” on each plant’s page. Peaks are often estimated, because few sources name a peak. iNaturalist evidence means research-grade sightings near DC, by month, of the plant at that stage (for example, in fruit). iNaturalist is a website and phone app where people post photos of the plants and animals they see. A sighting is “research grade” when other users have confirmed what it is; “needs ID” sightings are not confirmed yet, and “cultivated” ones are marked as planted.

Season basis: estimated: peak

Start

sourced

Peak

estimated: No source names a best month; August is the middle of the Lady Bird Johnson Wildflower Center’s July to September bloom and the month with the most DC-area flowering and total sightings.

End

sourced

Evidence

start: NC State: 'The stem is topped by a showy summer to fall (June to September) bloom.' USDA NRCS: 'The plant flowers can from June through October.' Ohio State: 'Flowering begins in June.' NC State covers North Carolina, USDA the whole country and Ohio State Ohio; all three start bloom in June. Timing from North Carolina’s Piedmont is accepted for the DC area only with a note like this one. In the DC area iNaturalist has one flower-budding sighting in June and the first flowering-annotated sightings in July, so June flowers may be few. | peak: Lady Bird Johnson Wildflower Center: 'Bloom Time: Jul , Aug , Sep'. iNaturalist, research grade within 25 km of DC, flowering-annotated sightings by month: Jul 4, Aug 9, Sep 8, Oct 5, Nov 1; all sightings by month peak in August (97 of 343). | end: USDA NRCS: 'The plant flowers can from June through October.' Minnesota Wildflowers: 'Bloom season: July - October'. iNaturalist, DC area: 5 flowering-annotated sightings in October and 1 in November. NC State ends bloom in September and Ohio State says 'until about September'; the October end follows USDA and the DC-area sightings, covering the documented range.

Where to look

Sunny fields, meadows, roadsides and other disturbed open ground; logged most at Dyke Marsh, in Rock Creek Park and along Four Mile Run, all places where it may not be picked. No listed park allows picking flowers, so pick on private land with permission, away from roadsides.

Habitats
disturbed ground & waste places, vacant lots, old fields & meadows, woods edges, trailsides & thickets
Habitats: what this means

Listed where the plant’s own sources place it in that habitat. “Disturbed ground & waste places” means a cited source places it on disturbed areas, sites, soil or ground, on waste places or waste ground, on construction or abandoned building sites (old home sites count), on rubble or in strip mines. When the source gives examples of the disturbed places, at least one example must be of that kind. Examples that do not count: natural or forestry disturbance (treefall gaps, fire, windthrow, flood scour, old riverbanks and creeks, clear-cuts); roadsides, railroads and rights-of-way; and abandoned fields, pastures and farmland, which are “Old fields & meadows”. “Vacant lots” only where a source says vacant or empty lots.

Most-logged places

None of the most-logged places allows picking.

No picking here (5 places)
  • Dyke Marsh Wildlife Preserve

    25 sightings · Legal to pick: no · see them on iNaturalist

    Look but don’t pick: GW Memorial Parkway sites (incl. Great Falls VA, Theodore Roosevelt Island, Dyke Marsh) designate nothing for gathering.

  • Rock Creek Park

    14 sightings · Legal to pick: no · see them on iNaturalist

    Look but don’t pick: Rock Creek Park’s compendium bans gathering any fruit, nut, berry, seed or greenery.

  • Four Mile Run stream valley (Arlington/Alexandria)

    12 sightings · Legal to pick: no · see them on iNaturalist

    Look but don’t pick: Arlington County park rules (flora shall not be removed or disturbed) and Alexandria’s permit rule both apply.

  • Huntley Meadows Park

    10 sightings · Legal to pick: no · see them on iNaturalist

    Look but don’t pick: Fairfax County parks ban removing any plant part without written permission.

  • Mount Vernon Trail

    10 sightings · Legal to pick: no · see them on iNaturalist

    Look but don’t pick: GW Memorial Parkway sites (incl. Great Falls VA, Theodore Roosevelt Island, Dyke Marsh) designate nothing for gathering.

Most-logged places: what this means

The places with the most research-grade iNaturalist sightings within 25 km of downtown DC (re-counted in October 2026 over every named place, campuses, condominiums and private grounds included), each marked legal to pick or not. A sighting inside several named places counts once, for the smallest of them, but a sighting inside a National Park Service park never counts for a private, campus or unchecked place. iNaturalist shows where people walk and log plants, not true abundance. Private campuses, condominiums, museums, estates and utility land (Pepco’s power-line land near Sligo Creek) are marked “no” (pick only with the owner’s permission); public university campuses, city parks and other places whose picking rules were not checked (county stormwater land, the U.S. Capitol Grounds, Greenbelt’s North Woods, federal facilities such as the National Zoo) are “unknown”. A place needs at least 2 sightings, so plants with very few sightings have no places. At-risk plants (butternut, nannyberry, American chestnut, ramps, riverbank goldenrod) get places like every other plant; each page says why the plant is at risk and gives any advice its sources give. For some places, mostly Rock Creek Park, the iNaturalist map shows more sightings than the count here, because a map link cannot leave out exactly the sightings credited to another place. iNaturalist is a website and phone app where people post photos of the plants and animals they see. A sighting is “research grade” when other users have confirmed what it is; “needs ID” sightings are not confirmed yet, and “cultivated” ones are marked as planted.

