Sowing California Native Wildflower Seed With the First Fall Rains

Aug 18

Sow California native wildflower seed in Santa Cruz County between late October and late November, timed to the first soaking rains. According to UC Master Gardeners of San Mateo and San Francisco Counties, late October through late November is the ideal window because it mimics how native annuals seed themselves in the wild and lets the winter rainy season handle the watering.

That single decision, sowing in fall instead of spring, is the difference between a patch of wildflowers that mostly takes care of itself and one you end up hand watering through May. Our natives evolved around a wet winter and a dry summer, and working with that rhythm costs less water and less time than fighting it.

Why Does Fall Sowing Beat Spring Sowing in Coastal California?

California annual wildflowers run on a schedule that has nothing to do with the national gardening calendar. UC Master Gardeners of Butte County describe the cycle plainly: seeds germinate with the fall and winter rains, roots and lower leaves grow through the cool months, plants bloom in early spring, and seed matures from late spring through summer before the parent plant dies.

The winter rains do your irrigation. Seedlings that come up in November spend four or five months building root systems while the soil stays damp, so by the time our dry season arrives those roots are deep enough to finish flowering on stored soil moisture.

The cool, damp season is also what the seed is waiting for. Calscape, the California Native Plant Society's native plant database, notes that baby blue eyes sown outdoors in late fall may do well with no treatment at all, and gives 59 degrees as its germination temperature. Lacy phacelia is the same story: sow outdoors in late fall, or germinate it indoors at 59 to 70 degrees. Spring-sown seed hits rising temperatures and drying soil at the wrong moment.

Spring sowing is possible, but it is a different job. UC Master Gardeners of Contra Costa County note that you can keep sowing through March, with November through January being optimal because it requires the least supplemental water. Anything sown late will most likely need hand watering to hold a bloom once the rains stop. If you have wondered whether the fall planting advice applies to more than shrubs and trees, see our guide to whether fall is actually the best time to plant in California.

When Exactly Should You Sow in Santa Cruz County?

Watch the forecast, not the calendar. The target is the first storm that wets the soil several inches deep, which on the Central Coast usually lands between mid-October and Thanksgiving. Some years it comes early. Some years it does not arrive until December.

A practical sequence for our county:

Late September through mid-October. Prep the seedbed and run the weed flush described below. This is the part most people skip, and the part that decides how the patch looks in March.

Late October through November. Sow, ideally in the two or three days before a forecast storm. Rain settles seed into contact with the soil far more gently than a hose does.

December through February. Sow a second and third round for a longer bloom or to replace what birds took. UC Master Gardeners of Contra Costa County recommend staggering from mid-November through February and even into March, and note that staggered sowing also fills gaps where germination was thin.

Microclimate matters here. In the Santa Cruz fog belt and up in the mountains around Boulder Creek and Ben Lomond, soils stay cool and damp longer, and germination can be slower but more forgiving. Down in the Pajaro Valley and the warmer inland pockets around Scotts Valley, the soil dries faster between storms, so sowing right before rain matters more. If the season turns dry after you sow, water the surface rather than letting the seedbed bake. UC Master Gardeners of San Mateo and San Francisco Counties advise using a fine mist so you do not wash the seed out of place.

Which Native Wildflowers Should You Sow in Santa Cruz County?

These are species with documented California ranges and reliable garden behavior. Every description below comes from Calscape, the California Native Plant Society's plant database, which draws its distribution data from the Consortium of California Herbaria and Calflora.

California Poppy (Eschscholzia californica)

The state flower, and the one nearly everyone starts with. Calscape describes it as growing one to two feet tall with feathery blue-green foliage and flowers ranging from yellow to bright orange, appearing primarily in spring. Petals may stay closed on cloudy days, which is worth knowing if you garden in the fog belt and wonder why your poppies look shut all morning.

Calscape lists it as both an annual and a perennial herb, and notes it can be perennial in milder areas, which includes much of coastal Santa Cruz County. It self-seeds freely, tolerates poor soil including clay, and is deer resistant, though rabbits may browse the leaves. For a full local growing guide, see Growing California Poppies in Santa Cruz County.

Tidy Tips (Layia platyglossa)

A sunflower-family annual with a flower head about two inches across. Calscape describes 5 to 18 outer ray flowers that are bright golden yellow with distinct, sharp-margined white tips, surrounding numerous yellow-orange disk flowers. It grows 6 to 24 inches tall and is native to low-elevation dry habitats in the Coast Ranges, which includes us. It prefers clay or loamy soil, tolerates sand, and Calscape notes it wants somewhat more water than some other wildflowers, so give it the damper end of a slope rather than the driest corner.

