Whatever your garden needs, leave it to trees

A tree can be the biggest object in your garden, both in terms of impact and of cost. Think carefully about not only the kinds of trees you select, but also where you put them in the garden.

Along with the hardscape — paths, terraces, fences and garden shelters — trees form the bones of the garden.

When placing them, think first about what you want them to do. One of their most important functions is to give scale to a design.

True, you could have a garden without the overstory that trees provide, using a prairie as a model, and our own native forests can seem to be made up only of trees.

But most of us are comfortable with a mix of trees, shrubs and low plants, and the sunny and shady conditions that the mixture provides.

Screening is an important function. Small trees such as crabapples will serve in place of a hedge to block out a neighbor's house with foliage in the summer and a haze of bare branches in the winter.

Or choose small evergreen trees that won't need the pruning that a hedge does, such as slender hinoki cypress (Chamaecyparis obtusa 'Gracilis') or mountain hemlock (Tsuga mertensiana), a Northwest native conifer. Even though it is an alpine tree, it does well in our lowlands and won't grow to towering heights like many of our other native conifers.

If you like your view, frame it with trees on either side. Heighten borrowed views by repeating conifers seen beyond the bounds of your garden with large or small ones in your own garden.

If your garden is not so spacious, the small conifers mentioned above would work well, as would many dwarf conifers that take years to reach even 10 feet.

Consider trees for the shade they give. Reduce the heat load on your home in the summer by placing them to the south or west. Choose deciduous trees that will let in the winter sun. Plant a tree to shade a terrace or deck and create a sheltered spot for outdoor living.

Well-placed trees will anchor a garden composition. Place them so the plan swoops up to crescendos at selected points, linked by lower shrubs and perennials. The variety in height adds excitement.

Add interest, too, with contrasts in leaf texture and color. Plant a dramatic deciduous specimen such as tall stewartia (Stewartia monodelpha) against a neutral background of evergreens to accentuate the summer flowers, fall color and intriguing winter bark of the stewartia.

Selecting a tree requires vision. Be aware how large a plant will grow, and then imagine it in your garden. Consider carefully the ultimate size of the tree. Trying to keep a big tree small can be expensive, and you will never win. The tree loses, too, because topping a tree promotes weak, unhealthy new growth.

Viewing trees

For a list of trees that do well in our climate and information on how tall they grow, visit the City of Seattle Web site at www.seattle.gov/transportation/treeplanting.htm#recommend. The list is intended for trees on planting strips but also is handy in selecting trees for anywhere in the garden.

Another place to view trees is at a nursery. Wandering the rows, you may discover trees you've never heard of, and find one perfect for your garden. Ask for guidance if you want your tree to do double duty, such as providing fruit, fall color or fragrance.

Unusual trees may not be available in large sizes. A small tree, however, will catch up with a larger one. Sometimes you may decide that you want immediate gratification and only a large tree will do; in that case, seek out a nursery with large specimens.

Trees should be one of the first investments you make in your garden. The sooner you put that tree in the ground, the sooner you will get results and have the satisfaction of watching it grow.

When you plant a tree, it is not just for you; it is a gift for the next generation.

Phil Wood has a degree in landscape architecture and designs and builds gardens. Call 206-464-8533 or e-mail thegardendesigner@seattletimes.com with your questions. Sorry, no personal replies.