Garden Detective: No impatiens in pots

Ball horticultural mixmasters Laguna beach Calibrachoa and burpee Ball horticultural mixmasters Laguna beach Calibrachoa and burpee flash mob bluerific petunia growing in pots in Jessica Damiano's garden. (May 2013) Photo Credit: Jessica Damiano

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Jessica Damiano Jessica Damiano, Newsday columnist

Jessica Damiano is a master gardener and journalist with more than 20 years experience in radio, television, print ...

DEAR JESSICA: We live in Cutchogue, where the deer eat everything in sight. So to enjoy the flowers, we hang pots of impatiens around the porch. After reading your advice against planting impatiens this year due to widespread disease, we're wondering whether impatiens in hanging pots are at risk, too. --Ruth Beyer Hoffman, Cutchogue

DEAR RUTH: Unfortunately, impatiens in pots will be just as susceptible to downy mildew disease as those in the ground. The pathogen, which was prevalent in the Northeast last year and is expected to continue to be a problem for years to come, is airborne. It would be best to stick to one of the alternates I wrote about in my last column. This year, my pots are filled with calibrachoa and petunias.

DEAR JESSICA: We have a mature, 20-year-old leggy lilac that's 15 feet tall. Can I cut it down to 8 feet and still get future blooms, or should I replace it? --Jim McCann, Douglaston

DEAR JIM: You can rejuvenate your lilac by cutting it down to about a foot from the ground. This should be done in late February or March, while the plant is dormant, so best to hold off another year. This will force the plant to produce a lot of shoots during the following summer. Then, in late winter, remove most of the weaker stems that grew, cutting them at ground level, leaving several strong, healthy ones to grow into the new plant. Prune those strong, healthy stems just above a bud to stimulate branching. It should fill out nicely in a couple of years.

DEAR JESSICA: My white hydrangeas are turning red and blue. How could this happen? --Toby Cohen, via email

DEAR TOBY: Many varieties of hydrangea are affected by the pH of the soil in which they're planted, so even if they were white (likely slightly tinged either blue or pink) at the nursery, once planted in your garden, they could very well turn pink or blue. Acidic soil causes the flowers to bloom blue, while alkaline soil induces pink blooms. A soil pH of 7 is considered neutral. A reading of less than 7 indicates acidic soil; numbers higher than 7 are alkaline.

It's possible to change the color of hydrangeas either pink or blue by manipulating the soil's pH. It's important to note it's a lot harder to turn alkaline soil acidic than the other way around.

To make acidic soil more alkaline and turn blossoms pink, simply incorporate lime into the soil. This works pretty quickly and may not have to be repeated for a few years. But to make the soil more acidic, you have to add sulfur, and repeat applications will be needed to maintain the pH. If you choose to use sulfur, be sure to follow package instructions very closely and carefully.

Garden Club of the week

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SWEETWATER AFRICAN VIOLET SOCIETY :The society’s mission is to educate members and the public about the care, propagation and hybridization of African violets. Members can attend the annual African Violet Society of America conventions.

Meets: 7:30 p.m. first Wednesday of each month from September through November and January through May

Location: West Sayville Fire Department, Montauk Highway and Atlantic Avenue

Dues: $10 annually, includes issues of African Violet Magazine every other month.

Contact: 631-589-2724; jeancat489@aol.com, or club’s website, avsa.org

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