Early Blooms: What Does That Mean for Spring 2020?
Sandyland bluebonnets and groundsel - 3/19/2019, Anchorage, Texas
[I wrote nearly the exact same article last year. In fact, I am using it for a template this year]
10 Second Summary: Bluebonnets and other cool season wildflowers will likely bloom 6 to 10 days earlier along heavily traveled roads, in urban areas (especially the I-35 corridor) and south-facing locations. Other areas could be on the early side of normal times – so for example parts of the Hill Country could see fields in bloom in the last week of March rather than the first week of April.
The Nerdy Details and Facts
For nearly a month now reports have been coming into Texas Wildflower Report (https://www.facebook.com/TexasWildflowerReport/ ) or in private message about sightings of early bluebonnet and other wildflower blooms.
What is happening this year, and does this mean the Spring 2020 Wildflower Season will be much earlier this year? As I mentioned in the 2020 Outlook, it does appear that roadsides and areas within urban heat islands along I-35, I-10 and I-37 will bloom much earlier this year and likely much earlier than fields. This means we might see a split season where the roadsides and urban areas peak well before the fields do. This is not totally unusual, especially when we see a warmer December and January which we did this year.
December-January temperatures overall were above normal and, in some parts, the warmest in the past 20 years. Mason County's average temperature for December 2019-January 2020 was the warmest in the past 20 years, coming in at 4.5F degrees above the mean for the base period of 1901-2000. The average minimum temperature for Mason County was 37.5F or 3.1F above the mean and 17th warmest on the list since 2000. - https://www.ncdc.noaa.gov/cag/county/time-series
For the past 30-day period from 2/23/2020, the max temperature for most of Texas was below normal, but the minimum temperature was above normal. - https://www.cpc.ncep.noaa.gov/products/tanal/temp_analyses.php
Why would this make a difference to our bluebonnets? Our bluebonnet species are winter annuals. Winter annuals germinate in the fall and go through the winter as small plants called rosettes. Most winter annuals need a cold spell to stimulate or induce flowering in the spring. This need for the cold spell is called vernalization (there is some debate about how, why and if, but the general consensus is they need the cold). I have not yet found any references that state exactly how long a period of cold that our bluebonnets need. One source indicates that the vernalization requirement (https://cns.utexas.edu/news/vernalization) can be four to 12 weeks for winter annuals.
And from other research, it is clear that plants do not just respond to short periods of warm temperatures that break up a winter. So, the plants respond by flowering only after a specific time of cold followed by a specific time of warming temperatures. It appears parts of Texas went through a period of cold in November that was followed by a period of warm temperatures in the past 60 days. It could be the vernalization requirement for bluebonnets in those locations was met and the warm period following was long enough to start the process of flowering.
Another wild thought, is that we might already be seeing a new adaption in at least one of our bluebonnet species that will be blooming earlier as our winters are warming – it is wild thought, but it is already happening with other species of wildflowers in California. - https://www.scientificamerican.com/article/many-plants-can-adapt-whe/
Official 30-Day Forecasts, issued February 20, 2020 calls for below normal temperatures and equal chances for rain. - https://www.cpc.ncep.noaa.gov/products/predictions/30day/
Official Outlook for Mar-Apr-May 2020 calls for above normal temperatures and equal chances for rain. -https://www.cpc.ncep.noaa.gov/products/predictions/long_range/seasonal.php?lead=1
Hopefully this mean we will see enough rainfall, cooler temperatures for most of March and plenty of sunshine mixed in. If this holds true then we should see at least most fields hold off until the usual time for them to bloom, but even they might start a bit earlier in their normal range. I still think based on all of the reports of blooms that the roadsides will bloom earlier this year, especially along roads in the urban heat islands.
What happened in 2019?
We had a similar situation last year with more rain in the fall, but warmer than normal temperatures in December-January and we saw some fields in bloom south/east of San Antonio in mid-March (see photo above) and some early blooms along major roads in the Hill Country by the 3rd week of March. This was about 6 to 10 days earlier. Mason County had roadsides in full bloom and blooms into fields near roads in the last week of March (https://pbase.com/richo/image/169001066 ), but then we had other fields in Mason County in full bloom in the second week of April (https://pbase.com/richo/image/169070793).
You can check out how 2019 progressed based on my experience for the Hill Country and areas South/East of San Antonio, by scanning through my gallery at: https://pbase.com/richo/texaswildflowers2019&page=all . The photos are arranged from earliest to latest and at least a County is given for the location.
NOTE: The 2020 Spring Wildflower Season Outlook and our Wildflower Updates are not a forecast, they are merely a look at what the data and past record suggests might happen or happening. Attempting to forecast Texas weather or wildflower seasons is a futile effort laced with disappointment. One would have a better chance of predicting the Final Four one year out than to try and predict Texas weather or wildflower seasons. But we try our best to use the data to give us a clue about how the season might develop while remembering that one day it could be snowing in Texas and the next day be t-shirt weather. And Texas weather goes hand-in-hand with how the wildflower season will develop.
ENSO: Recent Evolution, Current Status and Predictions - https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf
Many Plants Can Adapt when Climate Goes against the Grain - https://www.scientificamerican.com/article/many-plants-can-adapt-whe
Plants ‘Remember’ Winter To Bloom In Spring With Help of Special Molecule - https://cns.utexas.edu/news/vernalization
2020 Spring Wildflower Season Outlook - http://www.wildflowerhaven.com/eBooks
Warming winters across the United States - https://www.climate.gov/news-features/blogs/beyond-data/warming-winters-across-united-states
When Should I Come to See Texas Wildflowers? - http://www.wildflowerhaven.com/Articles/Texas-Bloom-Times