Q.Outdoor grown calla lilies
The one tuber I planted about 20 years ago has grown to produce multiple stems that grow to a height of 5 to 8 feet and bloom profusely. We live on the edge of Portland OR and have mildly cold winters. Usually the stems die soon after the first hard freeze and end up to be some partially decomposed leaves in a pile of gray-brown slime that is easily removed at the first signs of new growth. This has been a mild winter and the stems and leaves only died down to about 24 inches tall and are a tangled mess held up by a simple wire frame that gives a little support to the lower canes when the large leaves develop in sprinting.
This happened one other time and I cut the canes to a six inch height. The leaves and canes that summer were all missing the outer tip which produced flowers and leaves with no pointed tip just half of the flower missing. I need to know what to do about spring cleanup of the amazing plant.
You are doing the best thing for them. Continue to keep the dead growth away, and even adding wettable sulfur and dolomitic lime to the soil can help. It sounds like they are getting mild infections from wet weather. This remedy should take care of that for you. You can also divide them out if they get too over crowded.