Bloom Reports from the Anza-Borrego Desert: 2023-2024
Table of Contents
Latest Summary of Bloom Status
Bloom Reports from Individual Hikes This Season
Links to Other Webpages on Anza-Borrego Desert State Park Blooms
Background Information for Bloom Reports from the Anza-Borrego Desert
Older Bloom Reports from 2009 to present
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| Fig. 1. Left: Prunus fremontii, desert apricot, blooming along S2 in the San Felipe Valley. Right: Phacelia pedicellata, pedicellate phacelia, blooming in Torote Canyon. Both photographs taken on 28 February 2024 by Tom Chester.
Click on the pix to go to the iNat obs of each, showing exactly where those photos were taken. | |
Latest Summary of Bloom Status
Summary as of 7 March 2024
The desert floor from 200 to ~1000 feet elevation has now begun full bloom. We walked across Clark Valley on 5 March 2024, and the bloom there is excellent, as good as it gets. The Henderson Canyon Road flower field is gorgeous, and has been so for a few weeks now. Both areas should remain in full bloom for at least several weeks.
Other areas are not yet in full bloom, but the number of species in bloom is climbing rapidly; see Fig. 2. After having just 10 to 30 species in bloom on each trip from October 2023 to 1 February 2024, we are now seeing a linear increase in the number of species in bloom with time. We are only slightly behind the trajectory of the bloom in 2009-2010, when the general peak bloom began in mid-March 2010.
Fig. 2 shows a plot of the number of species seen in bloom on each desert trip so far this year, with a comparison to three other previous years.
Fig. 2. Plot of the number of species seen in bloom on each desert trip so far this year (heavy black line), with a comparison to three other previous years. The data have been smoothed by averaging each trip with the previous trip and the subsequent trip, except for the first and last trip of this year. The number of plants in bloom has been increasing linearly since the lowest bloom numbers of mid-January.
The sandy area just north of Henderson Canyon Road is the easiest area to access that has a good bloom. Pictures of the excellent bloom there from sand verbena, Abronia villosa, dune evening primrose, Oenothera deltoides, and hairy desert sunflower, Geraea canescens, are flooding the internet. See, for example, posts in Fred and Carla's Facebook page and their public Facebook page.
However, most areas at low elevations are still two to four weeks away from peak bloom, and higher elevations are even farther away. For example, there are hardly any blooms seen along the entire length of S2 except for the hillside of Prunus fremontii shown in this iNat post and in Fig. 1. And although there have been ~40 species in bloom on our last hikes, most of those species have just a few plants in bloom.
That doesn't mean there aren't good displays in those areas. Chuparosa, Justicia californica, is blazing away in many places.
Many of our favorite flowers are beginning to bloom, such as desert lily, Hesperocallis undulata, and fishhook cactus, Mammillaria dioica.
And although you might see only 40 or 50 species in bloom on a given hike, there have been 149 species marked as being in bloom here in the last two weeks as of 4 March 2024. The number will be higher if you click that link on a later date. There are even more observations of plants in bloom that haven't been tagged as being in bloom. The most frequently posted, and tagged as being in bloom, species are desert lily, Hesperocallis undulata (145 posts); brown-eyed evening primrose, Chylismia claviformis (62 posts); hairy desert sunflower, Geraea canescens (47 posts); and desert sand verbena, Abronia villosa (45 posts).
Note that some areas of the desert floor have been taken over by Sahara Mustard again, and without some severe drought years in the future, it will eventually displace the wildflowers in the Borrego Valley again. The fabulous area north of Henderson Canyon Road that looks so good this year, and the area along Coyote Creek Road north of the pavement end of Di Giorgio Road, were essentially completely devoid of wildflowers by 2007 after Sahara Mustard took over. It took three consecutive years of severe drought to deplete the Sahara Mustard seed bank, to knock out the mustard so that our native wildflowers could make a fabulous display again; see Sahara Mustard Reduction in Numbers in the Borrego Desert Floor in 2015. Since 2015 the number of plants of Sahara Mustard has been increasing every year.
You can explore the state of the bloom yourself from the comfort of home with the iNat 5,157 observations of 352 species posted at iNat since 19 February 2024 (numbers are as of 4 March 2024; your numbers will be more as more obs are added from later dates). Click on "Filters" in the upper right to change the date range if you want to see only very recent observations.
Note that some of the species in bloom with only a few observations may be represented by only a single individual, or a small number of individuals. Also, how many and which species you see in bloom on your hike is largely determined by where you hike and how far you hike. Many species are restricted to a certain elevation range, or certain locations.
