The movie "You've Got Mail" was just on HBO; it reminded me that it was time to address some reader queries.
Q: I have two small Alberta spruce trees in large pots on my patio. This summer one of them suddenly turned brown. I suspect it was mites. What can I do to prevent this from happening to a replacement plant, or are these just a bad bet in this area?--Gregory Phillips
A: They are alpine plants and, as you said, a bad bet in this area because of spider mites. I don't think that spraying is the answer. But with just the right growth situation--lots of air circulation and a very light aerated, gravelly mountain-like soil--they should thrive. If they lose ornamental value, I recommend that you remove and replace with evergreens that are more insect and disease resistant, such as falsecypresses (Chamaecyparis species), hollies, yews or other dwarf conifers other than Alberta spruce.
Q: We are about to buy several leyland cypress trees to plant as a border near the edge of the front and side yard. Is now a good time, and what are their needs?--Jill and Bill Konrad
A: I recommend planting leyland cypresses in early spring because they are shallow-rooted evergreens. The freezing temperatures at night are another reason it would be good to wait. Plant them at least three to four feet to your side of the property line and about four to five feet apart. They like moist well-drained soil with at least 10 percent compost mixed in. Keep them moist. Once established, they're more drought-resistant.
Leylands must be planted in full sun. Shear annually if necessary to control growth and to maintain them as screening plants. They can be kept at any height.
Always trim, keeping the bottom wider than the top, or they'll shade their own lower limbs and lose them.
Q: We have a plentiful supply of pine needles that we would like to use as mulch for our acid-loving plants. We were nearly done piling needles around the plants when we suddenly wondered if pine needles might be harmful.--Jabez McClelland and Cathy Chow
A: Pine needles would be a good mulch for pines or any other acid-loving plants, such as azaleas, rhododendrons, mountain-laurels, hollies, dogwoods, willow oaks and others that like the soil in a pH range of 5 to 6. They'll control weeds while adding nutrients when spread over the roots of these plants. They are not good to use on plants that like more alkaline conditions, such as lawns, vegetables, and many perennials and annuals. If pine needles are added to compost, keep them in amounts of no more than 10 percent of the pile, so the material doesn't get too acidic.
Q: Our screening is white pines in rows up to 15 feet tall. This year most of the pines have had their leaves turn yellow and fall. There is a carpet of needles around each affected tree. The soil just beyond the original root ball is fairly dense red Virginia clay. Is this shedding normal?--Monica and Ray Reilly
A: White pines shed in fall. It's normal. The excessive needle drop that you have seen on many white pines this year might be due to the recent drought. New growth in spring should be fine, provided they are in sun and 10 to 15 feet apart. To help condition that rich Virginia clay, lay two inches of composted leaves over the roots.
Q: Four elegant old hemlocks have had an infestation of woolly adelgid the past two years. I spray four times from March to October, as far as my hose end sprayer will reach, about 30 feet, using Cygon or Orthene and a dormant oil. There are another 30 feet of branches I haven't figured out how to spray. Is it the right thing to be using or is there something better?--W. Leginski
A: You are using the correct materials for adelgid control and will probably eradicate them where you are reaching them. Horticultural oil and Cygon (as long as it is labeled for hemlock adelgid) are the most successful insecticides, but only where they contact the plant. They don't work in winter when the adelgid is dormant. A tree company will have the equipment to spray entire trees.
Apply horticultural oil in spring, summer or fall when the adelgids are crawling, generally between May 1 and Sept. 30. There are two theories: apply the insecticide at the beginning and end of May or apply it once in May and once in September.
If the infestation seems to be lessening, you could cut the spray to September only and kill fewer beneficial insects. If infestation recurs, twice-a-year sprays will become necessary. Always follow label instructions.
Q: My cousin in Arlington sent me a clipping of your Oct. 16 article about small shrubs. I live on Block Island, R.I., which is about 12 miles into the Atlantic Ocean. Will the following species of shrubs do all right in our environment: itea, nandina and Otto Luyken cherrylaurels?--Chris Warfel
A: Your hardiness zone should be similar to eastern Long Island, which is the same as Washington. Itea is fully hardy and will develop gorgeous red fall foliage. Nandina and cherrylaurel also should be fine. But because you are in the middle of the Atlantic Ocean instead of being along the Potomac River, your plants might need to be protected from desiccation by prevailing winter winds and could have a limited tolerance to salt air.
Site them to protect from winter winds. Try one or two and see how they perform. If they succeed, plant more. Confirm their hardiness with local garden center staff or your county cooperative extension service.
Lerner is president of Environmental Design in Capitol View Park, Md. His e-mail address is firstname.lastname@example.org