Thanks for writing. Do you know what type of magnolia they are? If so, check their hardiness ratings --- it might be that you have types that need a little more winter cold than your area gets.
Do you prune your magnolias at all? Pruning too hard or at the wrong time of year may prevent them from blooming.
Are they putting on lots of leafy growth? Too much fertilizer, especially if it has a lot of nitrogen in it, can encourage magnolias to put on leafy, vegetative growth at the expense of flowers.
I hope this helps.
---Justin, Senior Garden Editor, BHG.com"