How To Plant a Mature Tree

Planting a mature tree can dramatically change the look of your landscape overnight, providing immediate shade, beauty, and value to your property. This Old House landscape contractor Roger Cook demonstrates how to plant a large pear tree in a residential front yard.

Choosing the Right Planting Location

Location matters. You want to pick a spot where the tree will get the sun and rain it needs to thrive, as well as nutrient-rich soil conditions. Keep the tree away from your house, driveway, and other structures to prevent potential damage as it grows and its roots extend. Also ensure that the tree won’t interfere with overhead or underground utility lines.

You may want to position flowering trees where you can enjoy seeing them from inside or where you want a pop of color on your property. Or, plant trees where you want shade or privacy. 

Expert Insight: This Old House landscape contractor Roger Cook advises thinking about purpose first: “If it’s to create shade, you’ll want one with a broad, leafy canopy. On the other hand, if you’re trying to screen out the neighbors, you want upright evergreens that can be grouped together to block the view.”

Preparing the Tree Planting Site

Once you’ve chosen the ideal location, you’ll need to prepare the planting site.

• Use a small sledgehammer to drive a stake into the ground, indicating the center of the tree hole.
• Extend a tape measure from the center stake to mark the radius of the tree hole. For most mature trees, opt for a hole that’s deep enough to accommodate the tree’s root ball while keeping the tree’s root flare slightly above ground level and about three times as wide. 
• Create a circular outline on the ground following the measured radius.
• Use a pointed spade to cut along the circle, slicing through grass and roots to create a clean edge.

Pro Tip: When sizing your planting hole, This Old House landscape contractor Roger Cook uses a helpful rule of thumb: “My rule of thumb is for every inch of trunk, I want 10 inches of root ball.” Measuring the trunk diameter first helps you gauge the root ball size and plan the right hole dimensions.

Digging the Hole for the Tree

With the site prepared, it’s time to dig the hole for your mature tree. This step requires heavy machinery to handle the size and weight of a large root ball.

Using an Excavator

Protect the surrounding area by laying down plastic mats to keep your lawn and driveway safe from damage caused by the excavator. Dig the hole according to the perimeter you made earlier. Remove any rocks and pay attention to the soil composition as you dig, noting any changes in color as you reach the subsoil layer.

If the existing soil is poor, mix in some high-quality topsoil or compost to improve drainage and nutrient content.

To determine exactly how deep to dig, let the tree itself guide you. Carefully remove soil from the top of the root ball to expose the root flare — the point where the trunk begins to widen and the first roots emerge. Measure the height from the bottom of the root ball to that flare, and dig the hole to precisely that depth. The only way to accurately confirm the measurement is to pull a string line across the top of the hole and measure down to the bottom. When you replant, the root flare should sit right at grade level.

Planting the Mature Tree

A hydraulic tree spade is invaluable for this task. It can carefully lower the tree into the prepared hole, handling the significant weight of a mature tree and its root ball.

Lower the tree into the prepared hole with the tree spade. Shovel soil around the tree spade blades to about halfway up the spades.

Use a garden hose to saturate the soil around the tree spade. This helps settle the soil and eliminate air pockets. Slowly retract the tree spade blades, ensuring the tree’s position remains stable.

After planting the tree, cut and remove any twine or ties wrapped around the tree’s branches. Fill in any remaining gaps around the tree with soil. Create a small berm around the low side of the tree to help contain water during irrigation.

Sprinkle a granular root stimulant around the base of the tree and rake it into the soil. Give the newly planted tree a deep watering to help it establish in its new location.

Caring for a Newly Planted Mature Tree

Proper care in the weeks and months following planting is crucial for the tree’s long-term health and survival.

Watering

Water deeply 2–3 times a week for the first few months, then gradually reduce to once a week as the tree establishes. Provide about 10 gallons of water per inch of trunk diameter each time you water. Using a slow-release watering bag or soaker hose ensures deep, even watering.

Mulching

Apply a 2–3 inch layer of organic mulch around the base of the tree, extending to the drip line. Keep the mulch a few inches away from the trunk to prevent moisture buildup and potential rot.

Fertilizing

Wait at least one year before fertilizing to allow the tree to establish its root system. Use a slow-release, balanced fertilizer specifically formulated for trees. Apply fertilizer in early spring before new growth begins.

Pruning

Avoid heavy pruning for the first year to allow the tree to focus energy on root development. Remove only dead, damaged, or crossing branches as needed. We suggest hiring a certified arborist for major pruning tasks on mature trees.

Pro Tip: In a This Old House project episode, the landscaping expert outlined a specific watering schedule for newly planted trees: “I want you to water it every day, the first week, twice a week, the second week, and then once a week, every week after that up until the ground freezes.” This tapering approach helps the root system gradually adapt to drawing moisture on its own.

Transplanting Techniques for a Mature Tree

Transplanting mature trees involves advanced techniques to ensure minimal stress on the tree and its survival in the new location.

Timing and Weather Conditions

Choose the right time of year for transplanting, usually late fall or early spring when the tree is dormant. Ensure weather conditions are favorable, with no extreme heat or cold.

Tree Preparation

Before transplanting, water the tree thoroughly for several days so it’s well-hydrated. Prune any dead or overgrown branches to reduce the tree’s overall mass and ease the transplant process.

Moving the Tree

Use a tree spade or other heavy machinery to carefully dig out the tree, ensuring a large enough root ball to support the tree in its new location. Transport the tree carefully to avoid damaging the trunk and branches.

Expert Insight: Kimberly Hiren of Groundworks Landscaping advises that a successful transplant “depends on having an intact root ball of sufficient size — about 11 times the trunk’s diameter. If the trunk is more than 3½ inches across, call in a professional landscaper because of the weight involved.”

Monitoring Tree Health 

After planting or transplanting, monitor the tree’s health weekly. Look for signs of stress, such as yellowing leaves, wilting, or slow growth. Address any issues promptly to ensure the tree’s long-term health, enlisting an arborist if needed.

Pest and Disease Control

Regularly inspect the tree for pests and diseases. Treat any infestations promptly with appropriate methods, such as organic pesticides or professional pest control services.

Soil and Nutrient Management

Test the soil around the tree monthly to ensure it has the right nutrient balance. Adjust soil composition as needed with compost, mulch, or fertilizers to support optimal tree health.