Ways to use it

  • eaten raw in salads (Edible Wild Food; Eat The Weeds; Practical Self Reliance)
  • a garnish (Eat The Weeds; Practical Self Reliance)
  • harvest the flowers just after they close, when Practical Self Reliance finds them sweetest and least spicy

Keeping

Use them the day you pick them.

Use within
pick & use same day
Keeps fresh
Same day; overnight at most in a bag in the fridge (general guidance for edible flowers). University of Minnesota: harvest edible flowers the day you will use them, no more than one day early, and refrigerate them in plastic bags until use. Each evening primrose flower closes by the next noon (Lady Bird Johnson Wildflower Center), so pick open flowers in the evening or early morning.
Keeping basis
general guidance for its type
Canning: what this means

Shelf-stable canning, three levels. Lab-tested: a lab-tested recipe from the National Center for Home Food Preservation (NCHFP) or Oregon State covers this fruit and product, or a generic recipe for its kind (the line says so, for example chokeberry). Extension recipe: a published Extension recipe (University of Alaska Fairbanks, written for Alaska species; University of Maine’s dandelion jelly), or a process that is safe only with a pH meter; follow it exactly, never improvise. No tested recipe: refrigerate or freeze, don’t can. “Hot-bottled syrup” = maple and walnut syrup, which keep when bottled hot at full syrup density. The Canning line names the exact product each source covers, for example “whole berries” or “juice”; a product not named there (such as juice from a berry with only a whole-berry recipe) has no tested recipe.

Keeping basis: what this means

“Specific to this plant” or “general guidance for its type” (for example NCHFP guidance for leafy greens applied to a wild green).

Nutrition

Not researched: in October 2026, only the calendar’s plants of the month and chicory leaves were researched.

Native or not

Origin
native
Native range
eastern and central North America (per NC State)
Virginia invasive rank
not listed
Maryland invasive status
not listed
Native or not, and the invader stars: what this means

Origin is where the plant comes from: native, non-native, or mixed (the harvest covers both). The stars rate plants on invasive plant lists: ★★★ Virginia DCR “High” or Maryland prohibited invasive · ★★ Virginia “Medium” · ★ Virginia “Low” · ☆ listed only by the Maryland Invasive Species Council or the Mid-Atlantic Plant Invaders guide (advisory) · no stars: native or not listed.

Virginia DCR, Virginia Invasive Plant Species List (effective September 2024), verbatim: "Under the DCR Invasive Species Assessment Protocol, approved by the Virginia Invasive Species Working Group, January 2024, species were ranked as exhibiting high, medium or low levels of invasiveness based on their threat to natural communities and native species. Invasiveness rank is higher for species that: • Alter ecosystem processes, such as succession, hydrology or fire regime. • Are capable of invading undisturbed natural communities. • Cause substantial impacts on rare or vulnerable species or natural communities or high-quality examples of more common communities. • Are found widely distributed and generally abundant where present. • Disperse readily to new areas. • Are difficult to control." The list also states: "The list is for educational purposes only and has no regulatory authority."

Maryland Department of Agriculture, Maryland Prohibited Invasive Plant Law and Regulations page, verbatim: "Plants on the Maryland Prohibited Invasive Plant List may not be added to stock after the effective date and should not be sold after their phase-out period ends."

No official DC invasive plant list was found.

How the ratings were set

Find
Common in the right habitat Estimate 795 = 343 research-grade iNaturalist sightings within 25 km + 717 needs-ID sightings counted at 57% (343 of the 603 research-grade Oenothera sightings here are common evening primrose and its close relatives in Oenothera subsection Oenothera) + 44 'cultivated' (planted) sightings (rule A); that is tier 2 by count (rule B). Rule D does not apply: the Digital Atlas of the Virginia Flora says small-flowered evening-primrose is "Frequent in the mountains, apparenty rare elsewhere.", but that is 9 of the 343 research-grade sightings here, not the harvest as a whole, and the same atlas says the members of the common evening-primrose complex "are common inhabitants of fields, pastures, roadsides, clearings, and other open, disturbed habitats throughout the state". Final tier 2.
Effort
Grab & eat Pick the open flowers in the evening or early morning and eat them raw in salads or as a garnish.
Find: what this means

1 Everywhere · 2 Common in the right habitat · 3 Patchy · 4 Elusive. This is about how much there is, not whether you may pick it. It is based on iNaturalist sightings within 25 km (about 15 miles) of downtown DC, counted on October 3, 2026. The four rules that each plant’s “Find” reason refers to: (A) the estimate is the confirmed sightings, plus the unconfirmed ones (scaled down where the plant has lookalikes in its genus), plus the sightings marked as planted; (B) the tier by estimate: 1,500 or more is tier 1, 250–1,499 tier 2, 50–249 tier 3, under 50 tier 4; (C) tier 1, Everywhere, also needs a source saying the plant is common in lawns, sidewalks, yards or gardens, vacant lots or towns, or at least one DC street tree of it per km of sidewalk, otherwise it is tier 2; (D) if a reliable source says the plant is rare in this region, or that wild plants rarely bear the harvest, only planted sightings count. iNaturalist is a website and phone app where people post photos of the plants and animals they see. A sighting is “research grade” when other users have confirmed what it is; “needs ID” sightings are not confirmed yet, and “cultivated” ones are marked as planted.

