Mary...do you know what variety of Equisetum you have? I ask, because different varieties have different growing requirements (some need to be in water, and some need more sun than others).

I'd also suggest posting your question on the Herb Forum (it's an herb) and on the Houseplant Forum.

In the garden, most Equisetum are extremely invasive, and the primary problem is getting rid of it.

Unless you have lots of light in your bathroom, I would guess that may be part of the problem. Also, lack of humidity is hard on many plants. The common Equi. are full sun plants.

We have a park here where Horsetail is fully shaded and growing like it is on steroids. Color - a muted kelly green.

Soil moisture - damp w/ "moss" growing randomly all over.

Go firgure.

Jake