One of my early memories of visiting my grandmother was filling my pockets with the large black seeds of the old-fashioned four o’clocks (Mirabilis jalapa) by her kitchen door. They were the perfect food for dolls or could function alternatively as small missiles if a battle ensued with my younger brothers. I do not remember being interested in the fact that these colorful, tubular-shaped flowers opened, as if on cue, at about the same time every afternoon. That fact fascinates me now. When I mention to fellow gardeners the association of four o’clocks with my grandmother, I receive many nods of agreement. It would seem that four o’clocks were the quintessential grandmother’s plant of the 1950s.
For centuries, gardeners have grown brightly hued annuals from seed, since seed is reliable, easy to transport, and relatively inexpensive. These plants provide season-long color (and often an intoxicating fragrance), which can be used in masses or as fillers in an herbaceous flower border as well as in containers. Some so-called annuals—for instance, four o’clocks or heliotrope (Heliotropium arborescens)—are actually tender perennials that function as annuals in colder zones. Each of the following annuals has pleased gardeners, both in the United States and abroad, for hundreds of years. In many instances, heirloom cultivars are still available to strengthen our roots and solidify our connection with those gardeners who have gone before us.