JB made a good point, if it’s a seedling tree, yes it could take a lot longer to start bearing fruit. Starving your tree of nitrogen before new flushing is one way, but they still need micro,s and p, k., just don’t cut the tree down.

Since you mention several months time frame, it's possible that they were actually affected by the big cold front that came in early March in your area. 4 of them already look like the color of fading blooms. However, you can keep them on as long as the bloom stalk is still healthy looking and it could be that in your local area, they will still be coming up (though I have seen many people's daffodils already in bloom, but I can't say if yours are late since there are daffodils with different bloom times)

Cynthia, thank you for the photo! Gorgeous!!! Meg, don't water too sparingly ... LOL. The roots need moisture to grow. My theory is after the roots have been twirling around the pot for a bit the plant 'decides' that this is as far as they're going to get and begins the blooming process to replicate itself. That may be why a more mature plant will bloom after the flood and drying period as mentioned above. It 'thinks'; "Well, I may die soon so I better use all my energy to bloom and produce seeds." However, the varieties we grow are sterile hybrids and don't make seeds. The article below says not to use saucers under pots. Perhaps saucers might promote rot in 80 to 90 degree climates like some parts of California and Florida, but with our 105 to 110 + degrees in summer they need all the help they can get so I use saucers. The saucers retain a little water and gives the soil time to soak it up. The peat moss in many potting soils become resistant to absorbing water after drying. I even mix extra water retaining crystals in my potting soil. Miracle Gro contains it already, but not enough IMHO. Sometimes if the soil has really dried out I either set the pot in a tub of water to hydrate, or lay a very slow dripping hose in the pot. Plus there are differences in varieties. I notice some begin blooming later/earlier/longer than others, but all the hybrid varieties available in nurseries bloom well. Do keep us posted. Wishing for you the best blooming bougie in the world! ... :-) Here is a link that might be useful: How to water bougies ... mostly about bougies in ground.

Are they in rich soil, or do you fertilize them? Milkweeds do well in lean soils.