While no one was looking, I pulled a few pieces of English daisy from a weedy lawn at a job site and put them into my pocket. No one would have cared, since they are considered to be aggressive lawn weeds anyway. I took them home and potted them, and they are now doing quite well; actually, too well. Now, I am seriously doubting that I want to plant them in my own garden.

Typical English daisies look innocent enough as compact perennials in refined landscapes. They actually seem rather puny since they individually get only a few inches tall and wide, with red, pink and a few white flowers. However, they have a potentially bad habit of naturalizing in areas where they are particularly happy. The first generation of seedlings is not quite as plump or as colorful as the parents are, with more white flowers than pink and red. After only a few generations, naturalized English daisy reverts to lower and more aggressively spreading plants with simpler white flowers.

English daisy would be nice naturalized around my home, but I am afraid that it would not stop there. It might have the potential to spread away from my garden, and even into the creek, where it could be transported downstream. Similar concerns have prevented me from planting other potentially invasive plants like (non-native) violets, honeysuckle, and English and Algerian ivies.

After all, pampas grass, periwinkle, Bailey acacia and Scotch broom were once planted as ornamentals in gardens before becoming naturalized and remarkably aggressive weeds throughout vast areas. Japanese honeysuckle does not seem to be invasive locally, but has hybridized with native honeysuckle species, ruining the original genetic properties.

Of course, different plants have the potential to become aggressive naturalized weeds in different areas. In Oklahoma, the silk tree has naturalized. Cajeput trees are overrunning the Everglades of Florida. Black locust and tree of Heaven have become invasive in the Sierra Nevada, and many other places in North America.

Invasiveness can be a problem in both rural areas and urban areas. In rural or forested areas, invasive plants can escape into the surrounding area where they can become impossible to control, and can be devastating to the natural ecosystem. Although not likely to be as threatening in urban areas, invasive plants can cause serious problems for neighbors who do not like them. For example, Algerian ivy that might be a useful and controlled ground cover in one garden can get into and overwhelm a neighboring garden, and crush the fence in between.

The potential for invasiveness again reminds us the importance of identifying the ‘right plant for the right application’. If it is likely to force its way into the neighbor’s garden, and the neighbor does not like it, it is not the right plant. Even if the neighbors like it, the potential damage to fences and other structures needs to be considered.

Remember where invasive plants come from. Some are from harsh climates where they need to proliferate abundantly just to get a few of their next generation to survive. Others are from crowded forests and jungles where they need to compete aggressively with other plants. Their behavior that gives them an advantage at home may not be so acceptable in the garden.

Contact Tony Tomeo or look for specialized gardening information and previous columns at www.AskTonyTheGardener.com