I own and operate a small tree farm. I also grow containerized fir and spruce trees. I have been growing them in dirt (top soil), which makes them heavy and hard to manage. I bought some material from a local nursery to plant them in, and whatever they mix together killed all 200 of the trees. They claimed I planted them wrong. I don't think so, only a few of the ones in the soil didn't survive. Can someone tell me what I should be growing my trees in? I start with 2-2's in 5-gallon pots.
Container Spruce and Fir Trees
Certified GKH Gardening Expert
You should be using a soilless mix of some kind for the containers. Plain soil can compact and make it hard for the plants to grow. That being said, it is hard to say what killed the plants without having been there to see the potting mix. It is possible that if the nursery mixes their own, they had too much fertilizer.
But, I would not give up on potting soil. Make sure that when you first use it to plant the trees that the soil is completely wet, and do not allow it to dry out completely. A down side of potting mix is that if it becomes dry or is not wet enough, it will actually repel water when watered normally. You need to soak it in a bucket or tub of water to get it to re-wet if this happens.