Posted by: Sandy Steinman | January 14, 2019

Anza-Borrego Wildflowers 1/11/19

Anza Borrego Desert Natural History Association report

January 11, 2019
Bloom Prediction for 2019
Desert Research Botanist Kate Harper has been making field observations over the past weeks and has just issued her prediction for the 2019 bloom season. Please read her report in its entirety, but the bottom-line is that we are on track for a very good bloom this season with just a couple of weather conditions that could alter it.

Anza-Borrego Desert State Park 2018-19 “Season” Bloom Analysis and Prediction
by Kate Harper
Desert Research Botanist
Rain Analysis Related to Blooming

We appear to be heading into a 2-pulse 2018-19 “Season”.

What has triggered the first pulse of blooming?

We had significant rain in spotty areas of Anza-Borrego Desert State Park (the Park) on October 12, 2018. It was still hot in the Park, but it was cooling off from the peak summer heat. It appears that the temperature was still warm enough to trigger the germination of some monsoonal plants (summer storm triggering plants), and just cooled down enough to trigger the germination of some “spring” plants (calendar winter, but what we call in the desert spring).

So, right now, in mid-January 2019, we are having the beginning of a bloom! BUT, just in the spotty areas that received the thunderstorm rain on October 12, 2019. Unfortunately, none of the popular close-to-town flower field areas are included in this spotty early bloom.

What has triggered the second, more common pulse of blooming?

The Park received 0.39 inch of rain in a November 29-30, 2018 storm. This is not enough rain to trigger widespread germination, BUT it is enough rain to soften the dry surface of the soil and to make the soil receptive to additional rain without run off. And, so what do you want after such a preparatory rain? A storm of at least 1 inch. And, the Park got it! A storm event on December 5-6, 2018 delivered 1.05 inches of rain. Now we have enough rain to trigger widespread germination of “Spring” annuals.

Think of the desert in the “Spring” like you would think about planting a garden. After you have the seeds in, all experts suggest “give your garden a good soaking”. That is the December 5-6, 2018 storm that delivered 1.05 inches. Then, what do the garden experts tell you? They say, “Water at regular intervals.” And, voila! The skies have delivered just such a watering regime, so far: A semi-soaking on December 31, 2018 of 0.52 inch. A nice interval watering on January 6, 2019 of 0.11 inch. And, right on cue, another interval watering of 0.14 inch on January 12, 2019!

So, does this guarantee us a lovely “Spring” Bloom this year? Almost.

Only 2 kinds of events could derail a lovely “Spring” bloom this year: multiple days of below freezing temperatures or multiple days of super hot temperatures. Either of these could impact the plants. BUT, barring those events, we are ON for a lovely year to be in the flower-filled Borrego Desert!


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