(Updated as of 3/18/2011)
In creating the Wildflower Conservancy, I realized I would never be able to stop the dissemination of wildflower bloom reports online, and in fact, that's not at all my goal. I, too, have enjoyed and appreciated the information provided by those who report their findings. My hope is to provide education so that when people do visit the wildflowers, they will enjoy them responsibly.
Bearing that in mind, here's a list of online wildflower resources I have used every Spring for a number of years. Note: I have not included reports that have regularly focused on private property, altough I should explain that it's always possible some of these locations mentioned may be near private lands. If you see fences, gates or other barriers, respect them. Please honor these landowners' rights and do not trespass, throw trash or otherwise damage these areas. (Same holds true for public areas, for that matter.)
Carol Leigh's CalPhoto Wildflower Hotsheet - Carol's Hotsheet probably has been one of the best known resources for California wildflower hunters, particularly appealing because most who contribute are photographers. There is also a CalPhoto eGroup on Yahoo where people discuss various topics and often post wildflower reports and other news on a daily basis. [NOTE: As of 3/30/2010, Carol discontinued the Wildflower Hotsheet out of concern for the wildflowers being trampled and private property being trespassed upon, trashed, etc.]
Natural History Wanderings - Sandy Steinman has a wonderful blog that includes a great deal of helpful information as well as wildflower resources and reports.
Desert USA Wildflower Reports - Desert USA is very good for So Cal, Death Valley, Arizona, Utah, Texas and other desert locations.
Maturango Museum Trips Page- Located in Ridgecrest, Janet Westbrook of the Maturango Museum maintains this page. There is wonderful info on most all of the Kern County area, Mojave desert, Death Valley, Owens Valley, etc. -- All text, but well worth the read.
Theodore Payne Foundation Wildflower Hotline - The hotline usually starts in early March. It has a limited run of just a few weeks during the Spring, but it does provide good info for Southern California and portions of the Central Coast. You can also call the Hotline at (818) 768-3533. In addition, they have a wonderful links page for parks, preserves and recreational sites, many of which include wildflower info.
California State Parks - Discover Spring Wildflowers - Marvelous page with links to State Parks that are likely to have wildflowers.
U. S. Forest Service - Celebrating Wildflowers - Includes information on wildflowers and resources with links to specific regions: Alaska, Eastern, Intermountain, Northern, Pacific Northwest, Pacific Southwest, Rocky Mountain, Southern and Southwestern. Each Region page provides further links to wildflower viewing areas within the Region. For example, Pacific Southwest Region (includes California).
California Wildflowers - Bureau of Land Management - Several regional offices of the BLM offer wildflower reports, but this one covers the whole state. More helpful links for each region as well. Be sure to check out the chart for peak blooming periods throughout the state.
Antelope Valley Poppy Reserve - Wildflower hotline info is listed here along with other information about visiting the Reserve. You can also call the Hotline: (661) 724-1180.
Anza-Borrego State Park- Scroll down for wildflower info and a link to the current report (March 4th as of this post.) Call the wildflower hotline at (760) 767-4684.
Anza Borrego Foundation - Wildflower Page - More information on what's blooming in the Anza-Borrego area..
Anza-Borrego Desert Natural History Association. - One of the best resources on current wildflower conditions for this area. They also post current wildflower reports.
Joshua Tree National Park Wildflower Viewing - Periodically, has updated seasonal reports.
Death Valley NP Wildflower Report - This links to the National Park's wildflower report, often provided by Ranger Charlie Callaghan.
Visit Kern - Wildflower Hotline - Sponsored by the Kern County Board of Trade, check here for current reports on wildflowers in Kern County. There are also maps, a list of locations and wildflower species info as well as helpful links to other wildflower resources.
Kern County Wildflower Blogspot - It appears this blog is posted by the same folks who do Visit Kern. Has reports, but little else at the moment.
Tejon Ranch Conservancy Although much of the Tejon Ranch is private property, a conservancy has been established to preserve most of the land in its natural state. The public is allowed to access the property, but only during scheduled events, hikes, etc. They also have provided a very helpful guide to wildflowers in the area.
Carrizo Plain National Monument Wildflowers - The BLM out of Bakersfield provides this report along with images of wildflowers typically found on the Plain. Call the Goodwin Education Center to check the latest road conditions, etc. (805) 475-2131.
Santa Monica Mountains NRA - Wildflower reports and a page devoted to what's blooming that identifies species and include photos.
Figueroa Mountain - Ranger Helen Tarbet of the USFS sends out a wonderful newsletter on the conditions at Figueroa Mountain. Contact Helen at (805) 925-9538, ext. 246, or email her at email@example.com. You'll need an Adventure Pass on Figueroa Mountain. They can be purchased from the U.S. Forext Service online or at REI and Big Five. A copy of her latest report is occasionally posted here online.