How to Plant a City Street Tree

In this video, This Old House landscape contractor Roger Cook brings a bit of green to the concrete jungle.

Mindy Maslin of the Pennsylvania Horticultural Society, which has been “the leading force in tree planting, gardening, everything green and beautiful in the region” since 1827, joined Roger to plant street trees as part of their Plant 1 Million initiative across Pennsylvania, Delaware, and New Jersey. As Maslin notes, street trees do more than add character — deciduous varieties create shade to cool buildings in summer, then drop their leaves in winter to let the sun’s rays warm them.

Planting a city tree:

1. Use pointed shovel to dig out old, dying tree. Shovel dirt onto plastic tarp.
2. Set new tree into hole and stretch a string across hole to determine planting depth. Be sure root flare isn’t buried below ground.
3. Gently tug on roots to ensure they’re not twisted together or bound around the root ball.
4. Be certain the tree is perfectly straight, then backfill around the root ball with soil. Use your hands to pack soil into air pockets.
5. As you continue to shovel dirt around the tree, fill the planting hole with water from a garden hose to compact the soil.
6. Drive two 2×2 stakes into the ground and then secure the tree with two straps.
7. Spread 3 inches of licorice-root mulch around the tree, but don’t pile any mulch against the trunk.
8. Water tree twice a week for two weeks and then once a week until ground freezes. Water with garden hose, slow-drip irrigation bag, or 5-gallon bucket with drip holes drilled around base.

When digging the planting hole, make it at least two times the root ball’s diameter with a flat bottom. Stop digging when the hole is slightly shallower than the depth of the root ball, measured from where the trunk’s base flares out. If the flare is buried, unwrap the ball and pull away soil and roots to expose it.

Pro Tip: Roger, This Old House landscape contractor, stresses the importance of precise hole depth: “Exactly 16 inches, not a bit deeper. We want that root flare planted right at grade.” He adds that the only way to accurately measure the depth of the hole is to pull a string line across it.

Licorice-root mulch is especially good for putting nutrients back into the soil. When watering, another option is a slow-release irrigation bag: zip it into place around the trunk, insert your hose into the pocket, and fill it with 15 gallons of water that will slowly release into the tree pit. If you prefer a simpler approach, a five-gallon bucket with small nail holes drilled around the base works just as well—fill three buckets for each watering session.

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