In my years of gardening, I have encountered some audacious charmers. It was usually love at first sight, but looks can be so deceiving. When I tried to tame these beautiful bullies that were no longer welcome in my garden, months of hard labor ensued. Here are my experiences with some of them.

	Sea holly in bloom

An Ideal Garden Plant?
Anyone who has seen a sea holly (Eryngium spp.) in full bloom would likely agree that the ball-like flowers with spiny bracts are a splendid sight. They provide a structural element to a border and make attractive dried flowers. They also have remarkable drought, salt and neglect tolerance and are mostly insusceptible to pests and diseases. Their only requirement is full sun. In other words, they're practically an ideal garden plant. I thought so and bought a half dozen. In hindsight, I should have bought six fewer.

During their first summer, the sea hollies behaved well enough, remaining where they had been planted. The long-lasting flowers were the stars of my border for many weeks. However, they self-seeded liberally and the following spring, my garden was covered with sprouting sea hollies. Adding to the chaos were the numerous plantlets produced at the bases of the mother plants. After deadheading well before they dropped their seeds and removing all new unwanted growth, I thought I had the invasion under control. I was wrong; the next year I had even more sea hollies. The bold plant was determined to stay and had colonized my garden as well as the lawn. Its secret weapon was its long, strong taproot. As with dandelions, if even a tiny piece of root is left in the soil it will produce a new plant. Three years later, I'm still pulling the odd one. If you like this plant, I suggest you grow sterile hybrids only, such as 'Sapphire Blue' or 'Sunny Jackpot.'