Garden Detective

Garden Detective: Yucca surprises with a giant stalk

Garden Detective: What’s happening to this yucca? It’s starting to bloom.
Garden Detective: What’s happening to this yucca? It’s starting to bloom.

Q: I have had this yucca cactus in my yard for almost 20 years and last month it started to sprout this shaft. It is almost 12 to 13 feet tall. Can you give me any information on this phenomenon?

Robert Andrews,

Rancho Murieta

A: Hopefully, you enjoyed your yucca’s spectacular bloom. Judging from your photo, it appears that your plant is a Yucca whipplei, a native to Southern California mountains and much of the California coast. Nicknamed “Our Lord’s Candle,” it’s a member of the agave family and can have similar growing habits – including that impressive flower stalk.

An evergreen shrub with gray-green leaves, this cold-hardy yucca forms a dense rosette that grows rather slowly for several years. The leaves have needlelike tips that can be very sharp.

Once the plant reaches its maturity, it sends up a flower shoot such as yours, usually in late spring or early summer. That massive stem can reach 16 feet tall and produces hundreds of creamy-white 1-inch blossoms in long spikes.

After the flowers fade, the stalk gradually browns and becomes woody. The whole plant slowly dies along with its huge flower stalk. But at the base of the mother plant should be offsets, or “pups.” These young plants will replace their parent, basically starting over the whole cycle.

These pups also can be divided and transplanted. Give them some space; the rosettes can reach 3 feet tall and 6 feet wide. Yucca prefer full sun and good drainage. A low-water shrub, they prefer infrequent deep irrigation; water just once or twice a month after the plants become established.

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