I planted a "mix" and white Alyssum were the only things that came up AND survived the hungry slugs. They re-seeded heavily, and now the cracks between my sidewalk and raised beds usually put out a dense growth of Alyssum. One year they didn't come back and I had to scatter some more seed.
That's with mild wet winters (Zone 8), and very mild dry summers (but I water my raised beds so they had moist roots).
Since they all grow out of one narrow crack, they do get 12-18: long, but the leggy parts are usually hidden by mounds of blooms all summer. One batch went to seed all at once, I forget whether it put out a second set of blooms. I've never tried shearin g them, I just try not to run over them with the wheelbarrow much.
I got so much high-germination seed the first year I collected it, I haven't bothered since.
(I might already owe some of you seeds, want me to add these to the list to be sent? I've got lots.)
Lobularia maritima from a mix.
Gathered seeds 2009 or 2010 (need to check the packets).
Looks most like: 'Snow Crystals'
white, 6-8" tall, bushy. Sprawls 12-18"
