Brian, Most of my experience is with tuberous species rather than hybrids. Almost all my repotting and dividing is done when plants are in early active growth or just before waking from dormancy. This way roots can be checked and signs of rot can be detected, and they can be watered in and monitored for response. It's perfectly ok to divide your pots now but I recommend tearing the plants apart rather than cutting. A lot of the fine roots are probably dead but any larger roots should be conserved. Pot up in moistened soil mix and allow to sit a few days before watering so that broken roots can heal. The website you link recommends digging and storing the tubers out of their pots. This is still common advice for many bulbs and I believe it stems largely from following commercial practices. However, for the hobbyist growing in pots the best way to keep bulbs or tubers in dormancy is to leave them in their original soil and containers. Here they are better protected from the elements (including drying out) and from pests and diseases. Obviously this saves quite a bit of labor as well. In many cases, including tuberous begonias, tubers can be left to grow in the same pot and soil for several years before repotting is needed. With a dry dormancy the soil is only being "used" half the year so it lasts much longer, especially with the incorporation of sand. The goal of the hobbyist is keeping a good thing going rather than production. Dylan * *