Crocosmia is spread like the devil, but can be divided in spring or autumn.
Crocosmias like being crowded.They will become so congested that there will be a reduction in bloom.Lift and divide them every 3 or 4 years for the best performance.If you want to split crocosmias in the spring, you have to do it before the new growth begins.If you like lifting perennial bulbs in the fall, wait for the foliage to die back and turn brown.You probably won't see new divisions this year.You will have a lot of new crocosmias flowering in the spring and summer.
The crocosmia should be clumped up.To cut a circle in the soil around the plant, use a garden spade.
Lift the clump and shake it.If the conditions are wet, rinse it off.
Pull or pry the corms apart.If you prefer, use a sharp knife to split the mass into smaller clumps.
Carefully inspect the crocosmia corms.If you see signs of rot or disease, discard any that is old and withered.It's normal to poke a few of them while you are digging.There are usually plenty of undamaged corms remaining, so throw these out as well.
The plant divisions are about 6 to 8 inches apart.At this time, apply a good bulb fertilization.Follow the instructions carefully.For the most dramatic displays of color, plant groups of 10 or 15 of the same variety.