Sounds like too much nitrogen in the soil. Trade ya, though mine is about 2 inches high and not blooming.

Here's a shot of mine battling it out with my strawberries. ;)

I've never seen alyssum that was so tall as you're describing!

I've the same growth problem with alyssum the last two years. Using Steve Solomon's organic fertilizer (cottonseed meal, bone meal, kelp meal, lime) the plants were/are over sixteen inches tall and 24 inches wide. The two varieties were both supposed to be 4 to 6 inches tall. Snow Cloth Alyssum this year. Two varieties of alyssum, Aphrodite Red and Wonderland Copper are closer to size, 8 inches instead of 6 inches.

I've sheared the white twice to keep it small.

Very strange behavior for a "small groundcover" annual.

Laurell, I'll trade you! Yours look much better behaved than mine. I grew them from seed and have them planted in a couple of places and they are all growing rampantly. I don't think it is too much nitrogen because other plants in the same area are not doing too much growing. I guess it must be the variety...