California poppies are best propagated from seed. Although they can be propagated through transplantation, it is hard to do, and often times the plants do not survive the process. If you must start indoors, use deep pots. Sow seeds in the early spring once the ground reaches 60 degrees Fahrenheit and is workable. Choose an area that receives full sun, at least six hours of sunlight, and has well-draining poor soils. Mix the seeds with 4 parts sand to ensure even spacing. Cover the seeds with 1/16 inch of soil. Water immediately after sowing and keep the soil moist until the seedlings develop their first leaves.
Reduce watering of California poppies once they become established. Water plants one or two times per week only during periods of no rainfall. They are highly drought-tolerant and will suffer if kept too moist. Problems such as powdery mildew or mold will form on the plants' leaves if excessive watering is prolonged. Their roots will begin to rot and die back, affecting the health of the plant. If rainfall occurs, do not provide additional water.
California poppies prefer poor soils. If sown in areas where the soil is too rich and fertile, the poppies will produce foliage with few flowers. Fertilize California poppies only when they appear to be unhealthy with yellow leaves. Apply a 10-10-10 nitrogen, phosphorous and potassium fertilizer at the recommended rate on the label. Do not fertilize California poppies under any other circumstance, as excess fertilization will stop blooming and can harm the plants.
Blooms will begin to appear on your poppies one and a half to two months after sowing. Normal bloom time lasts for six to eight weeks. Pinch blooms from their stems as they begin to fade to encourage new blooms to form. This practice can prolong the blooming period of California poppies by one to two additional weeks.
Leave a few of the last blooms on the stems in order to encourage seed production. The petals will drop leaving a seed head behind. Remove the seed head from the stem once dry in zones 1 through 4. Store the harvested seed heads in glass jars or paper envelopes in a dark, dry and cool spot until spring sowing. Allow the dried seed heads to remain on the stems in zones 5 through 9. In these zones, the California poppies will self-sow their seeds.
Seedman Basic Info:
A Classic Heirloom Favorite. Grows about 12 inches tall. Easy to grow, plant them directly in your garden and they will spread easily!
Sow on cultivated soil. Can be fall planted in California, but should be Spring planted in cooler zones. Plants are easy to grow, but do not like to be transplanted. Sow in place when possible. Prefers sunny spot with well drained soil.