Hi, I've been training my bay tree since it was a foot high. It's now 5 feet in height. A double ball tree in a container. I take it out during the summer and keep it indoors during the winter.

As for your tree:
As it is growing now, keep a few stems from the top intact and remove any remaining stems growing below it -- keeping the trunk clean looking. To keep it growing straight tie the trunk to a straight stick loosely using raffia. As the lead stem grows taller and produce more branches at the top, remove some of the lowest branches from the trunk - keeping the number of stems to a minimum. Repeat this every now and then when the plant goes into a growth spurt(it does this periodically -usually towards the end of summer). It will take up to nearly 3 years for it to get to 4 feet. Tie it to the trunk as it grows to keep it straight. Loose the ties when the trunk grows too thick, otherwise it will scar the trunk.

When the lead stem reaches the height you desire, chop off the top. It forces new branches to grow out the sides. When the sides start to grow out to a few inches (say 5") pinch off the tips for force new growth from it's sides. Continue doing this to new growths and keeping in mind the shape you desire.

This is great information.

Would the same techmiques apply to an acrocona spruce, please?

Thanks