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Many California native plants that are adapted or bred for urban landscapes have a reputation for being fussy with special needs, or being difficult to grow. California Poppy is the opposite. It requires little more than scattering seeds from fall through late winter or early spring in warm-winter California areas; and occasional watering, especially during warm-to-hot weather when grown as an annual, or in coarse or sandy soils.
California Poppy is among the very best options, native or otherwise, for lovely, resilient, and somewhat-drought-tolerant bedding flowers and mass plantings in temperate and mild-winter California areas. It becomes extremely drought-tolerant after establishing a thick taproot of several inches or longer, most reliably in cool areas, such as in California coastal areas and in mild temperate-climate areas with cool summers.
California Poppy thrives in almost any well-drained soil, and is a long-time reliable solution in Mediterranean climates for color on hillsides and in other difficult areas. It attracts and provides food for various native and non-native insects and pollinators. It can bloom almost year-round in mild-winter, mild-summer areas.
Cultural needs and environmental conditions: California Poppy needs full sun during cool-to-warm weather. It is perennial, but also grows as an annual in gardens and in wild areas where summer temperatures exceed about 90°F for long periods or where winter temperatures drop below about 15° to 20°F. It grows and blooms best at daytime temperatures of about 55° to 80°F. Established plants may die back or go dormant during summer heat.
Good drainage is essential for growing California Poppy. It prefers well-drained clay and loamy soils but tolerates and often thrives in poor or infertile soils provided that they drain well (such as clay soil on hillsides), and tolerates a wide range of soil pH from about 5.2 to 8.3, with an ideal pH of about 6.5 to 7.5. It may germinate poorly, underperform, and need more-frequent watering in coarse and sandy soils.
Many California native landscape plants don’t tolerate soil fertility, and suffer or die in the rich, microbially active soils needed for vegetable gardens. California Poppy is partially an exception; it makes a reasonable companion in garden borders that receive less water, or interplanted with established non-native plants in well-drained soils where watering is infrequent. While normally best kept to drier soils, it can be grown among or beside vegetables and perennials, especially in raised beds and soils that drain well. When grown in rich soils that remain constantly wet or moist, California Poppy tends to suffer from root rots and other diseases. It may produce more vegetative growth and fewer or no flowers in fertile soils, especially those that are high in nitrogen. See Soil and Microclimate Tips for California Poppy (Eschscholzia california) for more information.
Planning and preparation: California Poppy has two subspecies: 1) Eschscholzia californica californica, with the well-known yellow-orange blooms; and 2) Eschscholzia californica mexicana, or Mexican Gold Poppy, which blooms yellow, with a native range primarily in the Southwestern United States and Northwestern Mexico. Varieties are available in a range of colors, with mixes available including Confetti (orange, white, pink, red, and yellow single blooms); Mission Bells (rose, red, white, orange, and yellow double and semi-double ruffled blooms); and Spring Melody Blend (rose, red, white, orange, and yellow double and semi-double blooms). California Color Flower Mix includes California Poppy and many other native wildflowers.
The best planting season for California Poppy is fall through late winter or early spring in most of California. The winter growing season coincides with the least sunlight and shortest days. Be sure to plant California Poppy seeds in an area that will receive full sun throughout the winter. Consider planting multiple rounds of seeds for staggered germination and flowering, especially early or late in the season when California Poppy is vulnerable to heat and/or cold. Original and native strains may naturally germinate more variably and over a longer period, a helpful trait for the species’ survival in the wild, but which also tends to result in a variable or scattered blooming.
California Poppy plants may form dense mats or grow in more upright form. They normally grow from about several inches in height to about 12 or 14 inches tall, but under ideal conditions with ample spacing can grow to about 2 feet tall.
Germination and planting: California Poppy may be sold in nurseries as seedlings but dislikes roots disturbances and does not transplant well. Broadcast or sow seeds directly outdoors into moist, pre-irrgated soil or directly before fall/winter rainy periods.
Seeds can be scattered at the rate of one seed every 2-3 inches or about 20 seeds per square foot. Leave seeds at the soil surface undisturbed, or rake gently into soil. While counter-intuitive for many gardeners, it’s best not to cover California Poppy seeds with soil. Be cautious with irrigating seeds; hand watering or flooding may wash away seeds or move them to lower areas and channels. When irrigation or rainfall might be forceful enough to disturb or wash away seeds, cover with a thin layer of about 1/16-to-1/8-inch fine soil or sand.
Seeds germinate most reliably at cool-to-warm temperatures of about 60° to 70°F, and may take up to 30 days or longer to germinate at colder temperatures. Misting or watering once or twice daily may improve or speed germination. Seeds planted into coarse or sandy soils may need watering daily for optimal germination, especially during warm weather. Seedlings need sufficient moisture during the first few weeks after germination.
When planted densely or with vigorous germination, plants may remain smaller in a dense mat and often won’t reach maximum size or bloom optimally. Thin as seedlings or space seeds about 4-6 inches and thin as seedlings for final spacing of 8-12 inches between plants for optimal size and blooming.
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