Make sure the container does not have holes. It will grow out of the container and into the ground via holes. This plant has been around for millions of years. It's a survivor. I noticed Sunday that the Equisetum growing by the newish glass conservatory at the Huntington has begun to come up on the other side of the sidewalk. You would think they would have known better.

Howdy, folks! I posted this over on the Bog Forum....but thought there might be some interest here, too. I've been watering every two days during the heat, and fertilizing just about once a month. My container is brimming full, with spore-cones a' plenty. Pics from May, June, and July. May: June: July: And why not? A bonus shot: Josh

Reading through some of the other discussions here, it would seem that this stuff is extremely hard to control once it escapes. One person said it goes as far as 36" deep, so 4" is not gonna cut it. I would recommend that the only way to truly control it is with a closed bottom barrier. Even a small drainage hoLe in a pot is enough for it to escape. A large, closed bottom terra cotta pot buried with the top inch or so above ground seems like a good bet. DO NOT LET IT GROW FREE IN THE GROUND OR YOU WILL LIKELY REGRET IT!

Hi there. Thanks for your comment! I do keep them moist and they're in a southern window so they get lots of direct light. After talking to some more experienced gardeners, I think the most likely problem is that they're root bound. I'm going to use an auger to dig holes in the soil and fill them with fresh soil and see if that helps