A centennial approaches for California’s State Flower (although the California Floral Society first proposed it in 1890), which means more attention for Eschscholzia californica. That is good. It also means that many people, with good intentions, will plant California poppies. That is not necessarily good, if those poppies are planted in an area where California poppies already grow.
Plants living in an enviroment over many generations become adapted to the specific environment—those plants that have features that suit them to the habitat are more likely to survive than those that don’t, and these plants are the parents of subsequent generations. Where California poppies grow naturally, they are “fine-tuned” to their environment.
When we plant California poppies in these areas, they ordinarily breed with the poppies that are already living there. Cultivated varieties of California poppies are not as suited to the local environment as the local plants already are—in fact, some of them are best suited to gardens in England, where many of the cultivated forms were first developed. (Cultivated poppies also lack seed dormancy, and will germinate even when there isn’t enough rain to see them through to flowering.) If we add only a few poppies, they may die before reproducing, or their offspring may be less fit, so that after a while their genetic contribution is gone. If we add a lot, though, relative to the number of poppies already living there, the newcomers can "genetically swamp" the local plants: most of the new generation will be newcomer × newcomer or newcomer × local, with very few local × local offspring. If the newly planted poppies are not as suited to the environment, this can result in the entire population at that site being lost. This is especially a problem when the introduced poppies spread in “good” years, but then a “bad” year comes along and there are no well-adapted plants left to survive.
So planting poppies in the wrong place can actually reduce, rather than increase, the acreage of our State Flower.
Where should you plant poppies, then? Gardens, vacant lots, and even lawns in urban and suburban areas are good places—native poppies almost never do well in these habitats, and most native poppy populations are destroyed by urbanization. Freeway margins in urban areas are also good places. Heavily impacted agricultural areas, such as the San Joaquin and Imperial valleys, also provide habitats along roadsides and in waste places. Considering how much of California is urbanized or in intense agriculture, this provides a lot of area for poppy plantings.
But when it comes to rangeland, natural areas, foothills, mountains, and coastlines, either plant locally collected seed or don’t plant at all. Don’t love our State Flower to death.