I am going to be planting 2 pear trees and another apple tree, all dwarf varieties. What should I plant under them? Are there good companion plants? I live in Beaverton, OR.

You can plant members of the umbelliferae family (carrots,etc) as they host the parasitic wasp which kills apple maggot. They also attract positive pollinators.
john S
PDX OR

I would personally not plant anything under my apple trees, as they would be competing for water and nutrients, but since you do live in oregon its probably ok because there is certainly plenty of water. I'm in southern california where its mostly dry and I like to separate my plants. hope they grow and blossom well.

There's not generally plenty of water in Portland in the summer (once we're finally out of the rainy season, which we seem to be). But you'd be watering the underplanting anyway, so just water those carrots better than you usually would, and everything should be fine. I've tossed carrot seeds under my larger apple tree, and never seen a one, so I can't comment on how well it works. I've probably weeded them out ruthlessly, along with the rest of the mess.

Here are some companion plants put in Piper's Orchard, which is an old orchard we are showcasing in a Seattle Park.

http://pipersorchard.org/gardening-guid ... -planting/

(you may have to type in link if you can not click it).