ChiloquinNews article 9/12/2011
Almost all plants produce seeds as a way to increase their numbers, their variability and their range, but in many cases those seeds do not germinate easily, or require special conditions, like a fire, before they sprout. This ensures that an area will not be overrun and gives those seeds that do germinate the chance to develop without heavy competition for nutrients and water.
However, some plants are prolific re-seeders. Mostly it’s the annuals, or biennials. The seeds will germinate, grow, produce flowers then fruit and seeds, and finally die, all in the space of one or two summers. Since life is so short for them, they produce millions of seeds to ensure the survival of the species, and often, the seeds can lie dormant in the soil for many years.
This becomes very evident to the gardener when weed seeds continue to grow long after the gardener thinks she has eradicated that particular plant. Every time the soil is disturbed another few of those seeds resurface, ready to germinate the following spring, and of course, every plant that escapes detection releases another host of seeds or they blow in from neighboring properties. Their numbers can be reduced by the tedious removal of the flowers before they can form seeds, and by crowding them out with seeds from other plants that we would rather have. This is the time of year when I look with despair on all those seed heads that I have not managed to remove in time.
Surprisingly, it is not always easy to get plants going from seeds. Very often we put out seeds for a couple of years and nothing happens, until finally we get a couple of plants going, and then before we know it, the plant has taken over and spreads itself far and wide. And very often, it is not where we want the seed to grow that it grows. Last fall I spread Shirley poppy seeds in an area where I wanted some color, but did any seeds germinate there? No, they germinated all around the edge of that area in the gravel driveway, rather than in the rich garden soil. Very often, if we are spreading seeds and they are not growing, it’s because we don’t really know what conditions the seeds need, and finally, just by blind chance we put a couple where they can grow, and nature takes over from there.
There are some lovely flowers that will reseed prolifically given the right conditions. Those doing well in my garden are Shirley poppies, Black-eyed Susans, Feverfew, Rose Campion, Scarlet Gilia, Knautia, Clary Sage and Muhly grass. I have noticed California poppies doing well in other gardens but I have not found the right spot for them yet.
There are two re-seeders, Bachelor Buttons and Oxeye Daisy, that are lovely to look at, but so aggressive that they have escaped into the wild where they are crowding out native plants. I have tried to eliminate both from my garden just because of this, but like thistles, they are hard to remove entirely. In many gardens they are encouraged because they do, in fact, grow under conditions where not much else will. Whenever you see a plant that grows along the roadside, think several times before you encourage it in your garden, even if it does have a pretty face.
Muhly grass and Knautia (left) and Rose Campion (right), all self-seeded in my garden.