The oxalis is as bad as mentioned. I live near the coast in Ca. and just the moist air is enough to keep it happy. The most important thing is to keep an eye open to spot it early in containers so it can be removed before it gets established. Round up in a strong mix works and if no plants are near it, its easy then. Use a plastic bottle with a mister, covering the plant first. Placing poted plants on a higher plane than the established oxalis helps too. Most of all do not let it seed or you are in for it. Make sure when you buy nursery stock that there are no oxalis plants in it too. You realy do not want to bring any more home if possible.