By Joel M. Lerner
Post
Saturday, May 21, 2005; F11

It's time to answer some of your questions about gardening. This is, after all, the season.

Q Can you tell me what to do with daffodils once they're done blooming? -- Heidi Phillips

AThe bulbs should be allowed to "season" undisturbed until the leaves turn yellow. Do not fold foliage in half, braid or clean up their appearance in any other way. Then dig, divide and move, or simply cut foliage. Most daffodils in well-drained places will increase in numbers annually and naturalize into an area, returning for years, since wildlife doesn't eat them. Fertilizer is not necessary. Organic material is a plus when transplanting. Transplant deeply, six to eight inches, in soil rich in compost.

Bamboo continually invades my yard. What material is best for a barrier? How deep should it go, and should it jut out of the ground? -- Steven Wertime

We have mowed, hacked and grubbed bamboo out of yards. Even though it will still invade, you can slow the uncontrolled run of bamboo with edging and perhaps send the roots in another direction. Here is one method that will result in fewer shoots popping up in your yard.

Get a trencher from an equipment rental company and, staying outside the drip lines of nearby trees, cut a trench at least 18 inches deep. Install edging made of a continuous run of some material that roots won't grow through, like plastic, steel, aluminum or concrete. We have used aluminum roofing flashing, and I have clients who used steel and deep concrete curbing. The key is to maintain a continuous run. Let it stick out of the ground at least three to four inches.

The cryptomeria japonica "Elegans Nana" that I replaced last year died. The first one lasted several years but turned progressively browner and eventually died. It was the perfect plant for that location, especially because the deer did not seem to like it. Given that two successive plants have died, I am hesitant to replace it with another cryptomeria. Do you have any suggestions? -- Howie Wilpon

Cryptomeria japonica is a tough plant that is fairly easy to grow -- in the right environment. It must have good air circulation, sunlight and moist, extremely well-drained, acidic soil. This compact, slow-growing shrub gets about three feet tall and wide at maturity and would still be my first choice, with proper soil amendments, such as digging in compost and a liberal amount of chicken grit to lighten the soil. Here are some other suggestions for plants to fit your space that deer supposedly won't eat:

· Hybrids of boxwood ( Buxus microphylla ): Fine slow growers reaching 24 to 36 inches in about as many years are Kingsville dwarf, pincushion, winter gem, green pillow, green gem and green mound.

· Globose blue spruce ( Picea pungens "Glauca Globosa"): Rounded habit, grows to three feet, then forms a flat top.

· Dwarf yaupon holly ( Ilex vomitoria "Nana"): Low-growing, small-leafed evergreen.

· Bluebeard ( Caryopteris X clandonensis ): Dies to the ground in winter but flowers on new growth.

· Gold mop threadleaf falsecypress ( Chamaecyparis pisifera "Gold Mop"): Low-growing golden evergreen foliage.

The only evergreens for full sun that are a fairly sure bet are boxwoods, blue spruce and cryptomeria. However, as deer herds increase, they could develop a taste for them, too.

I have four healthy English boxwoods, each about four feet in diameter, which are getting too big for their planted site. I would like to prune them to a three-foot diameter. Can this be done? -- Newman deHaas

They can be renewal pruned by cutting them back during their dormant period in late winter, before growth begins. If you cut the entire plant back hard to mostly bare stems, it can take three years before they are full again. The way to prune them and maintain ornamental value is to cut the longest stems, making them two to three feet tall. Prune only about one-third of the plant, leaving holes in the boxwood where they will begin to renew on the inside. The following year, prune about a third of the longest stems again; do the same the next year. By then, they will be well on their way to becoming bushy plants at whatever size you have trained them. Always keep your plants full by pruning them to grow wider on the bottom than on the top, allowing the sun to reach the entire plant.

What are the advantages and disadvantages of English boxwood vs. American boxwood? -- Harold M. Hagen

English boxwood refers to one hybrid, or cultivar, of common boxwood ( Buxus sempervirens "Suffruticosa"). It matures, in a century or more, at a height of three to five feet. It can also be kept to several inches in height because of the slow growth habit. This is the boxwood seen throughout Europe as low edging plants.

The American boxwood ( Buxus sempervirens ) is a misnomer, because it is the same species as English boxwood -- a native to southern Europe, northern Africa and western Asia. Usually American boxwood refers to the numerous cultivars that have been bred from the species. Many of those referred to as "American" are larger, faster-growing plants, up to 15 to 20 feet.

They are all susceptible to the same insect and disease problems. The cultivar "Suffruticosa" is considered more resistant to boxwood leaf miner than others.

My house is surrounded by English ivy. I'm thinking about getting rid of it. However, it appears that almost all of it is dead or dying. Should I be worried about the trees? -- Bernis Abes

English ivy is mildly susceptible to several leaf fungi that would pose no threat to your trees and shrubs. It usually recovers rapidly, unless it gets a lot of foot traffic or deer browsing. My guess is that it will recover, and in short order, dominate again. If that's the case, you can remove it by doing one small area at a time. It will roll back and can be pulled out of the ground. Then till the soil, digging up the remaining ivy, trying not to tear tree roots. To avoid any impact on beneficial plants, cover the ivy with landscape fabric, held down with soil staples. Leave the ivy covered for one full year to kill it and lift the fabric next spring to till the roots and stems.

I'm curious about the evergreen trees that look like corkscrews or the ones that have pompons at the end of the branches. How often do they have to be pruned, and how should it be done? Are there specific varieties that lend themselves to such treatment? -- Margaret McInturff

The shrubs, usually evergreens, are trained by shearing them into those shapes. This style of pruning is called topiary. Evergreens that are good candidates for topiary are junipers, yews, boxwoods, arborvitaes, leyland cypresses and hollies. Many have been shaped from a young age. Plants should be located where they get sunlight around the entire plant and proper soil preparation. The shape you choose -- bear, chair, pompom, corkscrew -- will determine how often you need to prune.

Generally, one to three prunings a year are needed. Pruning is usually done with a sharp hand shears after the shrub has pushed its new growth in spring. If there are large holes or areas that need to be renewed, you might want to prune in late February to early March, before growth begins. Shrubs with large leaves can be shaped, but it is better to hand-clip them to avoid tearing the leaves. Shaping smaller foliage can be done with manual or electric shears. All pruning should be done carefully, stepping back often to check your lines and make sure that you are keeping the form you want.

More complex shapes, such as animals, are often trained by planting inside a wire form and clipping the shoots as they grow outside the wire boundary. Unless you are creating a topiary garden, the plants you describe are better used as a sculptural element on your property and displayed as a single specimen or two at a sunny front entry or in a garden room.

To see examples of topiary in this area go to Ladew Gardens in Monkton, Md., north of Baltimore ( http://www.ladewgardens.com ).

Joel M. Lerner is president of Environmental Design in Capitol View Park, Md. E-mail or contact him through his Web site,http://www.gardenlerner.com.