Click on the "Map" tab at the link and you can zoom into the map to see where the reports are. Once you zoom into a given area, click on the "Redo search in map", or use the rectangular or circular area tool to circumscribe your area, to find out how many flower observations there are in your desired area. Each observation gives the date and time of observation, and the latitude and longitude for each observation, which is plotted on a map so you can see where it was observed (rare species have obscured coordinates, which have a different symbol on the map and wildly-inaccurate coordinates from the obscuration).
See also previous versions of this page.
Background information on this year's bloom.
This is the third year in a row with good monsoonal rain in the Borrego Desert, which makes this yet another year in which the desert blooms consist of two very different components.
The first component is from plants that responded to monsoonal rains, specifically the unusually-good rain from the remnants of Tropical Storm Hilary on 19-20 August 2023. Hilary dumped seven inches on both Ranchita and Mt. Laguna, and the desert floor received a widespread two inches.
That rain resulted in widespread appearance of monsoonal species on the desert floor, especially Pectis papposa, chinchweed; Kallstroemia californica, California caltrop; Palafoxia arida, Spanish needles; and Allionia incarnata, trailing four o'clock. Those plants were probably in full bloom from mid-September through mid-October, but their bloom quickly declined after that, which is usually the case. Last year, their bloom hung on much later, since the rain that year came a month later.
As of 10 January 2024, the Kallstroemia plants were essentially all finished fruiting and dead, as were most of the Pectis and Palafoxia plants except for scattered individuals. Most Allionia plants on the desert floor were dead and finished, but increasing numbers of them are still alive as one heads into the hills west of Borrego Springs.
That August rain also germinated a very small number, in most places, of our usual spring plants in the sandiest areas of the desert, such as Abronia villosa, desert sand verbena; Perityle emoryi, Emory's rock daisy; and Geraea canescens, desert sunflower. There are many fewer plants of those species this year than came from the September rain in the previous summer. For example, last year there were spectacular carpets of sand verbena from October through March. This year, there are only isolated plants of those species in most areas. Those plants began blooming in October, and are still going strong as of 4 March 2024. See a map of those species, plus Palafoxia, observed since 1 December 2023, showing where those sandy areas are.
The best display from those plants are Geraea plants in a small part of the area north of Henderson Canyon Road, at 1.5 miles east of Borrego Canyon Road. Some scattered Badland canyon areas are filled with Perityle plants, such as at Blackwood basin wash and Diablo Dieguenos Loop.
There is also a good display of flowers from Malacothamnus enigmaticus in the Salt Creek area of Mason Valley, southwest of the Butterfield Mobile Home Park. There are hundreds of plants in bloom there, many covered with flowers. See the 19 iNat posts tagged as having flowers since 20 December 2023. This species is a fire-follower, and most of those plants will be dead in a few years.
As is typical, many plants of Xylorhiza orcuttii, Orcutt's aster, are in bloom in the Badlands.
The second component comes from the usual late winter / early spring bloomers. We have had enough winter rain to make a good display of those plants in most, but not all, areas, with widespread germination noted.
A few tenths of an inch of rain fell on 13-14 November 2023, and a half to 3/4 of an inch fell on 21-22 December 2024, with both rains widespread on the desert floor. The desert received another widespread 1.0 to 1.5 inches of rain on 21-22 January 2024, which was enough to produce widespread germination. Another widespread 0.5 to 0.9 inches fell on 4-9 February 2024, and another few tenths on 19-21 February 2024. This is exactly the kind of precipitation pattern needed to have a good spring bloom. The lack of hot weather has helped as well.
Bloom Reports from Individual Hikes This Season
The latest bloom reports are given first (i.e., the reports are in inverse order of time). As detailed immediately above, you can see a map of where the hikes were from any linked iNat post of the species in bloom.
For many more bloom reports, see Anza-Borrego Wildflowers Bloom Report by Fred Melgert and Carla Hoegen.
Bloom Reports not yet added to this page
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For many more bloom reports, see Anza-Borrego Wildflowers Bloom Report by Fred Melgert and Carla Hoegen.
Links to Other Webpages on Anza-Borrego Desert State Park Blooms
Anza-Borrego Wildflowers Bloom Report by Fred Melgert and Carla Hoegen, often with daily wildflower updates.
All iNaturalist observations in the Borrego Desert since 20 December 2023 (click on "Filters" to change the dates; there were 1,984 observations of 272 species posted at iNat as of 12 January 2024)
Wildflower Updates from the Anza-Borrego Desert Natural History Association.
Anza-Borrego Desert State Park official site, with wildflower information on it. When they start producing current wildflower reports, click on the link near the top with the word Update, which might be updated weekly.
DesertUSA Anza-Borrego Desert State Park Wildflower Reports
Anza-Borrego Foundation and Institute Wildflowers and their Anza-Borrego Desert State Park Wildflower Hotline: (760)767-4684. "Information on this recording is updated regularly."
Theodore Payne Wildflower Hotline (Reports begin the first Friday in March)