Baby Blue Eyes (Nemophila menziesii)

Low and spreading, roughly six inches tall and six inches wide, with bright blue flowers in spring. It handles full sun or partial shade, which makes it useful for the half-shaded edges most Santa Cruz gardens have. One detail worth knowing before you order seed: Calscape notes that three varieties are recognized, and that var. atomaria, found on the north coast, has almost pure white flowers. If you are picturing blue and receive white, the seed was not mislabeled.

Globe Gilia (Gilia capitata)

Distinctive enough that it reads as intentional in a garden bed. Calscape describes spherical flower clusters of 50 to 100 small flowers held atop branching stems, with individual flowers ranging from white to pink, lavender, or light blue. Height varies widely, from about 4 to 36 inches, and Calscape notes eight recognized subspecies, so expect variation. It is widespread in California including along the coast, coastal prairie is among its listed plant communities, and Calscape says no seed treatment is required, though about two weeks of stratification improves germination.

Farewell to Spring (Clarkia amoena)

A two to three foot annual that flowers in shades of pink to purple in late spring and early summer, exactly when the poppies and tidy tips are winding down. Calscape lists coastal prairie and northern coastal scrub among its habitats, so it belongs here. It tolerates sandy and clay soils, needs minimal water once established, and Calscape recommends sowing it in masses or drifts rather than scattering it thin.

Elegant Clarkia (Clarkia unguiculata)

The shade-tolerant clarkia, and endemic to California. Calscape describes tall thin stems to about three feet, narrow leaves, and four spade-shaped petals in various shades of pink, blooming in summer when many wildflowers have finished. Its natural habitat is open woodlands, usually oak woodland or mixed evergreen forest, and Calscape lists it as tolerating full sun through deep shade. For gardens under oaks or on the shaded side of a Santa Cruz Mountains property, this is one of the few wildflowers that genuinely performs.

Lupines (Lupinus nanus and Lupinus succulentus)

Two annual lupines worth separating.

Sky lupine (Lupinus nanus) is the smaller one, 4 to 24 inches tall, with blue to lavender flowers in winter and spring. Calscape notes it is most common in California's Coast Ranges and Sierra foothills, and lists coastal prairie and northern coastal scrub among its communities. That makes it the better local fit.

Arroyo lupine (Lupinus succulentus) is larger, two to four feet tall, with spikes of purple-blue flowers that are sometimes light purple, pink, or white. Calscape calls it the most water-tolerant of all lupines and says it prefers moist clay or heavy soils, which suits the heavier ground in parts of the county. Calscape gives two different sowing depths for it, a quarter inch in the plant description and an eighth of an inch in the propagation notes, so anywhere in that range is defensible. One caution from Calscape: the seeds, leaves, and stems are toxic, so keep it out of reach if you garden with small children or nibbling dogs.

Lupine seed is the exception to the surface-sowing rule in more ways than one. UC Master Gardeners of Contra Costa County note that lupine needs special handling such as scarification or soaking before sowing. Calscape is more specific and differs by species: for arroyo lupine it recommends hot water or scarification and gives a germination time of 15 to 75 days, while for sky lupine it says fresh seed needs no treatment and only stored seed benefits. If your seed is fresh from a native seed source, sow some untreated and some soaked and see which does better. See California Lupine: A Wildflower That Feeds Your Soil for the nitrogen-fixing side of these plants.

Phacelia: Read the Species Name

This is where seed labels get slippery. Lacy phacelia (Phacelia tanacetifolia) is the one most seed racks carry, and it is a genuine bee magnet. Calscape describes lavender-blue bell-shaped flowers with long protruding stamens, held in clusters atop stems two to four feet tall, above deeply cut lacy foliage. It is widely used as a bee-friendly cover crop in vineyards and on organic farms. Two cautions: Calscape notes some people get skin irritation from touching the plant, and its listed habitats are sandy and gravelly slopes and open places in chaparral or woodland, not our coastal terraces.

The phacelia suited to coastal bluffs is California phacelia (Phacelia californica). Calscape describes it as native to coastal northern California and Oregon, growing in chaparral, woodland, coastal bluffs, and grassland, with dense one-sided coiling clusters of small white to pale blue or lavender flowers. It runs six to 18 inches tall and feeds the endangered Mission blue butterfly. Note that Calscape lists it as both an annual and a perennial herb, so unlike the rest of this list it can persist past one season.

Both are Californian. Only one is local. Choose deliberately rather than grabbing whichever packet says phacelia.

