Redwood sorrel, Oxalis oregana
Just because Redwood sorrel is in the Oxalis family doesn’t mean you have to run for the hills in fear. But I get it—when most people hear “Oxalis,” they think of that noxious weed with the bright yellow flowers (Oxalis pes-caprae) that is frustratingly difficult to eradicate. This is not that. This Oxalis is actually quite tame, helpful in shady areas, and utterly charming. (I literally just ordered some for a client’s garden, I swear.)
Please keep reading to learn more about this easy, shade-loving Oxalis.
Hardy to USDA zones 7-9 and native to cool, moist coastal redwood forests all the way from southwest British Columbia to the San Francisco Bay, this shade-loving perennial ground cover flourishes in damp woodland areas and in the shadows of tree canopies, bushes, and ferns. While hiking my local Marin County coastal trails, I routinely spot attractive green carpets of this easygoing charmer and remind myself to plant more of it.
Redwood sorrel grows to no more than 8 inches tall and spreads by underground stems (rhizomes) to create soft dark green blankets of heart-shaped leaves with a blush of purple on its undersides. In the spring, sweet pinkish-white, star-shaped flowers emerge. Sometimes this plant can bloom off and on to early fall. Once the flowers fade, tiny fruits ripen and then explode, sending seeds in every direction. The seeds are actually favored by sparrows. But don’t worry, this plant won’t become a total nightmare. Pro Tip: If your Redwood sorrel ever gets a bit greedy, just reduce or eliminate its water intake.
Turns out that Indigenous American tribes in the Northwest used Redwood sorrel in their cooking and home remedies. Both the flowers and leaves are edible (the taste is a bit lemony and acidic) but because the plant contains oxalic acid, it can become toxic if too much is eaten at once.
Another interesting fact is that this plant exhibits a behavior called nyctinasty, which means it can open and close depending on temperature changes and the amount of light or darkness it receives. When strong light, heavy rain, or the human touch interacts with its delicate leaves, it folds them down into pyramids for protection.
- Plant a mass of them under redwood trees or tree ferns as they can deal with the heavy root competition.
- Add groupings to a shade, native, or woodland garden and let them naturalize.
- Pairs perfectly with ferns, wild ginger, coral bells, dogwoods, and huckleberries.
- A charming pollinator plant for bees and butterflies.
- Resistant to nibbling deer.
- Said to be fire-resistant.
Keep It Alive
- Make sure to provide a partly shady or full-on shady spot. Dappled sun is perfect too.
- Loves moist but well-draining, humus-rich soil.
- Water regularly to get it established then this carefree plant can tough out periods of dryness like a champ.
- You can find this plant at native plant nurseries and select garden stores.
For more ground covers, see: