Question
Dear Mr. Simpson,

About a year ago, I went to a cactus farm and bought a barrel cactus 14 inches in diameter.  The thorns at the top were very short and the overall shape of it was very round and symmetrical.  I've tried to take care of it the best I could but now, the thorns on top (near the soft wooly part) are very long and the cactus hasn't grown in width but only height.  Also, its not perfectly round anymore - it's almosed lop-sided.  I recently bought a new on which is "16.  What can I do so it will keep its appearance and shape, and how do I keep the thorns on top short?  I want mine to look like the one at this link:    http://ourworld.compuserve.com/homepages/davidtraish/images/Echinocactus_grusoni...

Sincerely,
Fred

Answer
Fred,

Without seeing a picture of your plant, I am guessing. However, it sounds like your plant is suffering from a lack of light. Typically, when a cactus is subjected to low light, the start to grow very spindly. In the case of a barrel cactus, you have described what happens in those conditions.

Make sure your plant gets the brightest light possible, even direct sun as long as it was grow in direct sun. Also, make sure you orient it properly (north/south) so it doesn't sunburn. If your plant is indoors, you will need to supplement with grow lights for as many as 15 hours per day. Hope this helps.

Sincerely,

Greg