Hello Jeffrey.

Thank you for your question.

Organic wood mulch should be great for your spruce trees.

I am unaware of any requirements for type of wood so I’d say go for the aesthetic and/or price range that works for you.

Aside from this, the application of mulch does matter.

It is prudent to avoid piling up mulch too close or too high near the trunk as this can cause damage to the tree’s health.