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  • July garden tips & tasks

    Make sure the trees and shrubs you planted in spring get plenty of water. The Nashville Tree Foundation advises that trees planted in the last three years should receive 10 gallons per week per inch of tree caliper. Water your trees slowly with a bucket, soaker hose, slow drip hose or watering bag.

    As tomato plants continue to grow and produce, keep the soil around the plants consistently moist. Inconsistent watering is the reason tomatoes develop cracks.

    Summer annuals and perennials such as daisies, glads, zinnias, sunflowers, cosmos and others make beautiful summer bouquets. Cut them early in the day when they’re at their freshest and put them in water in a vase right away. Change the water daily to keep them fresh longer.

    Pick summer squash and zucchini while they are still small and tender for best flavor.

    Watch for tobacco hornworms on tomato plants and Japanese beetles on just about everything else. Pluck the worms off the tomato plants and dispose of them. (If you see one with its back covered with white eggs, leave it; it is being parasitized by a tiny wasp.) Knock Japanese beetles off plants into a bucket of soapy water.

    Cut back the stems of mums once more, before they begin to form flowers. This allows them to delay flowering until fall.

    Lawn growth (and lawn mowing) may slow down as the heat increases. Continue to mow as needed, but don’t cut the grass too short. Provide about an inch of water if it doesn’t rain.

    Don’t forget about those hanging baskets and container gardens in the heat. If it doesn’t rain, you may need to water them daily during the hottest part of summer.

    Overgrown beds of bearded irises should be divided every three to five years. July is a good time for this task.

    You can plant a second crop of summer vegetables that grow quickly. Cucumber, bush beans and zucchini can usually produce a crop by fall if seeds are planted early in July.

    Coleus’ beauty is in the foliage, so when it begins to bloom, pinch off the flower spikes to encourage the plant to grow fuller and bushier.

    Take a daily walk around the garden to enjoy the scenery, but also to spot problems with weeds or bugs before they get out of hand.

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Keep zinnias free of powdery mildew

QUESTION: I love zinnias and plant them every year. Sometimes they do well and look great all summer, but many years the leaves are covered in powdery mildew. How do you get rid of this problem?

Powdery mildew is a fungus that appears as gray or white splotches on leaves, stems and flowers of zinnias and other ornamentals and some vegetable plants. It travels by airborne spores, and thrives when nights are moderately cool and foliage stays damp. A mild covering of powdery mildew is merely unattractive, but a severe case can cause distorted shoots and leaves, misshapen flowers, or can prevent flowering altogether.

The best defense is to grow zinnias in full sun, since hot temperatures inhibit the growth of mildew. Don’t allow them to get too crowded; you want air to circulate freely around the plants. Water only in the morning so foliage has time to dry before nightfall.

I always try to suggest the good-cultural-practices methods first for problem-solving, but there are also fungicides available that can deter powdery mildew. If you choose that route, apply fungicide as soon as you begin to spot the mildew. The University of Tennessee Extension has a short list of products in a publication about powdery mildew here. Be sure to read and follow directions on the product label.

Zinnias are not the only garden favorites plagued by powdery mildew. Lilacs, roses, crepe myrtles and other woody ornamentals, and many herbaceous ornamentals and bedding plants are also targets when weather conditions favor the fungus.

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