Jacarandas: Growth Habits and Habitat

Q: Where would you suggest jacarandas be planted? They are beautiful when in bloom but messy. The petals track into the garage on the tires, and the sap is hard to remove. Will the roots cause problems as the tree matures?
— Wayna King, Camarillo
A: Jacarandas, also known as blue haze trees due to the clouds of violet-blue flowers that cover them this time of year, are native to semi-dry, subtropical regions of Brazil, Argentina and Bolivia. Because of its moderately dry habitat, jacaranda blooms most heavily after a winter with a minimum of rain and grows best in well-drained soil. In frost-free zones across the globe, jacaranda is the most popular ornamental tree. Locally, cold is its greatest enemy, and it should not be planted north of Granada Hills. Many jacarandas in Santa Clarita were killed during last January’s freeze.
In our heavily irrigated landscapes, jacaranda roots do not grow deep. As a result, they have been known to push up sidewalks and other paved surfaces, although not as consistently or predictably as Ficus roots. There is nothing you can do about their sticky blooms, the price you must pay for bringing their distinctive violet-blue beauty into your life. Once jacarandas bloom, you know that warm weather is on its way, since,, in Los Angeles,, they flower during a span of approximately eight weeks from late spring through early summer.
Q: The reason for this message is my bloomless hydrangea. Last year, my hydrangea had many small clusters of blooms. After the season, and when the plant was almost dormant, I cut each stalk about 1/3 down, fertilized and looked forward to huge blooms this year. What has happened?
— Sue Holtz, Mar Vista
A: It is advisable to cut hydrangeas back as soon as they finish blooming in mid- to late summer so that they can put on a strong flush of growth prior to the onset of cool weather. The flower buds of next spring are produced from August to October. If you cut back in the fall, you will likely remove all of the following year’s flower buds.
Hydrangeas remain, for me, mysterious plants. In the Valley, they must be protected from the slightest exposure to direct sun but still be exposed to excellent ambient light in order to size and bloom properly. In Mar Vista, since you are close to the ocean, you can give them a few hours of direct sun and still be confident in their ability to produce a respectable crop of flowers.
Still, I have planted hydrangeas all over Los Angeles with limited success. I would be interested in hearing from readers who have grown hydrangeas successfully. How do you do it?

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