Garden Detective: Caring for a butterfly bush, Japanese red maple tree
DEAR JESSICA: I have Japanese red maple trees on my property. Some are an awful shade of green, some are red, and one has a red side and a green side. They all came from the same parent tree. I would like them to be rich burgundy. Would the soil be at fault? --Anthony Angieri, Medford
DEAR ANTHONY: Japanese red maples (Acer palmitum) thrive best when planted in acidic soil, but it's likely that sun exposure is responsible for the color variances you're noticing. I'm guessing the red trees are in the sun, the green ones are in a shadier area, and the bicolor tree might be situated in a spot where the red side is facing west or the green side is shaded by larger trees or facing a structure, like a house or garage.
It's also common for the leaves of some varieties to turn green during summer and back to red in fall, so maybe a transition was in progress when you wrote. And trees grown from seed are more likely to lose their red color in summer. You say all your trees have the same parent, so if you propagated by seed or pulled up and replanted seedlings, you found growing in the garden, this could be an explanation as well.
DEAR JESSICA: I bought four varieties of butterfly bushes and planted them in pots. They seem to be doing very well, but now that it is getting cold, should I cut them flush in their pots or bring them in? --Joe Tricarico, Massapequa Park
DEAR JOE: Add an inch or two of mulch over the soil to protect roots from winter temperatures. They should be cut down to about 6-12 inches tall in March. If it appears they have outgrown their pots, that also would be the time to replant them, taking care not to disturb the roots too much.
DEAR JESSICA: In June 2010, we planted two Miss Kim lilac bushes. They have grown nicely and produced beautiful flowers. By midsummer of each year, the leaves on the top half of each bush dry up, turn brown and fall off. I've been told at a local garden center that they are not getting enough water and to flood them with an open hose. We had a sprinkler system installed this past spring, but the same thing happened. I've checked for insects but found nothing, above or below ground. Can you tell me what could be causing the defoliation of the plants? --Phyllis Vogel, North Merrick
DEAR PHYLLIS: Once established, lilacs generally get by with very little care. All they really need is plenty of sunlight, soil with a neutral-to-alkaline pH, sufficient space and air circulation. Even supplemental water isn't usually needed after they've settled in.
Still, it is possible your plants aren't getting enough water, as that's the most common cause of leaves drying up. If that's the case, the advice you were given was correct: Water deeply twice a week with a hose directed at the roots for 30 minutes or more, depending on the force of the water stream.
Sprinkler systems aren't ideal for watering any plants because they don't direct water to the roots, they sprinkle foliage -- which can result in the mold and mildew diseases to which lilacs are especially susceptible -- and would have to be left on for hours to achieve the type of soaking that's required.
I wonder if your plants are located under eaves or if your soil is sandy and draining too quickly. Incorporating compost into the soil and applying mulch will improve moisture retention. If a structure is blocking rainwater from reaching roots, relocate the plant.
There are some diseases that could result in brown leaves, but if affected, the whole plant, not just the foliage, would be in decline.
GARDEN CLUB OF THE WEEK
Long Island Rose Society
Meets: 7 p.m. on the second Friday of each month, March through December
Dues: $25 per household
Contact: 516-872-2332, longislandroses.org
Affiliated with the American Rose Society, this club sends members monthly newsletters that include growing tips and information about upcoming meetings, garden tours, garden parties and rose shows. An annual rose show is held every June at Planting Fields Arboretum in Oyster Bay.