How Do You Prepare a Seedbed for Native Wildflowers?

The single biggest predictor of success is how few weed seeds are sitting in the top inch of your soil in November.

Run a weed flush first. UC Master Gardeners of Contra Costa County describe the technique: water the area now to trick weed seeds into germinating, then hoe the seedlings down as they appear. Repeat if you have time. Every weed you kill in October is one that is not competing with a two-inch wildflower seedling in January.

Do not dig deep. The same UC source is specific: when you are ready to sow, do not turn the soil deeply, because that unearths buried weed seed. Their rule of thumb is to never hoe or till more than four inches down.

Skip the herbicides. UC Master Gardeners of San Mateo and San Francisco Counties warn that herbicides are likely to affect the seedlings. For weedy lawn or compacted ground, they recommend sheet mulching well in advance instead.

Do not amend heavily. UC Master Gardeners of San Mateo and San Francisco Counties note that natives prefer well-drained soil, typically without fertilizer, and that soil amendments are not necessary, though organic green compost can be added. UC Master Gardeners of Butte County say the same thing more simply: you do not need to add any amendments. Rich, fertilized soil grows tall floppy wildflowers and very happy weeds.

Deal with existing mulch. If your bed is under deep bark or large wood chips, clear a space down to soil. UC Master Gardeners of San Mateo and San Francisco Counties put the limit at about an inch, and say to remove thicker mulch to improve germination.

Take photos of your weeds. UC Master Gardeners of San Mateo and San Francisco Counties suggest photographing your germinating weeds during the flush, because weed seedlings and wildflower seedlings can look very similar in January. UC Master Gardeners of Butte County suggest the same trick in reverse: sow a few seeds in a labeled pot and use the sprouts as your reference.

What Is the Right Way to Sow the Seed?

Small seed, shallow sowing, good contact with soil.

Moisten the soil first. Water the surface before you sow, sow, then mist again. Seed that sits dry after sowing is seed that does not germinate.

Mix seed with sand. UC Master Gardeners of both San Mateo and San Francisco Counties and Contra Costa County recommend combining one part seed to three parts coarse or horticultural sand and broadcasting the mixture. The sand spreads tiny seed evenly and helps cover and protect it.

Sow shallow, then tamp. Contra Costa recommends about one eighth of an inch below the surface. San Mateo and San Francisco advise covering very lightly with less than a quarter inch, noting that deeper burial impairs germination, then tamping lightly to protect seed from wind and birds. If you rake after scattering, keep it shallow.

There is a real disagreement worth naming. Calscape's guidance for California poppy says not to cover the seeds with soil or mulch at all, and to simply scatter them and let the rains water them in. UC's general wildflower guidance says to cover very lightly. Both approaches produce poppies. For a mixed patch, follow the UC guidance of a very light cover, since some species in the mix will want it. For poppies alone on bare ground before rain, scattering uncovered works.

Flag the area. Mark where you sowed. In January, a bare-looking patch is very easy to walk on, weed by mistake, or decide to plant something else in.

How Do You Keep Birds From Eating the Seed?

Birds are the most common reason a fall sowing comes up patchy, and the fixes are simple.

Mixing seed with sand hides it and partly covers it. Tamping lightly after sowing presses seed into the soil surface where it is harder to spot. A single thin layer of light mulch also works, and UC Master Gardeners of Contra Costa County note that it protects from bird predation while keeping soil moist, as long as it stays thin enough not to smother the seed or block water. For heavier pressure, the same UC source recommends bird netting or a floating row cover instead of mulch. Remove it once the seedlings are up and established so the plants get airflow and light.

The other answer is quantity and timing. Sow a bit more than you think you need, and plan on a second sowing in December or January. UC Master Gardeners of Contra Costa County list "your first flush of seedlings is eaten by birds" as one of the standard reasons to stagger sowings, which tells you how normal it is.

What Should You Avoid? Start With Generic Wildflower Mixes

Most cans and shaker bottles of wildflower seed sold in California are not California wildflowers.

UC Master Gardeners of San Mateo and San Francisco Counties put it directly: some wildflower mixes have flowers that are not California wildflowers and may even include flowers that are invasive to California, and you should be sure the mix is labeled as containing only California wildflowers. That is the whole test. Turn the package over and read the species list. If the label will not tell you what is inside, that is your answer.

The problem is not only aesthetic. A mix that seeds a non-native annual into a Santa Cruz County garden puts that plant next to open space, and coastal grassland and scrub around here are already under pressure from introduced annuals.

Two other things to avoid.

