Hello, first I'd like to tell you my situation.

I have two glass vases that each contain lucky bamboo in rocks with water. I have one with 5 stalks that is very healthy, and the other has 3. I've never moved them since I first placed them, and I've also never had to fertilize them. (mostly in fear of over fertilization!)

A few months after I put the 3 stalks in, one started to get moldy at the top. So I cut the plant just above one of the rings. It took about 3 months before it finally started sprouting again. While the stalk with no growth on it just sat in the water, the other two took off growing. The growth on top has grown probably the same size as the stalk itself.

For probably 6 - 8 months since then, all of them have been doing great.

Recently, I noticed that there is a brown spot, about the size of an adult's finger print, on the stalk that I had to cut with the mold. Also, just the tips of some of the leaves in that same vase are turning yellow. The other day I took the rocks out and cleaned them, and the vase, because I noticed algae had started to grow.

Like I mentioned before, I've never fertilized my plants, so if that may be a solution, what kind of fertilizer is best? I've heard that using aquatic plant food is good.

I am also worried that it may be getting too tall. I'd like to keep from cutting the main stalk, is there a way to trim just the foliage?

Thank you for your time reading my post, and hopefully you'll be able to provide me with some tips on bamboo care. It hurts to see my plant suffer!