Get out your pruners. Cutting back flowering plants now will extend summer in your garden
The beautiful blooms of late summer show off this month with dahlias, zinnias, sedum Autumn Joy and rudbeckias performing in the August garden.
To keep your garden in full bloom, be sure to dead head the faded blooms, especially verbena and fuchsias growing in hanging baskets. Harvest dahlias and sweet peas daily for maximizing repeat blooms, and cut back petunias, lobelia and other annuals that grow leggy.
If you harden your heart and ruthlessly cut back plants in a basket or container by one half this week, then fertilize and water, you’ll be rewarded with plants that regrow and perform with more vigor for another two months.
Q. I have something wrong with my dahlia plant that I grew from a tuber. The leaves are mottled yellow, and the plant is slow growing. Do you think this is a disease? I do not see any insects but I baited slugs when the plant was young. — D.G., Bonney Lake
A. My sympathies. It sounds like a classic case of mosaic, a viral disease that is spread by aphids. There is no cure. It is best to remove the plant, tuber and all. Do not compost infected plant material. Make sure you plant clean, viral-free dahlia tubers to keep mosaic disease out of your dahlia bed.
Q. I have enjoyed growing zinnias this summer. I do notice some white powder on the leaves and hope it is not mildew. What should I do? — T., Email
A. Don’t panic. Zinnias can survive the start of a mildew attack if you keep the leaves dry and the roots moist. Once you let a zinnia dry out, the mildew spores can invade the protective layer of the foliage. The secret weapon against mildew is foliage that stays dry.
You can set a protective umbrella over the plants if a rainstorm is expected, and avoid any overhead watering with a sprinkler.
Zinnias love a sunny spot with a rich soil full of compost or manure. Healthy plants are the most likely to resist mildew.
Q. Help me with my begonias. The leaves look a bit shiny and when I touch them, they feel sticky. This does not seem normal. Your advice? — G.J., Tacoma
A. Sticky leaves are most likely honeydew, a sweet little name for insect poop. There are three sucking insects that attack begonias: aphids, mealy bugs and white flies. If you can see aphids on the tips of the new growth, pinch their bodies, or just pinch out the new growth if it is covered with aphids.
If you see white flies fluttering about the plants when you water, then spray with a mild insecticidal soap under the leaves where the white flies set up maternity wards.
Another option is to remove the infected plants and start fresh with plants that offer fresh fall color. Local nurseries will be filling with late summer and autumn color soon. Sometimes when annuals struggle at the end of summer, it is a sign to rip them out and try something new for a late summer renewal.
Marianne Binetti has a degree in horticulture from Washington State University and is the author of several books. Reach her at binettigarden.com.