Do not fertilize the patch. Native annuals evolved on lean California soils. Fertility mostly benefits the weeds and makes lupines and clarkias flop.

Do not sow into deep mulch or unweeded ground and hope. The seed will germinate, then lose to weeds it cannot outgrow. Preparation is most of this job.

If you are not sure where to buy seed with a full species list, our guide to where to buy seeds for your California garden covers regional sources, and California native plant nurseries worth the drive from Santa Cruz lists the specialty nurseries that stock local-provenance seed.

What Should You Expect in the First Year?

Knowing what the first season actually looks like saves a lot of disappointment in March.

Germination will be uneven. Some species come up in two weeks, some take much longer. Calscape gives arroyo lupine a range of 15 to 75 days. A patch that looks half empty in December can fill in by February.

You will weed. UC Master Gardeners of Butte County are blunt: weed seeds remaining in the ground will germinate alongside your wildflowers and can overrun them if left unchecked. Plan on a few passes between December and February, with your weed reference photos in hand.

Bloom comes in waves, not all at once. UC Master Gardeners of Contra Costa County give the pattern: poppies and tidy tips are the early ones, clarkia and globe gilia the late ones. Sky lupine and baby blue eyes fall in between. This is why the same UC source suggests deliberately mixing early and late bloomers.

It gets ugly at the end. UC Master Gardeners of Butte County note that very large wildflower patches are a little less appealing once the plants dry up, and are also harder to keep weed-free, though that gets easier with time. Their recommendation is a good one: keep the patch small, or interplant herbaceous perennials and small shrubs that hold interest after the annuals are spent. Our guide to native plants for pollinators in Santa Cruz County covers perennials that pair well.

Year two is usually better than year one. These species self-seed. Calscape notes California poppy reseeds freely, and describes sky lupine, elegant clarkia, and farewell to spring as self-sowing annuals. Let the plants dry and drop seed before you cut them back, and the patch largely reloads itself.

Want a printable version of the fall sowing window and species list to keep in the shed? Grab the free planting resources in Your Garden Toolkit.

Frequently Asked Questions

When should I sow California native wildflower seed in Santa Cruz County?

Sow between late October and late November, timed to the first soaking rain of the season. UC Master Gardeners of San Mateo and San Francisco Counties identify late October through late November as ideal because it mimics natural seed dispersal and uses the winter rainy season for irrigation. Sowing can continue through February or March, though UC Master Gardeners of Contra Costa County note that November through January is optimal and requires the least supplemental water.

How deep should I plant native wildflower seed?

Very shallow. UC Master Gardeners of Contra Costa County recommend sowing about one eighth of an inch below the soil surface, and UC Master Gardeners of San Mateo and San Francisco Counties advise covering with less than a quarter inch of soil, noting that deeper burial impairs germination. Calscape gives arroyo lupine a slightly deeper range, an eighth to a quarter inch. Mixing seed with three parts coarse sand helps distribute and lightly cover it.

Do I need to water native wildflower seed after sowing?

Yes, at first, and then only during dry spells. Moisten the soil before sowing and mist again afterward, then let the winter rains take over. UC Master Gardeners of San Mateo and San Francisco Counties advise watering with a fine mist to keep soil moist during dry stretches without displacing seed, and note that in general it is better to underwater a native than to overwater it.

Are wildflower seed mixes from garden centers safe to plant in California?

Not automatically. UC Master Gardeners of San Mateo and San Francisco Counties warn that some wildflower mixes contain flowers that are not California wildflowers and may even include species that are invasive in California, and advise buying only mixes labeled as containing only California wildflowers. Read the species list on the back of the package before buying. If the package does not list species, choose a different product.

Does lupine seed need to be soaked or scarified before sowing?

It depends on the species and the age of the seed. UC Master Gardeners of Contra Costa County note that lupine generally needs scarification or soaking. Calscape adds species-level detail: arroyo lupine (Lupinus succulentus) benefits from hot water or scarification, while sky lupine (Lupinus nanus) needs no treatment when the seed is fresh and only benefits from scarification when stored. When in doubt, sow half treated and half untreated.

Which native wildflowers grow in shade in the Santa Cruz Mountains?

Elegant clarkia (Clarkia unguiculata) is the strongest candidate. Calscape describes its natural habitat as open woodlands, usually oak woodland or mixed evergreen forest, and lists it as tolerating full sun, partial shade, and deep shade. Purple Chinese houses (Collinsia heterophylla) is another option, described by Calscape as preferring part shade with a moist site and reaching about 12 to 18 inches with lilac to purple flowers.

Sources

Adrienne Gaughan