Wood Sorrels (Oxalis species)

pink wood sorrel (Oxalis bowiei)

pink wood sorrel (Oxalis bowiei)

Q: I have a problem with a weed growing in my yard. It has leaves similar to a three-leaf clover and produces a pink flower. I have been told it is related to oxalis. It also originates from a bulb sometimes as tiny as 1/4 of an inch. Invariably when I try to pull them out, the root separates from the bulb, only to increase their reproduction. I have tried removing the soil down to the depth of the bulbs and triple screening the soil to remove the bulbs. Is there any weed killer that will also destroy the bulbs?
– Bob Gilbert, Van Nuys
A: Your clover look-alike is Oxalis oregana, also known as redwood sorrel because of its redwood forest habitat. In small gardens, redwood sorrel could be a nuisance since it would take over limited growing space. In large gardens, it may be cherished as a ground cover that demands little attention. If you wish to eliminate oxalis of any type, you will need to use herbicide – available at most nurseries – designed specifically for it. The closely related pink wood sorrel (Oxalis boweiei) is a more manageable species.

When people ask me to recommend perennial plants for their garden, it turns out that what people generally want is something that blooms most of the year, requires little water, needs pruning only occasionally, and is seldom bothered by pests.
They typically settle for lavender, lantana, ivy geraniums, begonias and floribunda roses.
At the Soka University garden in Calabasas, very little is blooming right now, but that does not diminish the beauty of the plants on display, all of which are indigenous to the Santa Monica Mountains.
It takes discipline and courage to confine your horticultural vision to a particular geographical domain, especially when it happens to be your own back yard. Gardeners, you see, tend to be a defiant group and will go out of their way to plant what they have no business planting, as far as local climate and soil conditions are concerned.
Take azaleas, for instance, which are native to Asia. No plants are more out of place in Los Angeles than these. Because of our alkaline soil, they require lots of amendments at planting time and fertilization several times after that. Still, just about everyone wants azaleas, even if their life expectancy in our gardens is short.
But when you see the spreading rush (Juncus patens) at the Soka garden, you will quickly put azaleas out of your mind. You will marvel at green quill leaves handsomely marked with brown bands. You will imbibe the mint fragrance of yerba buena (Satureja douglasii) and the raspberry aroma of Santa Susana tarweed. Ribes indecorum is a currant with pendulant white flowers while California buttercup (Ranunculus california) has a bright yellow bloom that needs no flowery description from me.
The garden at Soka University is free to the public. You can arrange a visit by calling (818) 878-3741 or go to www.soka.edu/calabasas for a schedule of upcoming events.

TIP OF THE WEEK: Now is the time to trim back ivy, gazania, periwinkle (Vinca Major) and ivy geranium ground covers. These plants will benefit from a severe pruning prior to the onset of spring weather. Trim established ground covers back to a height of 2 or 3 inches.

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