Q: I recently purchased a Douglas fir, about one foot tall. What do I do next for best growth?
A: This will be a daunting task! Douglas fir is best adapted to the northwestern US, in Hardiness Zones 4-6. We live in the warmer Hardiness Zone 7. Our hot, humid summers are not easy for a Douglas fir to tolerate. I think it would be happier if planted outdoors now.
This is my best advice: choose a site that gets morning sunshine and afternoon shade. The site should have a slight slope, to help water move away from the roots. Use a shovel to loosen the soil twelve inches deep in a planting area eight feet across. Remove one third of the soil in the area and replace it with gritty sand, such as paver leveling sand or granite dust.. Thoroughly mix it into the soil. If the soil is mostly clay to begin with, mix in four cubic feet of soil conditioner. After planting, water deeply once each week for a year, particularly during the summer. Following these steps will give you at least a fifty percent chance that your fir will survive for a decade or more.