Plant now for cool-season color

Richard Bogren, Gill, Daniel J.

By Dan Gill

LSU AgCenter Horticulturist

(10/26/18) The seasons are changing, and we are entering a transitional period in the flower garden when warm-season bedding plants begin to fade and cool-season bedding plants are planted to provide fall, winter and spring color.

It is possible that many of your warm-season bedding plants are still hanging in there at this point. If that’s the case, leave the beds alone and enjoy the display until next month. But it is important to get cool-season bedding plants into the ground in November or early December at the latest. This will give them a chance to get established before the coldest part of the winter.

Cool-season bedding plants thrive in the cool days and chilly nights we have here during fall, winter and spring. Most will easily tolerate temperatures around 20 degrees or even colder with little or no damage. Some, such as sweet peas, poppies, larkspur, foxgloves, delphiniums and hollyhocks, will wait until spring to bloom. But most will bloom in fall and early winter and then produce a tremendous display in the spring, finally fading out in May as the weather gets hot.

Why plant cool-season bedding plants in the fall rather than in the spring? Well, in addition to the extended period of bloom you get for your investment, fall-planted bedding plants outperform spring-planted bedding plants by several orders of magnitude. This is because fall-planted cool-season bedding plants have the entire winter growing season to develop strong roots and large stocky plants. These large, well-established plants produce more flowers and a more spectacular display than anything you plant in March or April.

Nurseries and garden centers offer a wide selection of cool-season transplants and seeds. Transplants are well-established, blooming-size plants that provide color to your garden right away. Some cool-season bedding plants, such as alyssum, forget-me-not, Johnny-jump-up, calendula, annual phlox and nasturtium, are easy to grow from seed and may be planted directly into the bed where they will grow. A few, including sweet peas, larkspur and the poppies (Shirley, Iceland, California and peony-flowered), resent transplanting and are typically direct-seeded where they will grow.

Before you plant either seeds or transplants, decide where you want to grow them and prepare the soil. Cool-season bedding plants will bloom best in well-drained locations that receive six hours or more of sun daily. Generally, the more sun they receive, the more they will bloom and grow. Pansy, viola, nemesia, diascia and alyssum will bloom fairly well in partly shaded areas where they get at least a few hours of direct sun. Cyclamen, foxglove, nicotiana, forget-me-not, lobelia and primrose are good for the shadier spots.

Do a good job of bed preparation because this makes a tremendous difference in the performance of the plants. Remove any weeds in the bed, and turn the soil to a depth of 8 inches. Spread a 2-inch layer of organic matter (compost, peat moss or rotted manure), evenly sprinkle a general-purpose fertilizer over the bed, and thoroughly mix everything into the soil. Rake the bed smooth, and you’re ready to plant.

When planting seeds, rake the surface of the bed smooth, and carefully follow the directions on the back of the seed packet as to planting depth. Most seeds are fairly small, and planting depth is shallow. Especially fine seed, such as alyssum and poppies, are simply sprinkled onto the prepared soil, pressed down and watered in. They settle into the soil without covering. Larger seeds like nasturtiums and sweet peas are planted about 1/4 to 1/2 inch deep. Plant plenty of seeds, and once the seedlings come up, thin them to the proper spacing indicated on the package.

Because they are quick, easy and give instant results, most gardeners favor using transplants. Plant transplants at the proper spacing into a well-prepared bed, being careful to plant them at the same depth they were growing in the cellpack or pot. Planting too deep often leads to crown or stem rot. It’s a good idea to water in newly planted transplants with a soluble fertilizer to get them off to a good start.

Mulch your beds to prevent weeds, conserve moisture and provide some protection against freezing temperatures. Any mulch would be beneficial. Leaves (especially chopped or shredded), pine straw and pine bark are all suitable and attractive. Although mulch will conserve moisture, additional water will be needed during the first few weeks after planting while the plants get established. After they are established, these plants will generally need little watering during winter. But watering will become increasingly important again as the weather becomes warmer next spring.

Cool-season bedding plants can be used to make your landscape an exciting and colorful place this fall, winter and especially next spring. Careful bed preparation and thoughtful planning when selecting the plants to grow will help make sure you are pleased with the results of your efforts.

You can see more about cool-season color online at

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Planted now, dianthus will provide flowers in your gardens for five or six months from now through spring. Photo by Dan Gill/LSU AgCenter

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With a multitude of flower colors and sizes, pansies are durable and well-justified cool-season bedding plants. LSU AgCenter file photo by Allen Owings

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Sweet peas are among the plants that should be direct-seeded right where they are to grow. Plant them in fall for blooms in spring. Photo by Dan Gill/LSU AgCenter

10/25/2018 7:37:43 PM
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