California poppies grow best in USDA zones 9 - 11, the dry western regions of the US. They are easy to care for and do well in infertile soil. Purple poppy mallow is another variety that grows best in infertile soil, but this one grows best in zones 4 through 8. Corn poppies, on the other hand, need rich, fertile, wet soil to grow well. Celandine poppies are woodland flowers that grow best in the east, zones 4 through 8. Go to http://planthardiness. ars. usda. gov/PHZMWeb/, type your zip code in, and press the red “find” button to figure out what zone you’re in.
If you have a variety that does well in infertile soil, you’re in luck - you don’t have to add anything to your soil to get it ready. Many poppies grow perfectly well in rocky terrain that doesn’t support other types of flowers as well. For varieties that require rich soil, till the soil and mix in rich compost or bone meal to add the nutrients your poppies need to thrive.
Water your poppies moderately and regularly when they’re in bloom or are almost in bloom. After the flowering period, only water your poppies when the top inch of soil is dry to the touch. [5] X Research source
