This post features some of the biggest and brightest on the Prairie Star list. These large plants offer leaf textures that have been hard to come by for your flower bed, but now you can easily add height, heft and great textural variety to your flower bed designs. Add a few plants with giant leaves to add a little tropical flair, graceful arching grasses or deeply lobed foliage for a lacy texture.
There are two Hibiscus cultivars on the Prairie Star list, 'Maple Sugar' and 'Mahogany Splendor.' These large annuals display a vibrant dark red color through their maple shaped leaves. They can be planted in a cluster and left to grow large to make a great screen or backdrop. Another creative use from the Sedgwick County Master Gardeners was to prune the plants like standard topiaries - what a neat addition to an annual flower bed!
These tropical beauties aren't new to the gardening scene, but the cultivars keep getting better and better. There are many different flower and foliage colors and heights to choose from. We love the new All-American Selections Winner, 'South Pacific Scarlet' which is the first hybrid Canna from seed. It is on the compact side, growing about three feet tall in our trials and displays lush green leaves and red flowers with a touch of yellow.
If you want some extra color in the leaves, Canna 'Tropicana' is a cultivar with very colorful striped foliage. It is taller, reaching a height of almost 6 feet by the end of the season. Fertilizer this plant regularly with a little bit of nitrogen to keep adding more of the brightly-colored new foliage.
Grasses are a great accompaniment to annual flowers. They bring a soft texture to the landscape, plus if it's a large grass planted here in Kansas, you get kinetic motion - the wind is always swirling the blades of grass or the seed heads. Sitting back and watching the plants dance is a meditative way to enjoy all nature has to offer.
Grasses can be perennials, too, like the Eragrostis 'Wind Dancer' and Molinia 'Skyracer' below. The slightest breath of a breeze will set wind dancer in motion. Skyracer has a very interesting plant form with a shorter base and a floral spike that "races" way up to the sky!
Ornamental Millet 'Jade Princess' is an uncommon plant that has chartreuse foliage and enormous furry seedheads. It's a great plant for children's gardens, because everyone who sees it wants to pet it!
Colocasia is a good foliage plant with a unique look. We have grown them in both sun and shade with good results. Below is 'Coffee Cups,' with upward cupped leaves as the name suggests. It is a very interesting plant to watch during a light rain. The leave "cups" fill with water and then tip over to pour the water out, only to refill again and steadily repeat the process. It's almost like a water feature in an oriental garden. Another vigorous one for landscape use is 'Heart of the Jungle.' It readily extends out stolons, 'pups' of new plants creating a loose open clump.
Planning for season long color can be a challenging task. The majority of perennial flowers have a period of bloom lasting only 10 days to two weeks but our growing season may be 30 or more weeks long. To have color all season long requires a study of not only how long the bloom period lasts but also when does it occur.
A simple tool used by flower bed designers is to number the weeks of the year from 1 to 52. Week one being the first week of January. The first week of April is week 14. The first week of July is week 27 and on through the year. The plant chart on our Prairie Bloom list of perennials has a column providing the week of the year each of the plants begin to bloom here in Kansas. The dates are an average over time, so depending on any particular year's weather the actual date will vary. Remember that here on the prairie the average only represents the middle of the extremes and it is the extremes that actually occur.
Use the week of first bloom data to select your plants to have something in bloom throughout the growing season. Annuals are simpler as they bloom for the entire season or maybe we plan for a cool season and a warm season planting. Thirty weeks of color may require us to plant fifteen to twenty different perennials. But perennials offer a much greater depth and breadth of color, form and texture, a richness of palette choices, that annuals cannot match and they don't have to be replanted each year. Just be sure to consider bloom date when choosing which perennials to plant. If you have a big annual 4th of July barbecue for friends and family you may want to consider plants that will be in bloom week 27 to help decorate your yard for the party.
An ideal flower garden should have color spots of annuals for season long color and the uniqueness of perennials for all the visual interest and changing of the season they provide.
When to plant annual flowers is based on soil temperature and not the calendar. Some cultivars tolerate cool soil, while others require warm soil. This spring we have experienced such wide temperature fluctuations that it can be difficult to know what to do.
An easy way to tell soil temperature is simply to stick a thermometer about 4" in the ground. You can take a measurement in the early morning and late afternoon to get a high and low for the day, then average them. K-State also has a good weather data library that shows soil temperatures at weather stations throughout the state.
When the soil temp is around 65 degrees, Petunias, Begonias, Lobularia (Alyssum) and Snapdragons can go in the ground. More sensitive crops like Vinca (Catharanthus), Celosia, Lantana, Melampodium, Zinnias, and Pentas need soil temperatures of 68-70 degrees. These are the flowers that thrive in the heat of the summer and need those high temperatures. Most everything else falls in between.
This is the year to have patience. Wait until soil temperatures are up for a couple of days before rushing out to plant. Our most heat tolerant plants tolerate the heat because they love and thrive in warm soils. Cool damp soils will comprise their root systems and then when the real heat of the summer does finally arrive, they will have few roots to support the plants growth.
We run the annual and perennial flower trials for Kansas State University