Bloom Reports from the Anza-Borrego Desert: 2019-2020

22 January 2020

22 January 2020
Fig. 1. Two species currently blooming that normally are among the first Borrego Desert species to bloom each year. Left: Prunus fremontii, desert apricot, in Culp Valley. Right: Mammillaria dioica, California fish-hook cactus, near the west end of the Henderson Canyon dirt road.
Click on the photos for larger versions.


The number of species in bloom is gradually beginning to increase from the very low numbers of plants in bloom we've seen over the last month of just five to 20 species per trip. There are now at least 35 species blooming below 3000 feet elevation on the west side of Borrego Springs, and it is fairly easy to see 20 species in bloom on a given trip, especially if you count ones in bloom along S22 / Montezuma Grade. See, for example, the heavy black line in this plot, from the 2013 to 2014 bloom year to get an idea of how rapidly the bloom might increase over the next two months.

Although we have had small numbers of widely-scattered plants in bloom for a month or two, those plants are rarities that came from the light and variable rainfall on 26 September 2019. We're now seeing the usual perennial plants that begin to bloom in most Januaries, such as Prunus fremontii in Culp Valley at 3000 feet elevation and Mammillaria dioica on the desert floor near 1000 feet elevation; see Fig. 1.

Pectocarya recurvata, curvenut combseed, one of the first annual species to bloom since it blooms when it is a few inches high, is now in full bloom in many places, but most people won't notice it since its flowers are so tiny. There are also a small number of other seasonal annuals just beginning bloom, with the first flower spotted of Phacelia distans, common phacelia. Many Phacelia distans plants are now forming buds, and will begin blooming in the next two to four weeks. Several popcorn flowers, Cryptantha species, have their first flowers, too.

Along S22 from Culp Valley to Borrego Springs, there are ~50 large shrubs of Prunus fremontii in full bloom, along with ~50 plants of Encelia farinosa, brittlebush, in full bloom that responded to the late September rainfall. The vast majority of Encelia farinosa plants will not be in bloom until March. Some ocotillos are in bloom, along with some plants of desert lavender.

It is too early to know what kind of wildflower season we will have. Many species don't even germinate until it gets warmer, typically in February, so there is little to go on yet to predict the future bloom. From the above-average rainfall in the desert in the last three months, one would expect a better than average bloom. But so far, in most places, we see no evidence that plants other than the non-native Brassica tournefortii, Saharan mustard, are responding to the good rainfall. And, of course, a good bloom year depends on receiving additional rainfall. However, the lack of response by the plants might simply be due to the cool weather in the desert in the last month.

Although the rainy season started out wonderfully, there has been no significant rainfall since 28 December, almost a month ago, and the much-better-than-average rainfall is quickly approaching just average rainfall in the Borrego Springs area and west. Average rainfall typically produces average flowers, not a superbloom. For a complete summary of the rainfall so far by location, see Fred Melgert and Carla Hoegen's rainfall graph.

The way to bet right now (this is not a prediction, just a suspicion), is that it is most likely NOT going to be another great wildflower year unless we get some additional significant rain in the next month. For unknown reasons, despite the good rainfall to date, some plants have already voted to start producing flowers when very small, and just a few flowers at that. For example, Brassica tournefortii is already in fruit along the Culp Valley Roadsides, and around the parking area at Second Crossing! This is very surprising January behavior.

Our suspicion is that it will be a typical decent flower year, with mostly-small annuals present in most places, especially the open areas, and decent to good displays of flowers on larger plants in some areas, especially the canyons on the west side of Borrego Springs.

The temperatures in the desert have been cool, which is exactly what we want for a good bloom, allowing the plants to grow larger before blooming. This means we will probably not have any widespread blooms until mid-February 2020 at the earliest. See the reports and graph in Fred Melgert and Carla Hoegen's 2019-2020 bloom report to see the actual progress of the bloom this year.

Unfortunately, Sahara mustard is making a comeback in many areas, and will choke out the wildflower bloom in those areas, such as roadsides along S22 east of Borrego Springs west of the Thimble Trail, and probably in the Borrego Dump area. One area near the eastern end of Henderson Canyon Road already went from nearly 100% native plants to nearly 100% non-native weeds in just two years from 2017 to 2019.

See Sahara Mustard Reduction in Numbers in the Borrego Desert Floor in 2015 for how wonderful it was immediately after the drought years. Sahara mustard still hasn't made a full comeback in some good wildflower areas, such as in most of the desert sunflower field along the Henderson Canyon Road, and the area north of the end of the pavement for Di Giorgio Road, probably because people have been weeding it out of those areas. Those areas should still be decent for native wildflowers this year, although they will be small without further rain.

Last year, we had excellent rain in a swath of areas on October 12 and 13, which produced good annual germination, which resulted in blooms beginning in December. That didn't happen this year. The late September rain was too early to germinate winter annuals on the desert floor, except in an extremely few isolated locations where water runoff was concentrated. The late September rain did germinate a lot of roadside annuals at higher elevations such as Culp Valley, mostly Sahara mustard.

The best source now to look for places to hike that have flowers you might be interested in, is the crowd-sourced iNaturalist to pick places that have species that you are interested in. You can get almost daily updates on what is blooming, or not blooming, in the Anza-Borrego Desert, as well as where species were found. Click on "Filters" and select a date range to see the observations from that period. For example, here are all the observations on 1 January 2020 and later, which had 1,136 observations through 23 January 2020. Each observation gives the date and time of observation, and the latitude and longitude for each observation, which is plotted on a map for you so you can see where it was from.

If you find species at iNat that you are interested in seeing, you can search just for recent observations of those species, and go where you see the most observations. Here is an example from last year: if you had wanted to see ghostflowers in bloom in early March 2019, there were 43 observations posted between 20 February and 2 March 2019. Clicking on the "Map" tab shows there were six separate locations where observations have been posted.

Links to Other Webpages, etc. on Anza-Borrego Desert State Park Blooms

Anza-Borrego Wildflowers Bloom Report by Fred Melgert and Carla Hoegen, often with daily wildflower updates.

iNaturalist observations in the Borrego Desert since 1 December 2019 (click on "Filters" to change the dates)

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 (link will be supplied when they create their page this year) 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)

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Comments and feedback: Tom Chester
Updated 25 January 2020