Cool weather can be hard to garden in, because you never know how long it will last. But there are many garden flowers that prefer the cool days of spring and fall. Often gardeners think only of perennials for a sequence of bloom. Many cool season annuals look wonderful in containers and growing these flowers will make your gardening season seem that much longer. If you live in a warm climate, some of these flowers will bloom from fall through spring.
1. Bachelor's Buttons, Cornflower (Centaurea cyanus)
You won't often find Bachelor's Buttons at the nursery, but they grow very easily from seed and will reseed freely. A cottage garden plant, Bachelor's Buttons give its best display in cool seasons, so if you started some in the spring, watch as they perk up again this fall.
Diascia though relatively new in gardens, became popular quickly. The tiny, profuse trailing blossoms make it perfect for containers. Diascia is generally grown from cuttings, which can make it an expensive annual. But you may be able to over winter yours indoors or take your own cuttings. Diascia are perennial, with a good winter, in USDA Zone 8 or higher.
Where summers are too extreme to grow delphiniums, larkspur makes an eminently acceptable substitute. If you start your larkspur off in the spring and keep it deadheaded throughout the summer, a little extra food should revive it for the fall show.
Lobelia will give out on you during the summer. But given cool temperatures, it will bloom with profusion If you planted yours in the spring, once the flowers start to slow down, cut it back a half and allow it to regrow and rebloom.
Nasturtiums will bloom throughout summer, well into fall. They are rejuvenated by the cooler air. Even their crisp fall colors advertise that they belong in the fall garden. Nasturtiums don't transplant well and you may be better off direct seeding. Keep them well watered in the heat of summer.
Nierembergia 'Mont Blanc' rescued nierembergia from obsolescence Nierembergia is hardy to USDA Zone 7 and can even be over wintered indoors, but you might not bother because it is fairly easy to grow from seed. 'Mont Blanc' won the All America Selection award, but the blue flowered varieties are getting the attention now.
Gardeners think of petunias as a bedding mainstay. Petunias actually do their best blooming in cool temperatures and there are so many to choose from. The Wave series has become especially popular and if you, like me, don't like deadheading, Wave petunias are for you. The tiny calibrachoa petunia make a nice textural accent in containers.
Snapdragons offer you color and a bit of height, depending on the variety. There are also new trailing snapdragons that work wonderfully in containers. Look for the Luminaire series. Snapdragons are hardy at least to USDA Zone 8. With some protection, they may also survive in Zone 7.
10. Viola and Pansy
You may still have some pansies from last spring, languishing in your garden beds. Look around and see if they are perking up for fall. Violas and pansies will bloom for weeks. Deadheading will keep them setting new buds. Look for some of the newer varieties that can handle a slight freeze.