When we moved to southern California, I purchased and planted 100 watsonia corms (I also transplanted several of my mature corms from my northern California home, in center of same bed). All produced 2 ft green sword-like leaves (new corms seem to be a bit slimmer than transplanted ones). It took about 3 yrs for the transplants to bloom but none of the now 5 yr old new corms have ever produced the bloom stalk or a bloom, only sword leaves. Do they just need more years to mature or is something wrong? Love these flowers and any help will be appreciated. Carol
Though Watsonia does need fertilizer, be careful to not overfeed, as this will cause leaf growth and no flowers. I suspect that may be the isssue.
Here is a link about Watsonia care. Hope this helps to get those blooming for you!
https://www.gardeningknowhow.com/ornamental/bulbs/watsonia/growing-watsonia-corms.htm