A Tree Grows in Cambridge

What fast-growing trees are suitable for a small backyard in Cambridge? An old tree was cut down, so I assume the soil is OK. The spot gets some sun and some shade. Please eliminate any trees that are disease-prone or not insect-proof.
LOUIS SOTIS /// Waltham

An often-used street tree, Pyrus calleryana, or callery pear, is one suggestion. `Bradford' is one of the more common varieties. It produces nice white flowers in spring, has a well-structured canopy in summer, and has gorgeous crimson foliage in fall. It grows to 40 feet, plus it's drought-tolerant and deals well with neglect. Another suggestion is Salix matsudana 'Tortuosa,' the corkscrew willow. As its common name implies, the branches twist and spiral, making its brown-gray branches appealing even in winter. It is a fast grower and will reach a height of about 40 feet. The root system grows quickly, too.

If a big burst of spring color is appealing, try a crabapple. There are lots of varieties, allowing for choices in flower color, tree size, flower and canopy shape, and fall-foliage color. One drawback is fruit litter, which may lead to squirrelly visitors unless you keep the area around the tree well raked. You could also consider a large shrub such as the quick-growing peegee hydrangea (Hydrangea paniculata Grandiflora). Not to be confused with the blue and pink pompomlike plants, the peegee hydrangea grows to about 25 feet and produces large white flowers in late summer, turning purplish-pink in fall.

Landscape architect Clara Batchelor of CBA Landscape Architects in Somerville has a few favorite trees for the urban landscape, among them dwarf heritage river birch and star magnolia. She also uses the multi-stemmed shrub Viburnum dentatum as a small tree for urban yards. All of these are shade-tolerant and fast-growing.

I have been offered free wood chips from a tree company. I'd use them as mulch around trees and on my garden path. Is there any reason this is not a good idea? Do wood chips attract termites, for example?
LAURA JEPPESEN /// Newton

Wood chips provide all the services of a good mulch - they keep the soil cool, control weeds, and help soil retain moisture. However, fresh wood chips can tie up important nitrogen reserves and keep them from the plants that the mulch is meant to protect. If you keep the chips on top of the soil rather than incorporating them into the soil, which would raise the likelihood of them becoming a nitrogen drain, this should not be a problem.

As fresh chips decompose, they may also increase soil acidity, possibly raising it to a level your plants may not tolerate. Wood chips can also act as a refuge for unwanted additions to the garden - from mice to molds - and there is a small chance they could carry diseases from their previous lives.

If you use wood chips around trees and on garden paths, you should be fine. Place the chips around the trees to a depth of about 4 inches. Mulch should never be placed directly against the base of a tree, however, as it causes bark problems and interferes with root growth. Instead, form a ring around the tree base. To be safe, test your soil's acidity from time to time. When using the chips on a garden path, keep them away from planting beds so that leaching acids will not affect them.

"Buyer beware" warnings about wood mulch originating from around New Orleans are spreading via the Internet. Many Louisiana trees are infested with voracious Formosan termites, the warnings caution, adding that mulch made from infested trees felled by Hurricane Katrina is being shipped to other parts of the country. Soon bags of termite-laden mulch will be in a store near you at dirt-cheap prices, the warnings assert.

However, there seems to be little cause for concern. While Formosan termites are indeed a problem in Louisiana, that state's Department of Agriculture & Forestry has ordered quarantines on woody debris from hurricane-ravaged parishes. Any such debris must be taken to an approved landfill within the quarantine area. And even if some termite-infected debris were to escape the quarantine, entomologists say the soft-bodied insects would probably not survive the mulching process.

My new amaryllis did not bloom this year during the Christmas holidays. It had plenty of leaves, but no flowers. What could have caused this to happen?
MARYANNE /// Woburn

Amaryllis are a beautiful holiday tradition. A fresh amaryllis bulb should produce one or more large colorful flowers. Lush leaf growth but no flowers may indicate it wasn't "energized" sufficiently, either before your purchase or during its growth. You can keep the bulb and try for blooms next year. After the shoot emerges from the bulb, apply a high-phosphorous fertilizer specifically designed for blooming houseplants once every 10 days to help promote flowering. In the meantime, continue to water and fertilize the plant with an all-purpose fertilizer through the summer. If you like, move the plant, in its pot, to an outside spot where it will get lots of light. This will give the leaves more time to fully develop. In late August, bring the pot inside and discontinue watering. The leaves will die and should be removed. Place the bulb in a dark space for eight weeks, then return it to a well-lighted room and begin to water. If the leaves gathered enough energy during the summer, a flowers talk should begin to grow.

