Garden Detective: Bringing back a butterfly bush

A swallowtail butterfly takes in the nectar of

A swallowtail butterfly takes in the nectar of a butterfly bush. (July 22, 2007) (Credit: Newsday / Michael E. Ach)

DEAR JESSICA: Our gardener accidentally cut back our butterfly bush in the fall. How should we treat it now -- just leave it alone or prune again? There are a few leaf clusters coming out. --Arleen and John Bergin, via email

DEAR ARLEEN AND JOHN: Cutting down a butterfly bush in fall could be a death sentence for the plant, but if you're seeing new leaves, I'm assuming it wasn't cut all the way back, near ground level, as is protocol for late winter or early spring.

Leave it be. The new growth is encouraging, and it probably will be just fine. In March 2014, cut it to within a foot of ground level. Good luck!

DEAR JESSICA: I'm wondering whether I can grow my own impatiens from seed in organic soil. I realize there is a big problem with these plants, but I thought I could avoid the disease by growing them in my own soil. --Dennis Kenderes, East Meadow

DEAR DENNIS: As you know, impatiens were hit hard last year by a new downy mildew disease, and the disease is expected to continue to target the plants for several years to come. Unfortunately, growing your own impatiens from seed in any soil, organic or otherwise, won't guarantee protection from the pathogen, which is present in the environment. Your best bet would be to substitute another plant in your garden until a cure for the disease is found or breeders produce an immune variety.

In the meantime, stay tuned: I will be offering my suggestions for suitable impatiens alternatives in a column next month.

DEAR JESSICA: I'm hoping you can help me identify and treat whatever is on my cactus. The plant is about 6 feet tall, and I would hate to lose it. --Merry Retus, Orient Point

DEAR MERRY: It looks like you have a cochineal (mealybug) problem. Your first course of action should be to rinse the sticky white substance off with a stream of water that's strong enough to remove it but not so strong that it damages the plant. You can do this outdoors with a hose since the plant is large. If you don't achieve complete success with water alone, apply insecticidal soap (available at local nurseries and big-box stores) with a long-handled brush or a toothbrush (for smaller areas), gently scrubbing off the substance as you go. Allow the soap to remain on the plant to discourage a repeat occurrence.

DEAR JESSICA: I moved to a house in Lake Ronkonkoma in early winter 2011. The house is a short block from the lake, and we have parkland surrounding us on three sides. I love spending time outdoors, but it is no longer a pleasant experience. The problem is that from spring to fall the front and backyards are full of gnats. They swarm all day long, and it gets progressively worse until the weather turns colder in late fall. I have already begun seeing them this spring and need to find a way to eliminate them. Any ideas? --Cathie Karl, Lake Ronkonkoma

DEAR CATHIE: I don't know of any way to eliminate gnats if they're originating in a public lake. But I can offer a couple of suggestions for keeping them from spoiling your enjoyment of your yard. Citronella candles, typically used to repel mosquitoes, have a similar effect on gnats, and Skin So Soft lotion and oil, made by Avon, have been shown to prevent gnat bites when used on bare skin. (Earlier reports that the product repels mosquitoes have been challenged, but studies have shown that because gnats are smaller than mosquitoes, they cannot easily penetrate the barrier the product creates.) There's also anecdotal evidence that another household product, Bounce dryer sheets, repels gnats; the gardeners who swear by them tuck the sheets into their pockets while outdoors.

You also might create a diversion: Heat equal parts jelly and water in a saucepan and stir until it becomes syrupy. Allow to cool and pour to fill a jar, then set the jar in a distant part of the yard. The gnats, along with some other pests, will be drawn to the jar and, hopefully, away from your picnic.