Effort: what this means

1 Grab & eat · 2 Quick kitchen prep (under about 30 minutes) · 3 Real work (hours, or cooking needed for safety) · 4 Project (days or equipment). Scored on the simplest worthwhile use; each plant’s page says why.

Sources

25 sources, each linked to the original.

  1. Rock Creek Park Superintendent’s Compendium National Park ServiceBacks up: picking rules
  2. 36 CFR 2.1 - Preservation of natural, cultural and archeological resources Legal Information Institute, Cornell Law School (text of federal regulation)Backs up: picking rules
  3. Common Evening-primrose (Oenothera biennis), Ohio Perennial and Biennial Weed Guide Ohio State University, College of Food, Agricultural, and Environmental SciencesBacks up: description, habitat, season, safety, effort & ID risk, safety details
  4. Oenothera biennis (Common Evening Primrose) NC State Extension Gardener Plant ToolboxBacks up: description, habitat, season, safety, native or invasive status
  5. Oenothera biennis (Common evening-primrose) Lady Bird Johnson Wildflower CenterBacks up: description, season, safety, keeping
  6. Evening Primrose Edible Wild FoodBacks up: description, uses, habitat
  7. Evening Primrose, Oenothera biennis: Foraging Standby (Green Deane) Eat The WeedsBacks up: description, uses, safety
  8. Oenothera parviflora L. (Small-flowered Evening-primrose) (Digital Atlas of the Virginia Flora) Virginia Botanical Associates (Digital Atlas of the Virginia Flora)Backs up: findability
  9. iNaturalist research-grade observations of Oenothera subsection Oenothera (common evening primrose complex) within 25 km of downtown DC iNaturalistBacks up: findability
  10. Common Evening Primrose (Oenothera biennis) (J. Hilty) Illinois WildflowersBacks up: habitat
  11. Annotated Checklist of the Vascular Plants of the Washington-Baltimore Area, Part I (Shetler & Orli, 2000) Smithsonian Institution, National Museum of Natural History, Department of BotanyBacks up: habitat
  12. Oenothera biennis L. (Common Evening-primrose) (Digital Atlas of the Virginia Flora) Virginia Botanical Associates (Digital Atlas of the Virginia Flora)Backs up: habitat, findability
  13. USDA PLANTS Database: Oenothera biennis (OEBI), native status USDA NRCSBacks up: native or invasive status
  14. Virginia Invasive Plant Species List (effective date: September 2024) Virginia Department of Conservation and Recreation, Division of Natural HeritageBacks up: native or invasive status
  15. Maryland Prohibited Invasive Plant Law and Regulations (Maryland Prohibited Invasive Plant List, updated January 2026; additions effective July 15, 2026; 'Next Plants To Be Assessed' 2026-2027) Maryland Department of Agriculture, Plant Protection & Weed ManagementBacks up: native or invasive status
  16. Non-Native Invasive Terrestrial Plant Species in the State of Maryland (updates approved through the April 18, 2024 MISC meeting) Maryland Invasive Species CouncilBacks up: native or invasive status
  17. Plant Invaders of Mid-Atlantic Natural Areas, Field Guide (Swearingen & Fulton, 2022; successor to the NPS/USFWS 5th ed., 2017) Mid-Atlantic Invasive Plant Council / Passiflora Press (hosted by Bugwood/Mid-Atlantic Invaders Tool)Backs up: native or invasive status
  18. Invasive Plants in the District DC Department of Energy & EnvironmentBacks up: native or invasive status
  19. Edible flowers University of Minnesota ExtensionBacks up: safety, storage, keeping
  20. Verbascum thapsus (Common Mullein) NC State Extension Gardener Plant ToolboxBacks up: safety, effort & ID risk, safety details
  21. Oenothera fruticosa (Sundrops) NC State Extension Gardener Plant ToolboxBacks up: safety, effort & ID risk, safety details
  22. iNaturalist research-grade observations of Oenothera subsection Oenothera within 25 km of Washington, DC, by month (flowering) iNaturalistBacks up: season
  23. Plant Guide: Common Evening-primrose, Oenothera biennis (Immel, 2001) USDA NRCS National Plant Data CenterBacks up: season, habitat
  24. Common Evening Primrose (Oenothera biennis) Minnesota WildflowersBacks up: season, safety, safety details
  25. Identifying Evening Primrose (& Ways to Use It) Practical Self RelianceBacks up: uses, safety, effort & ID risk, safety details