For the last few years I've been able to purchase what the garden center calls "aggressive alyssum". I have no idea what it's Latin name is. It spreads to about 18 " and is an annual. What should I do to maintain blossoming when it appears spent and dying out?
Alyssum likes moist soil so put it in a place with other moisture-loving plants. A gentle shearing, fertilizer and water may get your plants flowering again. Almost all plants that bloom all summer use up their springtime fertilizer by now and need another, more modest dose. The heat of summer is brutal on many plants and flowering may cease but more vigorous flowering resumes with cooler weather.