Hoary cress

Identification & Biology
Alias' : Whitetop, heart-podded hoary cress, pepperweed
Latin Name : Cardaria draba
Category : Terrestrial Plants
Description :
  • Perennial plant that reproduces by seed and rhizomes
  • Grows up to 0.6 m tall
  • White flowers with four petals, giving it a flat-topped appearance
  • Arrowhead-shaped leaves are covered with soft white hairs, giving the foliage a grey-green appearance
  • Lower leaves are stalked, while the upper leaves have 2 lobes clasping the stem


Flowering typically occurs in April and May, but can continue into early summer. Plants set seed by mid-summer. Fortunately, the viability of hoary cress seeds is only about 3 years. Hoary cress may be confused with rosettes of gumweed (Grindelia squarrosa), globe-pod hoary cress (Cardaria pubescens) and perennial pepperweed (Lepidium latifolium).

Look Alikes

In British Columbia, hoary cress grows at low-to-mid-elevations on the coast and in the interior grassland and forest regions, where it is found on dry roadsides, fields and disturbed habitats. It is typically found on open, unshaded, disturbed ground. Hoary cress grows well on alkaline soils that are wet in late spring and does better in areas with moderate amounts of rainfall.

Impact & Risks
  • Hoary cress can be highly competitive with native vegetation on rangeland.
  • It is generally considered unpalatable to livestock and is often spread as a contaminant of alfalfa hay.
Prevention & Mitigation

The most effective way to ensure that your lands do not become infested with hoary cress is by prevention. Here are some recommendations to prevent hoary cress from invading your property:

  • Maintain your crops and natural lands in a healthy, vigorous condition to ensure a competitive plant community; competitive perennial grasses and forbs utilize water and nutrients that would otherwise be readily available to hoary cress.
  • Regularly patrol your property for hoary cress plants and immediately control or remove infestations before seed set. Do not leave plants to compost as they may still produce viable seed.
  • Cooperate with adjacent landowners and encourage them to prevent hoary cress spread.
  • Immediately re-vegetate disturbed, bare soils with a suitable seed mixture that provides dense, early colonization to prevent weed invasion.
  • Do not move contaminated soils to a new area.
Treatment & Disposal
  • Mowing 2-3 times a year for several years may slow the spread and reduce seed production. Mowing should be conducted during the bud stage and repeated when the plants re-bud. Mowing is especially effective when followed by herbicide application.
  • Cultivation alone will manage hoary cress when tillage begins at flower bud stage and is repeated every 10 days throughout the growing season. When combined with nitrogen fertilization, growth of grasses can increase and the rate of hoary cress invasion can be slowed.
  • Hoary cress is unpalatable to grazers.
  • There are no biological controls for hoary cress available at this time.
  • Chemical control is also an option. Before applying herbicides, read the label for full use and precautionary instructions.
  • For further information on the selection and application of chemicals to protect your crop, contact AgriService BC at 1-888-221-7141 or email AgriServiceBC@gov.bc.ca
Okanagan Distribution

Priority Level Definitions

Watch For - Poses a significant threat (very high risk) and does NOT presently occur in the region OR is relatively new to the region and is very limited in extent.
High - High risk/impact; limited population with significant potential to spread in the region.
Medium - Medium risk/impact; limited distribution – broader population distribution with potential to spread further in a region.
Low - Low risk/impact; may be widespread or not, may be of concern in specific situations with certain high values – e.g. specific agriculture crops. Some species may be treated primarily with biological control agents.