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San Diego plants act like it’s spring again after August drenching

Tropical Storm Hilary arrived in San Diego on Aug. 20. It rained all day, dropping at least two inches in most places.

“It was shocking, to be honest with you,” said Southern California native and garden expert Nan Sterman.

“Except for the six years that I was in university and hanging out afterward, I have lived my entire life in Southern California,” Sterman said. “And I have never ever seen a summer rainstorm like we saw a couple of weeks ago.”


All that water, when the local landscape should be hot and dry, made our plants act pretty strange. Tipuana trees were blooming a second time. Native plants like ceanothus were showing new growth when they should have been dormant.

Plant experts saw surprises all over town.

“In Black Mountain Open Space Park, for example, the Mission Manzanita, those beautiful gnarly shrubs with the orange brown trunks, they had flowers there in September,” said Alex Kunz, a member of the California Native Plant Society.

Kunz said lemonade berry and sugarbush plants are also growing new buds right now.

To San Diegans, rain is almost always welcome, especially a gift like the one Hilary delivered. This means it’s become a good time, though an unusual time, for us to enjoy a flowering landscape. But there might be a downside to the storm’s generous soaking.


In San Diego’s backcountry, seed pods are germinating. That means we’re going to get a lot of new grasses and weeds.

“One thing we have noticed is that it has really caused a big increase in the sprouting of invasive and exotic species,” said Tim Chavez, CalFire assistant chief for wildfire forecast.

“I’ve noticed in our local area, the Russian thistle, or what most people call tumbleweeds …Oh my gosh! They are really taking over in a lot of places,” he said.

Those weeds and grasses, of course, could provide more fuel for fire when Santa Ana winds start blowing.

Sterman, who hosts “A Growing Passion” on KPBS TV, added that native and drought tolerant plants don’t really want irrigation or rain this time of year. She adds that moisture in the soil could make their roots vulnerable to fungi.

“That’s what they evolved to do is to live through that heat. If you water and you water too much, then the phytophthora and other pathogenic fungi develop and they attack those plants and that’s when you get root rot,” Sterman said.

The weather in California this year has been unusually wet. It was a long spring and a late summer. Chavez said he’s never seen a growing season last quite as long as it did this year.

All plant experts agree that August rainstorm was such an unusual event that we’re in uncharted territory, and predicting its environmental effect may have to be our best guess.