Offsets are miniature versions of the plant, which have few roots of their own initially. Roots usually develop towards the end of the growing season and have to be encouraged by severing the connecting stems from the parent.
The term offset is also used to describe young bulbs and shoots that grow from the roots of plants such as cordylines and yuccas. These can be removed by carefully scraping away soil at the base of the plant and cutting off the offset with a sharp knife, preferably with a section of root attached.
Most offsets can be removed in their first year, but some, such as yuccas, grow slowly and should only be separated when they are a few years old.