Volunteers, or self-seeders, can be a welcome addition to the summer garden; but, sometimes, we just want a particular annual for one season. If that’s the case, here is my short list of unusually persistent annuals that you may want to limit to patio pots rather than incorporating them into your garden border:
Lobelia siphilitica (Great Blue Lobelia)
Nicotiana alata (Flowering Tobacco)
Each of these is easy to grow from seed once the soil has warmed up, and each has an uncanny ability to survive for 3-4 years until popping up again as a seedling in the most unexpected places. If you’re trying to establish a wildflower meadow with reliable re-seeders, these are the plants for you. Otherwise, be aware that these seeds can travel long distances on a windy day.
If you have had experience with any aggressive annuals other than these three, feel free to comment.