What would you recommend as a starter book or DVD for the beginner New England gardener? I would like advice as to when to order bulbs and plants, the proper time to plant, a listing of perennials and annuals and how they should be cared for, how to organize plants, how to space them, and what to use for soil amendments and fertilizer. TERRY /// Princeton

I use two books that are specific to our region: Northeastern Landscaping and Northeastern Garden Book, both from Sunset Publishing. Both cover gardening and landscaping topics for all of New England, plus New York through Ohio and down to Virginia. Northeastern Landscaping is full of basic information, including garden types, planning, and design, what climates and conditions you'll find, incorporating structures into the garden, and regional pest and landscape issues. It also discusses common plant types (perennials, bulbs, annuals, etc.) and where and how to use them in the garden. Northeastern Garden Book focuses on plants commonly used in this region, listing about 5,000 plants, from bulbs to trees and everything in between, and how to use them. It also has lists of plants for special uses, such as in windy areas, damp soil, butterfly gardens, or for best fall color. I also turn to The Well-Tended Perennial Garden by Tracy DiSabato-Aust (Timber Press, 1998) for tips on how to maintain specific perennials.

My husband and I are in a quandary about the 16 arborvitae shrubs that line our drive-way. They have been in place for 25 years and are pruned yearly to maintain their size and shape. Each plant is about 5 to 6 feet high and 3 feet in diameter. However, they have sustained much winter abuse, and we are thinking about replacing them. We enjoy the privacy they offer and don't want to feel exposed to the street once they are removed. Any suggestions on replacements that would offer the same year-round privacy? JOANNE DOOLEY /// Beverly

Since you appreciate your arborvitae and their attributes, why not replace them with new arborvitae? These are the dependable, nearly indestructible workhorses of the home landscape, and they grow quickly. Once they reach the height you desire, just prune to fit the space. There are not many fast-growing trees that will provide a year-round screen. The longevity of your current plants speaks to their initial quality. I would suggest bypassing the mass merchants and buying your next batch from a quality nursery or garden center. You may pay a little more, but the chances of them surviving are much better.

I received a gorgeous gardenia last Christmas. It looked healthy, with lots of buds but no flowers. As the label directed, I watered it with lukewarm water in my sink when the soil felt dry, which was about every 36 hours, and I misted it several times a day. Even with all the pampering, the plant still didn't produce any flowers. Was the pot too small? It seemed very tight, but repotting a new plant did not seem like the right thing to do. JEFFE MISTRY /// Lynnfield

Your guess at the gardenia's problems is likely correct. The biggest clue: the soil feeling dry after just 36 hours. Properly planted houseplants should not need watering that frequently. The soil should be porous in order to hold air and to provide nooks and crannies that retain moisture. In a pot-bound plant, the root system fills in the microspaces that should hold the much-needed water reserve.

Repot the gardenia in a container at least 8 inches in diameter; use a larger pot if you are starting with a sizable plant. Be sure the pot has drainage holes. A mix of two parts potting soil and one part peat moss should retain an adequate amount of water. Keep the gardenia moist but do not overwater. Since gardenias love humid air, put the plant in a room with a humidifier or place the pot on a tray of moistened pebbles.

Buying a gardenia in flower is a fabulous thing; the blooms have such a wonderful fragrance. Getting a gardenia to flower, on the other hand, is a bit tricky. The plant's temperature requirements make it easiest to try reblooming in spring and fall when nights are cool and days are warm. Ideally, evening temperatures should be about 60 degrees, daytime temperatures about 75. The plant will need bright light for four hours each day but avoid hot, strong midday sun. Once buds appear, a balance of cool nights, warm days, bright (but not overbearing) light, humid air, and lightly moist soil is the key to getting full blossoms. Too much of one thing and not enough of another may cause buds to wither and fall.