Before you can hope for any seed.....of any plant, shrub, tree, or whatever, it must bloom.
From flowers, you then get seed and the time you harvest them is according to the particular plant. You have to keep an eye out for when the plant flowers and when it goes to seed.
You've seen the dandelions on the lawn....bright yellow flowers...gather them and make dandelion wine....but wait too long and the white clouds of seed are everywhere.
Each flower has a time to live and a time to die....but before it dies it tries to advance its young...by going to seed.
When shrubs have a difficult time to flower, there is a couple ways to encourage it to produce bloom. One is to put it into stress by cutting the outward reaches of its roots...beyond the branch tips. WE encircle the plant cutting the roots there.
Another method employs the use of the element 'phosphurus' which, when the roots take it in, encourages development of roots and bloom. Miracle Gro fertilizer 15/30/15 has its increased contents of phosphurus to perform this task, and why, its a fertilizer especially designed to increase flower production.
And from flowers, we get seed.
As far as cross polination, its not as tricky as you might think. Try doing some research in 'apple orchards' and how to polinate fruit trees. As far as helping plants polinate, do your best to encourage insects that do that around your home. Bees are not the only insect that does this. Butterflies, ants, ladybugs and most any other insect that crawls into a flower, picks up the pollen and visits other plants all in a day's journey.
Plant shrubs and flowers that encourage these visitors to your garden. You are then helping the environment and seeing to us having fruit and vegetables on our dinner table.