Ask Mr. Smarty Plants

First, we had to determine what were your average first and last frost dates. From a website on Oswego County, we learned you had already had a temperature of 25 deg. on October 19. You appear to be in Zone 5b in the USDA Hardiness Zone Map, which means your average annual minimum temperatures can range from minus 10 deg to minus 15 deg.  From a Cornell University Gardening Resources site, Last Spring Frost in Northern New York, we found out your last average frost date is from April 10 to April 20.We believe that small new plants need all the chances they can get to survive, and having to face a blast of frigid air when they are freshly planted and still suffering from transplant shock probably reduces their chances considerably. We will consider each tree you asked about separately, but we feel the verdict on all of them is going to be the same-plant them after your last average freeze date in the Spring, April 10-20, and they will have a much higher survival chance.

All of these trees are native to North America, as well as to New York State. We are always happy to see our correspondents selecting trees native to North America and to the area in which they are being grown. They are more adapted to conditions and will need less fertilizer, water and maintenance. Follow each plant link to our webpage for information from our Native Plant Database and then the other links giving more planting and culture information. 

Thuja occidentalis (arborvitae) - Plants are susceptible to strong wind, snow, and ice damage, and young plants need protection from winter browsers. It's not bad enough they get their little branches frozen, but they get nibbled, perhaps to the ground, before they ever have a chance. More information from University of Connecticut Horticulture Thuja occidentalis

Pseudotsuga menziesii (Douglas-fir) - grow naturally in New York, foliage consumed by grouse, deer and elk. More information from University of Connecticut Horticulture Pseudotsuga menziesii

Picea pungens (blue spruce) - native to New York, for more information see this article from Virginia Tech on Blue Spruce. Pictures

Thuja occidentalis

Pseudotsuga menziesii