Once in a while, a stray seed of a plant that would normally be considered to be an invasive exotic species happens to grow in a spot where it happens to fit. Those of us who regularly pull up unwanted feral seedlings, are typically skeptical. We probably pull up many such seedlings merely because we do not trust them, or because we do not want them broadcasting their seeds elsewhere in the neighborhood. In our region, Acacia dealbata, blue gum eucalyptus, black locust, pampas grass, broom, poke berry and Himalayan blackberry get no consideration; and their seedlings should be removed as promptly as they are discovered. English ivy does not get much more consideration, but every once in a while, it happens to wander into a situation where it is allowed to stay.
Catalpa is one that we are not quite sure about. It is an exotic species that happens to disperse unwanted seed at times, but is not invasive enough to warrant prompt removal of all seedlings. Many seedlings appeared in the area several years ago, and most were removed because of where they were. However, if any other seedlings have appeared since then, they have been discreet enough to remain unnoticed. It was as if there was a very specific mating season. Catalpa had not been invasive prior to that, and has not been invasive since.
Two of the feral catalpa seedlings appeared on the edge of the parking lot at the Felton Presbyterian Church. One became disfigured and distressed, and finally died before being removed. The other just happened to be in the middle of a parkstrip, and in a location where a good sized shade tree had room to grow. Because no one could find a good reason for removal, it stayed. After only a few years, it is now a good sized and very well structured shade tree that blooms nicely this time of year. It may not last long, since catalpas are short lived, but for now, it is a nice component to the landscape. This weed gets a happy ending.
Weeds always seem to have unfair advantages. While we pamper so many of our desirable plants to get them to grow and perform, weeds proliferate without help. They survive harsh conditions, inferior soil and some of the techniques we try to kill them with. They do not need much, if any water. They broadcast inordinate volumes of seed. They grow fast enough to overwhelm other plants.
This is the time of year when most weeds really get going. Like most other plants, they like the warming weather and moist soil of early spring. Many bloom and sow seed before summer weather gets too warm and dry in areas that do not get watered. Some that happen to be where they get watered may perpetuate second or third generations through summer! Weeds really are efficient!
However, the same pleasant weather that allows weeds to grow so efficiently also allows us to come out to work in the garden. The same soft rain moistened soil that the weeds enjoy so much also facilitates weeding. It will be more difficult to pull weeds later when the soil is drier, and roots are more dispersed. It is best to pull them before they sow seed for the next generation anyway.
Most of the annoying weeds are annuals or biennials. Some are perennials. A few weeds might be seedlings of substantial vines, shrubs or trees, like privet, acacia, eucalyptus or cane berries, especially the common and very nasty Himalayan blackberry. Cane berries have thorny stems that are unpleasant to handle, and perennial roots that must be dug. They can be very difficult to kill.
Tree and shrub seedlings should be pulled or dug out completely. Except for palms, most regenerate if merely cut above ground, and are very difficult to remove or kill the second time around. It is no coincidence that they tend to appear in the worst situations under utility cables and next to fences and other landscape features. Birds tend to perch in such spots as they eat the fruit from around large seeds that then get discarded, or as they deposit small seeds that were within small fruit and berries that they ate earlier.