Some plants bloom until late fall

What can be planted in landscapes that will give color in late summer and fall?

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The hot, dry summers in our area take a toll on flowering plants. These plants don't produce as many flowers and most quit flowering. There are some plants that will provide color for gardens until frost. Two of these are garden mums and Black-eyed Susan.

Garden mums (Dendranthema morifolium ) give us a burst of color in the fall when used to replace the annuals we have enjoyed since spring. Garden chrysanthemums are valued for their intense color display at the end of the growing season. Flowers are available in many forms, with colors ranging from pure white to yellow, bronze, pink and lavender, coral and salmon, purple, to deep burgundy red.

Mums can provide color until freezing weather arrives if they are watered, fertilized and dead-headed. The right amount of water is vital to success with chrysanthemums. Too little water will slow their growth or stop it completely. Mums especially need plenty of water when they bloom. A gallon of water per foot of plant height once a week is a good rule of thumb.

Mulch will help retain soil moisture. When plants are mulched, the interval between waterings can be longer. Also, mulch helps control weeds and improves the appearance of the landscape.

Mums are heavy feeders. A weekly application of soluble fertilizer is a good practice. Dead-heading is the removal of dead flowers, which will cause the plant to set more flower buds.

Mums grow 11/2 to 3 feet tall depending on the cultivar, growing conditions and whether they are pinched regularly during the growing season. Mums grow best in fertile, highly organic, well-drained soils. They flower best when planted in full sun. Mature plants set in a shady area will give nice color the first year, but do poorly the next year.

Chrysanthemums can be planted in the fall or in early spring. Spring-planted mums will give a more robust, full plant for the fall. Mums should be pinched in order for the plant to produce more blooms. The tip growth on spring-planted mums should be pinched off regularly to cause them to branch. To do this, remove the top half-inch to an inch of new growth about every four weeks from the time the plant is 6 inches tall until early July.

Garden mums are hardy perennials, although many people treat them as short-season, fall-planted annuals. Chrysanthemums grown as perennials will spread rapidly. They should be divided every year or two.

Although mums are hardy, they do have disease and insect problems. They include powdery mildew, Botrytis blight, aster yellows, leaf spots, viruses and foliar nematodes. Reduce problems by limiting the amount of irrigation water that gets on the leaves.

Insects that commonly infest chrysanthemums are aphids, thrips and spider mites. These insects can be controlled with insecticidal soaps or insecticides labeled for these insects.

Another flower that will produce blooms until late fall is black-eyed Susan, Rudbeckia spp . This is a native plant. Most of the Rudbeckia species are annuals, but some are perennials. The perennials will spread by underground rhizomes, while the annuals will re-seed an area.

This plant does best in well-drained soils, and it flowers better when grown in full sun. These plants can be grown from seed that should be planted in the spring. Also, the plants can be divided and transplanted. This can be done anytime of the year, but it is best done in the spring.

Black-eyed Susan starts flowering in mid-summer and will continue flowering if it is dead-headed. Dead-heading not only promotes flowering, but the removal of dead flowers will reduce the chance of disease problems. Unlike many other flowering plants, black-eyed Susan does well under dry conditions.

This plant has many stem and foliar bristles. These hairs tend to catch and hold water. This excess moisture can cause disease problems on the plant. If black-eyed Susans are irrigated, the water should be directed at the base of the plant and kept off the leaves and stems if possible to reduce the chance of disease.

The seeds of black-eyed Susan are used by many birds as food. I have watched goldfinches perch on the plants and pick the seeds from the bloom.

There are other flowers that can add color to the fall landscape, but these two are easy to grow and flower a long time.

Charles Phillips is a retired Columbia County Extension Service agent and operates Hort Consulting. He can be reached at cphillipshort@comcast.net.