Now that it is time for cool season annuals, it is difficult to remove warm season annuals if they are still blooming and healthy. that is probably why so many of us prefer mixed plantings, where cool season annuals can be added as needed to replace warm season annuals as they deteriorate. Some warm season annuals that are actually perennials, like wax begonia and busy Lizzie (impatiens), can be cut back and overplanted with cool season annuals, so that some might regenerate next spring as the cool season annuals finish. Petunias may be looking overgrown and tired, but are at least easier to remove without guilt.
Pansies and smaller but closely related violas are probably the two most popular of cool season annuals. They work something like petunias, but for autumn and winter. They are commonly grown in uniform beds, but work just as well in mixed plantings. There are not many colors that can not be found in pansies, although only a few of the more popular varieties can be found at any particular nursery. Some are ‘solid’ colors. The most familiar varieties have those funny ‘faces’ that pansies are known for.
The various primroses require a bit more effort because deteriorating flowers need to be removed. They can also be a problem for the few who are allergic to them (like poison oak). Like the warm season annuals that can survive as perennials through winter, some primroses, particularly English primrose, can survive through summer as perennials. English primrose displays bright cartoon shades of almost any color. Fairy primrose are more commonly pastel shades.
Stock has an intense and distinctively rich fragrance. Taller types are excellent cut flowers, but are not so practical for uniform beds. Even shorter types are probably best in mixed plantings, or in borders with lower flowers in front. The single or double flowers can be white, pink, purple and almost red.
Ornamental cabbage and kale are grown for bold rosettes of colorful pink, white or pink and white foliage. The shades of pink range from soft light pink to rich purplish pink and almost red bright pink. Cabbage provides more color. Kale has more variety of foliar texture. Ironically, both look rather weedy, and should be removed as they begin to bloom in spring.
Chrysanthemum are strikingly colorful cool season flowers, but rarely bloom as uniformly as they do when first planted. Because they bloom so profusely, they need to be groomed frequently. If they get what they want, they can perform for several years, blooming all sorts of shades of yellow, orange, red, pink, purple and white. Chrysanthemum also displays a broad range of flower structures and sizes, from minute to jumbo.
Sweet William, Iceland poppy, calendula and alyssum are also in season. Yellow or orange calendula, with single or double flowers, is best through autumn, but may mildew by winter. Alyssum is white or subdued shades of pink or purple, and is actually good throughout the year, and can self sow indefinitely.