- Author: June Walsh
Cardamine californica blossoms from January to May. Each flower is about 1/2 inch in diameter with four white to pale pink petals. The flower closes its petals in late afternoon as the sun goes down and nods before a rain. It grows by rhizomes. Its young leaves are edible but not necessarily tasty, more like bitter horseradish which becomes more pronounced with maturity.
After flowering and setting seed it becomes dormant in the summer, until the rains return. You can hand pollinate to increase seed set.
At Humboldt Botanical Garden it grows in the Moss Family Temperate Woodland Garden under spruce and fir, and among Iris douglasiana and trillium ovatum, all of which are naturally occurring on the site.
Cardamine hirsute; a weed! It is originally from Europe, the Caucuses and North Africa. It is an invasive weed in our Humboldt County gardens.
Though it is an annual which generally flowers in fall through winter, here in Coastal Humboldt it flowers and shoots its seeds ALL year. It is a member of the Brassica family and can be eaten as a bitter herb. It has many common names; pop weeds, bitter cress, hairy bitter cress and some unmentionable names.
Like many Brassicas it has seeds that burst explosively, casting the seeds far from the parent. If you want to rid your garden of these evil-doer invaders you need to remove the weed before it goes to seed (ha, fat chance!). Remove the pulled plants to the garbage, as the plant's seeds will continue to ripen after being pulled and our home compost bins are generally not hot enough to kill seeds.
Some sources suggest using Cardamine hirsuta as a winter cover crop! Late summer mulching is suggested to prevent germination. This gardener has not found much that is very effective but patience and diligence...don't turn you're back!
June Walsh is co-curator of the Moss Family Temperate Woodland Garden
and a UC Cooperative Extension Master Gardener
Source-The Jepson Herbarium, UC Berkely