How Southern California’s heavy rains will affect the wildflower bloom

What can we expect this year from our wildflower bloom?

Due to early rains, we have already begun to see significant wildflower eruptions. The problem is that our heavy early rains also brought out more non-native plants, aka weeds, than usual and these could crowd out a lot of our natives.

There is a good-news-bad-news dynamic when it comes to wildflower bloom. Winter rain and snow in California are always welcome, since they provide water for people and agriculture. So the arrival of abundant winter precipitation is always good news. However, wet winters also result in the proliferation of non-native annuals such as brome grasses, mustards, and tumbleweed. Since the 2024-25 winter was on the dry side — 7.74 inches of rain compared to our average of 14.25 inches — some of the seeds of aggressive non-natives may have lost their viability.

Yet many non-native seeds need two dry winters in succession to lose their viability, and our 2023-2024 rainfall was heavy with 25.19 inches recorded. This year, we have already accumulated 21.7 inches of rain (as of mid-February); that’s bad news when it comes to having wildflowers dominate the natural landscape. It is only after a succession of dry winters that we see our most spectacular wildflower displays when rain finally comes. Once non-native seeds are no longer a threat to germinate, native seeds that can lay dormant for decades will have exclusive access to winter rain.

It is also true that — following a dry winter — south-facing slopes will bloom more than north-facing slopes since the former would have been hotter and any non-natives that sprouted would have died before they could flower and set seed, leaving the terrain open for drought-tolerant native wildflowers to finish their life cycle and drop seeds for next year’s bloom.

The widely dispersed black mustard (Brassica nigra) was introduced by Spanish missionaries in the late 18th century, who planted it for culinary and medicinal purposes. It spread from their church gardens along El Camino Real throughout the state. Black mustard roots exude allelopathic compounds that prevent seeds of other plants, including natives, from germinating.

As for invasive Eurasian brome grasses, their seeds arrived embedded in the ballast of ships that docked in San Francisco during the mid-nineteenth century and beyond. Later replaced by water, ballast at that time took the form of sand, soil, or rocks loaded in the bottom of a ship to give it stability as it sailed the seas. Upon reaching land, the ballast was emptied, to be replaced by cargo on its return voyage. Brome seeds sprouted where the ships docked, and the rest, as they say, is history.

Another famous weed arrived in California and throughout the West, thanks to Russian flax farmers who settled in South Dakota in the 1870s. The bags of flaxseed they brought from home contained the seeds of a weed emblematic of the Wild West: tumbleweed (Salsola tragus). Once it dies, tumbleweed detaches itself from the ground and is transported long distances by the wind — doing somersaults and dropping its seeds along the way until, in our case, it arrived in California. A single plant may yield 200,000 seeds whose germinating seedlings displace natives. Tumbleweed’s lone saving grace is the edibility of its young shoots.

For weekly updates, recorded on Fridays, of wildflower displays that merit a visit from March through May, call the Theodore Payne Foundation Wildflower Hotline at 818-768-1802, ext. 7.

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The 2026 Green Thumb Awards granted by the National Garden Bureau (ngb.org) feature annual, perennial, shrub, and edible selections, each of which is in the “set-it-and-forget-it” category in terms of its resilience, ease of care, and length of productive season.

In the case of Cape Primrose Lady Slippers Double Blue Vein (Streptocarpus sp.), the bloom period is 365 days a year. Its gaudy purple flowers are double-tiered and are always present on a plant that grows one foot tall.

As for its care: “Little to no direct light is required for daily blooms. Keep evenly moist and feed just once every six months with water-soluble fertilizer.” Although this plant is promoted for indoor use, I have seen a lavender Streptocarpus thriving as a non-stop flowering ground cover in partial sun in Santa Monica and have witnessed a purple species (Streptocarpus saxorum) luxuriating on a sun-protected patio in a hanging basket in Corona Del Mar. So I imagine you could grow this species outdoors if you live in close proximity to the coast.

Fescue glow sticks (Fistula arundinacea), a clumping ornamental grass rising up to three feet with a spread of two feet, shows off golden yellow flower spikes for many months, beginning in the spring. They contrast perfectly with dark green foliage. Although preferring somewhat moist soil, Glow Sticks can withstand heat and some drought and are suitable for both sunny and shady exposures.

Azalea Encore Autumn Bliss displays its 3-4 inch semi-double flowers whose outer petals are soft pink to white and edged in pink, while its inner petals are pink as well. This is a robust bloomer whose flowers, with a unique crepe-paper texture, open continuously from spring until fall. This variety forms a symmetrical mound to a height of 3-4 feet.

Badabing! F1 tomato yields jumbo two-inch cherry tomatoes that are bright red, disease-resistant, and averse to cracking. The F1 designation means that the seeds of this variety come from tomatoes that are the hybrid of two different varieties. The seeds you find in Badabing!’s, if planted, will grow into plants with tomatoes of unpredictable characteristics. F1 is also meant to distinguish it from heirloom varieties, whose seeds become plants that yield a crop of the same quality as that of the tomatoes from which they came.

California native of the week: If you are searching for a selection for the margins of your pond or even for resting more submerged in the shallow end of it, I would recommend blue lavender rush (Juncus patens ‘Occidental Blue’). The astral appearance of its tubular foliage will mesmerize you. A most adaptable selection, this rush can grow in dry shade, too, and is hardy down to 15 degrees. It is tolerant of a wide variety of soil conditions, including clay, but can also grow under the canopy of an oak tree. Divide it in early fall or spring for propagation purposes. The genus name Juncus come the Latin verb iungere, meaning “to join” and refers to the use of its shoots for cords and ties.