Some folks want to start their own calla lily seeds because they see them produced on the stalks. In a good warm year, calla lily seeds are found hanging on the plant just behind where the flower was. (yes, they do set seed and yes, you can grow new plants from these seeds) :-)
When the seed pod is ripe, it will turn yellowish and go soft. It is best to allow the pod to ripen on the plant as it will mature there.
The seeds inside will be black and shiny when ripe
A black calla lily seed ready for sowing
Remove the pod from the plant when it goes soft. Break it open. Remove the seed from the pulp (an old colander, running water and some gentle finger work will do this best).
Dry the seeds for a bit until the excess water is gone and they can either be stored dry and cool or planted right away (planting right away is best).
Sow by barely covering the seed with soil (no more than 1/8 inch deep) and put 2 to 3 seeds in a small pot.
The soil must be kept warm at 70F or you wont see germination.
(Remember soil temperature is usually 10F below room air temperature). Water when necessary with warm water.
Use grow lights if you are sowing them indoors.
You should see seedlings within two-three weeks or sooner.
Two week old seedling - see the good root structure. You can transplant to another pot at this size if you're careful.
Grow these seedlings in their pot until it is time to plant outdoors in the garden. (frostfree)
Plant outdoors at the same depth as they were in the pot. Do this as carefully as possible to avoid disturbing the roots.
Grow them as you would any other small garden plant. Weed regularly and do not let them any water stress. They will not likely flower the first year from seed but if grown on fertile soil should bloom in year two.
And that is how you harvest and grow calla lily seeds.
Seedlings in their pot, the largest leaved ones are "almost" ready for transplanting while the smaller ones need to be left alone for another few weeks.