Plants, Stone, California Landscapes




‘For the first time since 1850, San Francisco will log .00 of rain for the month… The previous record low rainfall was 0.06 inches set just last year. In January 2013, 0.49 inches of rain fell on San Francisco… The past three Januaries in San Francisco are among the five driest on record. This has brought the average for the past ten years down to 3.03 inches, dramatically lower than the 30-year normal of 4.55 inches.’

‘All I know is that I don’t know.’ Operation Ivy

How will a January without rain affect my gardens? How would I know? I haven’t ever seen a winter like this. As a rule of thumb, the plants don’t need a lot of water this time of year. The evapotranspiration rate doubles in February and then doubles again in March, so January isn’t a real critical month in terms of rainfall for the garden. Factors like day length, dew, winter dormancy, and low plant metabolism keep the plant water needs low, even when the weather forgets that it’s the rainy season.

But I don’t really know the effect of six weeks without water in the heart of our rainy season. Some of our clients turned their irrigation on, some left it off. A couple of gardens are weather-satellite controlled, another has a low-budget rain sensor; who knows how often those systems ran. My parents turned their irrigation back on to full summertime levels (I guess they didn’t believe me about the evapotranspiration), and the elderly tenant of a friend never turned the irrigation off at all, not even during the heavy rains in December. And I’ve realized, looking at some of these gardens, I can’t really tell the difference. I don’t see signs of drought stress in the unwatered gardens and I don’t see signs of over-watering in the over-irrigated ones. If I can’t see a difference, it’s probably best to save the water, but who knows, maybe the effects will start to show later in the year. I just want to see it rain.

One Response to “Rain!”

  1. February 10th, 2015 at 9:20 pm

    James says:

    Congrats on the rain. We had a dry January too down here, though it was a hair moister than your month. I always seem to have new plants in the ground, so those got watered some of the time, though I know I’ve lost a couple for sure. And the patches of seeded wildflowers got some water. The established plants, though, seemed to make it through. What would our East Coast friends think of our having to water in the dead of winter?

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