I have a castor plant. It has very woody stems. Can I cut it down, and if so, will it leaf up and fill out again?

It depends where you live. In cold areas they are pretty much annuals and will die at the end of the growing season. At the other end of the heat range, it will grow back if you cut it down. However, you should be very careful in having this around if you have children around the garden - the seeds are the source of the deadly poison ricin, and also the castor oil that is such a good remedy for constipation in small doses. Altogether a dangerous plant to have around. Derek