By Jeff Oster, UC Master Gardener of Butte County, October 5, 2018

The Asteraceae is a very large and widespread family of plants which includes many very common species of garden flowers, such as asters, daisies, zinnias, chrysanthemums and sunflowers. This plant family is also called Compositae because its members generally have composite flower heads made up of a central disk of tiny flower without petals, surrounded by ray flowers that do have petals (so each “flower” head is actually composed of multiple flowers).

Composites are mostly herbaceous, but the family also includes shrubs, vines and trees. They have worldwide distribution, but are most common in arid and semiarid regions of subtropical and lower temperate latitudes. Most like full sun and good drainage, but will tolerate a variety of soils.

Economically important composites include safflower (for oil); many edible crops such as artichoke, lettuce, cardoon, and chicory; herbs like stevia, tarragon, coneflower and chamomile; and the humble dandelion, reviled in many quarters, but considered a useful edible in others. This article series will concentrate on ornamental long-flowering perennials adapted to our climate.

Ornamental species of Asteraceae have a range of heights, plant habits, and colors to choose from. Different species of composites can be effectively integrated into the home garden, because their similarity of flower form provides harmony in a display. Try layering plants of different heights and habits, with the shortest in front, planting them in masses. Another approach is to plant in groups of three in alternating groups, or in rows of different species. Select complementary colors (for example, pairing yellow with violet, or orange with blue), or work with a palette of primary colors (blue, red, and yellow). Large plantings of different species in a single color range can be very dramatic: try cool and orange yellows together, or yellow orange with red orange, or blue violet with red violet. Plants in the following three genera are some of the most reliable composites for our area.

Coreopsis

Coreopsis is an old reliable garden favorite, with blooms in shades of yellow, orange, maroon, and red. Some varieties bloom all the way from mid-spring through fall, and make good cut flowers. Coreopsis love sun and are not finicky about soil – they will do fine in average to poor soils, but well-drained garden soils are best. They are drought-tolerant and low-maintenance. Deadhead flowers for longest bloom and divide every few years when overcrowded to re-invigorate them. They are easily propagated by division, stem cuttings, and seed. Coreopsis are deer resistant and attract birds.

C. verticillata tolerates drought and neglect, and blooms from summer through fall. C. verticillata ‘Moonbeam' has pale yellow flowers, while the flowers of ‘Zagreb' are more golden yellow. The bright yellow C. auriculata ‘Nana' is a low-growing form that spreads by underground runners to create a two-foot-wide clump in a year. Useful in front of taller plants, it too has a long blooming season if deadheaded faithfully. Another bright yellow form is C. grandiflora, a tough variety that reaches two feet in height and spreads to three feet wide and blooms throughout the summer.

Gaillardia (blanket flower)

Gaillardia is a low-growing summer bloomer with daisylike flowers in shades of red, yellow, and orange. Plants are mounding to slightly sprawling. Gaillardia requires full sun, and tolerates drought and poor soil, but needs good drainage. Unfortunately these plants tend to be short-lived. Deadheading is not necessary but helps prolong plant life. Cutting plants to 6 inches in late summer may increase their chances of surviving through the winter. They can be propagated from seed, basal cuttings, or division. Dividing them in spring or early fall every two to three years will improve their vigor.

Butterflies and native bees love to visit these flowers, and their seeds provide food for birds. Pest problems are few; deer and rabbits avoid Gaillardia. The taller cultivars of Gaillardia make nice cut flowers.

Some varieties of Gaillardia to consider: Gaillardia aristata is a robust, large-flowered perennial which flowers in shades from yellow to red; it is native to the prairies of North America, and is often included in wildflower mixes. Gaillardia x grandiflora grows tall -- up to three or even four feet and tends to flop. G. x grandiflora ‘Tokajer' is tall, perhaps reaching three feet, with pure orange flowers. Gaillardia come in a wide variety of flower color, including various shades of red and yellow, and some have orange or maroon bands on the petals.

Other useful more compact cultivars in our area include G. x grandiflora “Arizona Sun” which has stunning mahogany-red rays rimmed in golden yellow. It reaches a height of twelve inches, and blooms sooner than many other cultivars. G. x grandiflora “Mesa Peach” and “Mesa Red” grow a bit taller, to eighteen inches, with peachy-yellow and deep red petals, respectively

Aster

Finally, plants in the genus Aster are perfect plants to think about at the beginning of the fall season because they add spectacular color in the autumn. Aster plants are very durable and long lived. Plant asters in early to mid-spring (or buy them now, in pots, to add fall color to a sunny porch or deck). They should be trimmed back in early spring and again in June to maintain bushiness; deadhead occasionally for more blooms. Divide every two to four years in the spring to maintain vigor and flower quality. The plants can be used in many places: asters work well in borders, rock gardens, or wildflower gardens. As a bonus, asters attract butterflies.

Many varieties of Aster are available, Aster × frikartii 'Wonder of Staffa' has the longest blooming season. It is a repeat-blooming aster that produces lavender-blue two-inch-wide flowers from summer into fall on bushy plants. It grows to three feet tall and one to two feet wide and prefers full sun and average, well-drained, dry to medium soil. Cut plants back by half in midspring to encourage bushiness. Divide in spring to maintain vigor as required. But be advised, this is a plant for USDA zones 4-8, a bit cooler than the valley floor, so it will not live as happily here as it will in the foothills.