Dawn Redwood seen at the National Arboretum. (Adrian Higgins/THE WASHINGTON POST)
Gardening columnist

If you’re going to plant a tree, is it right to agonize over the choice?

I hope so, because I have been wringing my hands for weeks over what to plant in the location of a big old tree that recently came down. Its absence has changed the light conditions of a large portion of the garden, which might not be a bad thing.

Not all fallen trees must be replaced — that’s the first choice. A disappearance might offer the chance to grow sunny perennials or carve out a vegetable garden.

In this instance, a new tree is needed, to frame a view and to add green architecture to a huge void. Of course, I want it as well for its interest and beauty.

Picking a tree is easy; picking the right tree is far more difficult, especially if you want to plant a conifer, as I do. Unless you live in the higher elevations north and west of Washington, this area is tough on conifers. Many of them aren’t equipped for our infernal summers, which seem to be getting worse.

So strike off the list Douglas fir, concolor fir, Fraser fir, Colorado blue spruce, the larch, the golden larch, Austrian pine — the list expands in every direction.

Now that the Leyland cypress has been discredited for its size and vulgarity, the fast-growing screening conifer of choice has become the Green Giant arborvitae. This isn’t a bad tree — it holds up in winter storms and its foliage is not offensive — but there are other, more handsome choices.

Green Giant is one I gladly dismiss, although others that I have cast off are harder to let go. I like conifers that are deciduous; they tend to have muscular red-brown bark and stunning fall color, which is why it is a shame the golden larch is so unhappy south of the Mason-Dixon line. The dawn redwood is a bigger tree, quite at home here, and its fall show this year was superb, the color of fresh copper. If you race to the National Arboretum’s conifer collection, you might see the last of the show in the groves of mature dawn redwoods. Check out one of several cultivated varieties, including Waasland, a compact and upright variety better suited to smaller gardens.

But I have dawn redwoods at home, and the site in question is too dry for this moisture-loving conifer and its native look-alike, the bald cypress. The cryptomeria would be a great choice, tall, green and fine-textured, but I have three already.

The China fir is a novel conifer whose coarse, spiky needles suggest something truly primeval — such as those of the monkey puzzle tree — but it is hard to find and too narrow for my needs.

In my conifer quest, I visited Tom Moseley, who has spent more than three decades raising conifers at his nursery west of Potomac, Maryland Gardens Tree and Shrub Farm.

He is a fan of Norway spruces (which have been around since Colonial days — perhaps they have earned their naturalization by now) but I think they suffer from overuse, get bigger than most people anticipate and can look ragged in old age.

Firs generally don’t work in Washington, but Moseley is a big fan of the Nordmann fir, which is most commonly used as a cut Christmas tree in these parts. His youngish specimens look happy, and to me seem so much classier than the Norway spruce. The needles are stouter and showier, and display their silver-gray undersides to great effect. But I’m not sure I’d want to risk it, given the trajectory of our climate.

I came close to picking the Oriental spruce, which is as finely textured as the Norway spruce but darker, and with tighter branches that produce a much more elegant outline. “To a novice, they don’t look that different, but to those in the gardening business, they look a lot different,” Moseley said, showing me an eight-foot specimen. They grow more slowly, which always increases the cost for a given size.

As nice as that spruce is, I have consulted my inner tree and realize that I have a hankering for a pine. A pining?

The native Eastern white pine is big and pretty, but it is a creature of the mountains and can suffer in the hot, wet clay soil of the city. It also drops its lower branches after a decade or two, defeating its purpose as a screen. Moseley says that once that happens, you you can plant boxwood or holly underneath them.

If I had a wet spot I might try the longleaf pine, extremely handsome in youth (aren’t we all?), a plant of the deep South and home to the rare red cockaded woodpecker.

But I am drawn to the ornamental qualities of two exotic species that, if you have the room, make fabulous specimens.

The first, the Korean pine, is lovely in all stages. It has long and conspicuous gray-green needless and in time forms a loose pyramid outline with branches that sweep down to the ground. No need for boxwood or hollies.

The second is the one I ended up getting: a Himalayan pine, whose long, silver-green needles hang down in a fine-textured grace. This is a big and broad pine, and has no place in a small urban yard. But in the sweeping expanse of the suburban yard, it can make a lovely lawn specimen. You can see a mature tree at the National Arboretum: After many decades in the sun and unimpeded by neighbors, it has reached about 50 feet in height and 40 feet across.

As an aside, have you noticed how beautiful the ginkgo trees were this fall? The immaculate, bright yellow leaves never seemed more intense. The tree is, like the conifers, a gymnosperm that has remained essentially unchanged over millions of years.

As Hugh Johnson writes in “The World of Trees,” “One feels a certain respect for a creature which has simply declined to evolve.”

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Read past columns by Higgins.