I was told if you removed the last bloom, the tiger lily will never bloom again. Is that true? I believe the tiger lily will go ahead and germinate and bloom the following year.
You're basically right. Here's some information you might find useful: https://www.gardeningknowhow.com/ornamental/bulbs/lily/tiger-lily-care.htm
http://www.ndsu.edu/pubweb/chiwonlee/plsc211/student%20papers/articles02/dtheurer/dtheurer.html
I have just taken my tiger lilies from plastic pots and want to know whether to dry them out now (Sept) and replant them in the spring or whether I need to plant them straight away.
Tiger lilies are winter hardy in your area, if I'm understanding the climate correctly. You should go ahead and plant them now - you can put extra mulch over the bed to help protect them through the winter. This article has more information you might use: https://www.gardeningknowhow.com/ornamental/bulbs/lily/tiger-lily-care.htm
I planted about 2 dozen Tiger Lily bulbs last year but they never bloomed. I wonder if I should remove them from the pots they are in now, dry them off, put them in a dark place until later in the fall and then repot them? What do you suggest? Thanks very much.
Here is a link to proper planting and care of Tiger Lily bulbs.
https://www.gardeningknowhow.com/ornamental/bulbs/lily/how-to-grow-lilies.htm
I have got some tiger lily seeds from a friend's plant. Do you let them dry before planting them next year or can I plant them now? Thank you.
You can go ahead and plant them. Since it takes a while for these plants to grow from seeds, rather than bulbs or transplants, you will need to be patient. Do not expect flowers for at least the first year or two.
I have several plants but they are too large for the planter and I would like to move them to a roomier planter.
It would be best to wait until they are done blooming to move them to a new pot.
https://www.gardeningknowhow.com/ornamental/bulbs/lily/tiger-lily-care.htm
How to prune, and what is considered the stem? It would help if I can see a photo.
Tiger Lilies require such little care, the only reason you might want to prune them would be to deadhead the spent blooms at the end of summer, but you actually don't need to if you don't want to -- they'll fall off in the fall and the main stems will dry up (you'll want to pull those out or cut them down either in the fall or next spring). There will be a main stem from which several lilies shoot out, each on their own "child" stems. You can "prune" your tiger lilies one of two ways: cut each individual dead flower off by cutting that flower's own stem, or wait till all the flowers on the main stalk are dead and cut the parent (main) stem almost all the way down.
This article provides some more information about growing Tiger Lilies: https://www.gardeningknowhow.com/ornamental/bulbs/lily/tiger-lily-care.htm
When/how to plant tiger lily bulbs?
Spring is the best time to plant most bulbs, but Tiger lily flowers are so hardy that I've planted in early summer while the weather was still cooler, with great success. I've even separated and transplanted lilies in the middle of summer and although the transplanted bulbils didn't bloom that year, the leaves stayed green and I got flowers the following year.
It's important to give the transplants plenty of water but don't keep the soil wet.
Keep in mind that it may take up to five years before the newly-planted bulbils flower. This article may help you: https://www.gardeningknowhow.com/ornamental/bulbs/lily/tiger-lily-care.htm