Field Pennycress (Thlaspi arvense) Seeds – Extremely Cold-Hardy Winter Cover Crop, Oilseed Biofuel Crop, Erosion Control & Soil Builder

Minimum: 50+ Seeds

The Cover Crop That Grows When Nothing Else Will

Most cover crops go dormant or die back once real winter cold sets in. Field Pennycress keeps growing. This extraordinarily cold-hardy winter annual germinates in fall, survives temperatures that kill nearly every other cover crop, and resumes growth the moment the ground thaws, producing a dense root mat that holds soil through the harshest months. Its small oilseed pods have also drawn interest as a biofuel feedstock, giving this once-overlooked mustard relative a genuine second life as an agricultural crop. This is a working plant for growers who need real winter cover, not a fair-weather cover crop.

Who Plants Field Pennycress?
The farmer or gardener needing winter erosion control on exposed ground.
The cover crop user wanting a species that survives extreme cold better than most.
The soil health grower interested in a fast fall and winter living cover.
The biofuel-curious grower exploring pennycress as an emerging oilseed crop.

What This Cold-Hardy Oilseed Crop Actually Is
Thlaspi arvense, called field pennycress or stinkweed, is a winter annual in the mustard family, native to Europe and Asia and naturalized across North America as a common weed, now grown for cover crop and oilseed value. Plants form a low rosette in fall, overwinter near-dormant under snow and ice, then bolt rapidly in spring into a branching stem topped with small white flowers and flat, round seed pods. Those pods contain small oilseeds with an oil profile drawing commercial interest as a biodiesel feedstock, grown as a cash cover crop between summer row crops. Its extensive roots and rapid fall establishment make it effective for winter erosion control. Grown as a winter annual across a wide hardiness range, reliably surviving winters that kill less cold-tolerant cover crops.

In the Field & Garden

• Winter erosion control: Sow in fall to establish cover before winter, holding soil on slopes.
• Cash cover crop rotation: Plant between summer crops to build soil and produce oilseed.
• Biofuel feedstock trial: Grow as an entry point into pennycress's role as a biodiesel crop.
• Early pollinator support: Let plants bolt and flower in early spring for one of the first nectar sources.
• Soil building: Use as a fall-sown green manure, incorporating residue before spring planting.
• Extreme cold-climate cover: Choose where other winter covers fail to survive hard freezes.

Growing Field Pennycress Seeds

• Start method: Direct sow outdoors; no transplanting.
• Timing: Sow late summer to early fall for winter cover, before first hard frost.
• Germination: Sprouts in 7-14 days in cool fall soil.
• Soil temperature: Germinates well in cool soil many cover crops can't tolerate.
• Seeding rate: Broadcast at a rate suited to plot size; denser stands improve erosion control.
• Sunlight: Full sun to part shade.
• Soil: Tolerates a wide range of soils, including poor or compacted ground.
• Watering: Minimal supplemental watering needed once established.
• Winter survival: Overwinters as a low rosette, resuming growth and bolting rapidly in spring.
• Life cycle: True winter annual, from fall germination to spring seed set.
• Harvest, oilseed: If harvesting seed, cut once pods mature and dry in late spring before shattering.
• Hardiness: Exceptionally cold-tolerant; among the most winter-hardy cover crops available.

Before You Close This Page
This is the cover crop built for the coldest months, not just the mild ones. Field Pennycress germinates in fall, survives winters that kill other cover crops outright, and resumes growth the instant the ground thaws. Its dense roots hold soil through winter, and its oilseed pods make it a genuine biofuel candidate too. Sow it where erosion control matters and other winter covers have failed. Grow the plant that keeps working after everything else has gone dormant.