When you say that "It gets the buds but they don't turn purple" does it actually get flower buds that then turn brown and fall off, or could you be mistaking leaf buds for flower buds? If not, at what stage of development do they stop? It may be that even though to you, the culture is identical, the soil or drainage patterns are different for one to the other, and it isn't getting enough water.

What fertilizer did you use on it this year? If it is a high-nitrogen one, then it may have pushed all leaves, at the expense of flowers. Any future fertilizer should be one with a low first number, since that denotes the amount of N/nitrogen, as compared to P/potassium and K/phosphorous. Roots and flowers are governed by the P and K amounts.

It is possible that the white one is cutting-grown and the other is seed-grown. Seed-grown trees/shrubs frequently take longer to flower than cutting-grown ones. If it was flowering when you got it, then is it getting extra nitrogen in someway, say from run-off from a fertilized lawn?

My 2 purple Vitex, 2 different cultivars, are flowering now, and have been for a week or 10 days, but I don't know how your climate/flowering habits differ from mine - my weather has been screwy this year, more so than normal.

Thank you, The purple one is a bit closer to the drainage swale and my neighbor's leaky lawn irragation so it gets more water than the white one. They are both on the top rim of the swale. The buds of the purple flowers form up but don't swell and develop into the large panicles that the white one gets. They just stay small and green, then fall off. I know its purple because a few of the buds open up very tiny but nothing as showy as the white one. They were both bought as ball and burlap 5foot round shrubs four years ago. The purple one has just never bloomed. I'll keep trying.

Mine's just starting to bud up - not sure if variety or location accounts for the timing; we have a late season because of the maritime climate here.

Too much water could be the culprit, if the buds are rotting. I'd also suspect too much nitrogen fertilizer; I don't think these need any at all, personally.

If it were in my garden, I'd consider digging it up and planting it a bit higher, checking the bottom of the hole for perfect drainage. Or, if it's already clearly as high or higher than the surrounding soil, maybe I'd see if I could add a drainage ditch between it and the neighbor's sprinkler, depending on the spacing.

Mine is only cut back when there's been winter kill; sometimes that means no trimming and sometimes it means cutting it off at the base. It's never been fed anything at all; and it blooms just fine.

I have it for 4 years, it grew fine, nice healthy 5x5' plant...but never bloom. Probably it need more sun than I could provide: 3-4 hours of early morning sun + 3-4 hours from 4pm till sunset. Rest of the day dappled shade.
If this year it will not bloom it will be brought to the spring swap :-(

Vitex like as much sun as you can give them. And they're drought-tolerant once established...translate that to no fertilizer. If you prune it, it will be shrubby--perfectly fine, if you like that. I have a pink one I keep shrub-like and a purple one I am training as a tree. My vote is to neglect your vitex and see if it blooms.

I grow mine in a 16" nursery pot. it is about 5' tall and 4' across. It dries out EVERY day, so I water it twice a day, to prevent yellow leaves. It is just now budding here in KCMO.