hi when you split and divide a hosta it is best done in the spring just as soon as you see the new growth appearing.so i would say in the spring.good luck.

Hi Macie I would agree with Kennyboy, but if you cant wait until spring and you are not too bothered about splitting your hosta up, it will not be a problem in autumn. Wait until we have a bit more rain and the ground is well watered and you should have no bother. It is easier to divide in spring when the "horns" appear dont wait for the foliage as you are more likely to damage it when splitting apart. - Good luck and happy gardening.