Trees or bushes that grow to 6-10m mature height
I'm wanting to plant some trees or bushes along a 12m fence line and would like a minimum height of 6m for screening, up to about 10m at full mature height. Ideally I would like trees/bushes that have a spread of 4-6m. I need something that's fast growing, is suited to clay and loamy soil, and has a light canopy. I would really like something that has colourful leaves or pretty flowers, however I have never done any gardening before so most of all I need like something that's low maintenance. With regards to the trunk, I would like something that can be pruned up to fence height, so 1.8m from the ground. As I have young kids I don't want anything that are poisonous. My youngest is one so still has a tendency to put things in his mouth. Thanks for any help.