FULL sun means different for different climates, plants. For tomatoes 6 hours is considered full sun. But then it is not just DIRECT sun. indirect and defused lights also have benefits.
In fact alliums, can tolerate shade better, as they are generally COOL crops.

So, the question is, when your tree grows leaves, will the bed see ZERO hour of direct sun ?

Thanks for responding!

The place I'd like to put them will only get maybe 1 hour of direct sun in the morning once the tree's leaves fill out completely.

Maybe I should have them somewhere else. I do also have some blue allium bulbs to plant which I've read can tolerate less sun? Maybe it would be ok there?

I would look at early spring-blooming bulbs like crocus and scilla instead, or even miniature daffodils.

I hope it's okay to add to this thread. I have several spots in my front yard that aren't under trees. However we have Eastern exposure, so there's pretty much alternating sun and shade throughout the day.

Has anyone had success with ornamental Allium plants in such an environment? I want to plant some in the worst way, but I don't know whether it would pay off or not. Thanks.

Ms Xeno- I planted several varieties in pretty shady spots last fall (since it was all I had available and I thought I'd take the chance). I'll post back when they come up and let you know how they do! For what It's worth, I've read that the azure alliums do better in shade than others.

I have several different types of allium growing under an Pin Oak tree. Which gets sun until the leaves come in then its filter sun only. Allium will grow almost anywhere.

Thanks, arylkin (I hope you get the nice blooms you want) and mori1. I appreciate it. This Fall, if finances permit, I'm definitely going to reserve some space and try some out.