Things change. While we often think we know the best way to do things in the garden, new research is always disproving some of the old wisdom.

Things change. While we often think we know the best way to do things in the garden, new research is always disproving some of the old wisdom.

So if you want to add trees to your landscape, what is the best way to plant them?

"When you plant a tree," says retired forester Tal Blankenship, who serves on the board of the Oregon State University Land Steward Program, "the hole should be saucer-shaped — no deeper than the root ball or the pot it is planted in, but about three times as wide as the root ball."

Blankenship gets his information from the International Society of Arborists, which is continuously researching how best to care for trees. Trees get most of their sustenance from fine roots in the top 3 inches of soil. The majority of roots will go no deeper than 12 inches.

Not adding amendments to the soil is controversial, with many local tree services still believing it gets them off to a better start. Blankenship is in the "no amendments" camp, feeling that you want the tree to acclimate to the soil it is going to live in.

Chad Clark, a certified arborist with Chad's Tree and Landscape Inc. in Medford, agrees with Blankenship.

"If you add amendments to the soil, you could get some girdling because when the roots reach the original soil, they will turn back and follow the nutrient-rich soil," he says. "Using the native soil to refill the hole is much better than spoiling them."

Once you get your tree home, it must be kept moist until planted. Put it on the north side of a building, out of direct sunlight, and cover the roots with wet burlap. Or put it temporarily in a pot full of wet potting soil if it arrives bare-root.

The part of the trunk that flares out into roots must be planted even with the surrounding ground level or an inch or two above. It is important not to bury the root flare.

Fill the hole very carefully, straightening by filling in one side at a time. Press firmly to make sure there are no air pockets among the roots.

Don't stake a tree unless absolutely necessary. Studies show trees develop stronger trunk and root systems if they are not staked .

"You don't want to plant any tree that won't stand by itself," says Blankenship. "It's probably root-bound (if it won't).

"Once you plant it, you want to protect it from animals and people." Blankenship recommends putting a circle of fencing around it for the first year or two.

The best thing you can do to help the plant get started is mulch. Put mulch 3 inches deep and 6 to 12 inches away from the trunk out to the drip line. Keeping it away from the trunk will prevent the growth of fungus and rot.

Blankenship says mulching with the same leaves is best. Maple leaves for maple trees, oak leaves for oak trees, etc. The leaves carry the exact formula of nutrients the tree needs, and if the goal is to replicate the natural conditions of a tree, then mulching with its own leaves is the best thing, though chipped wood of the same tree also works. If you must use some mixed leaves, make sure no walnut or black walnut leaves are included, as they are toxic to many other plants.

"Most people overfertilize and overwater, and their trees become stressed and sickly," says Blankenship.

He recommends taking a large screwdriver and making a hole under the tree with it. Stick a finger in the hole, and if you can feel moisture, the tree doesn't need watering. He says this is much better than a timed drip system because our weather is so variable.

If you follow these rules, your landscape tree should become strong and healthy.