So, you’ve picked up a tree from a London garden centre or out here at our London nursery, and now it’s time to plant it.
If you want your trees to be healthy and achieve their proper size, they need enough space above and below ground. Most trees want soil that is 3 feet deep.
That doesn’t mean you have to dig 3 feet down, just that it’s best not to plant on soil that is solid rock a foot down, or water-logged a foot down, and so on.
And trees need a wide space, too. I see the landscaping departments of many garden centres in London planting trees in a very small area. But if the trunk will mature at 1 foot wide, it really needs 200-300 square feet of soil space. If 2 feet wide, it needs 500-600 square feet.
Of course, they need space above ground, too. I’ve seen thousands of trees planted too close to buildings and other obstacles.
So what this means is you must place your trees as far away from hardscaping and buildings as you can, including the swimming pool, septic system, retaining walls, and hydro wires. It also includes the sidewalk and driveway.
I go with a minimum of 10 feet when possible. Roots can grow under a sidewalk and driveway, but it’s not ideal – for them or the hardscaping, which will inevitably get cracked. Plus, the trunk flare needs plenty of room to develop properly.
Trees can be spaced quite close together, though. If you plant trees close at 10 to 20 feet apart, it will encourage them to go more upright, which is actually more natural for them. It will provide a better canopy and decrease the need to prune branches that would otherwise be too low if the trees were planted further apart. And trees are actually happy to be planted in clusters.
Trees for a hedge can go even closer. Coniferous trees are often used for this. I’ve planted them as close as 3 feet apart, trunk to trunk, but if the client doesn’t mind waiting a little longer for privacy, I prefer to give the trees 5 feet to allow them a little more room.