Giant Green Arborvitae Spacing

Getting the spacing right for your giant green arborvitae is the single most important decision you make at planting time. This guide will walk you through the proper planting distance for these popular evergreens, ensuring your hedge or screen grows thick, healthy, and beautiful for decades to come.

Planting them too close leads to a world of problems, while spacing them too far apart wastes time and money. Let’s make sure you get it perfect the first time.

This specific variety, often sold as ‘Green Giant’ (Thuja standishii x plicata ‘Green Giant’), is famous for its rapid growth and lush foliage. Understanding its mature size is the key to unlocking correct spacing. A common mistake is to plant based on the small size you buy from the nursery.

Why Spacing is Non-Negotiable

Proper spacing is about giving your trees the resources they need to thrive. Crowded plants compete fiercely, and the loser is always your landscape.

Here’s what happens with incorrect spacing:

Disease & Pest Havens: Poor air circulation creates a damp, humid environment. This invites fungal diseases like blight and attracts pests.
Stunted Growth & Dead Zones: Roots and branches become entangled. The lower and inner branches, deprived of sunlight, will brown and die, creating an irreversibly thin base.
Nutrient & Water Competition: Their root systems will fight for every drop of water and bit of soil nutrition, stressing all the plants.
Increased Maintenance: You’ll be forced to prune constantly to manage size, which is an uphill battle against their natural growth habit.

The Golden Rule: Mature Width Dictates Spacing

A mature Giant Green Arborvitae typically reaches 12 to 15 feet in width. This number is your guiding light for all spacing calculations. Always plan for the full mature size, even though it may take 10-15 years to get there.

Spacing for a Classic Privacy Hedge or Screen

For a dense, seamless hedge where the trees will grow together to form a solid green wall, spacing is closer. The aim is for the trees to just kiss as they mature.

Plant each tree 5 to 8 feet apart, measured from the center of one trunk to the center of the next.
For the fastest screen, 5-6 feet is common. If you have more patience and want slightly less pruning, opt for 7-8 feet.
A single straight-line row is almost always best for a hedge.

Spacing for Standalone Specimen Trees

If you want each tree to maintain its distinct, natural pyramidal shape without growing into its neighbors, you need more room.

Space them 12 to 15 feet apart center-to-center.
This allows each tree to showcase its full form and ensures sunlight reaches all sides.
This is ideal for property borders, windbreaks, or accent planting where a solid wall isn’t the goal.

Step-by-Step Planting Guide

Once you’ve marked your spacing, proper planting ensures success.

Dig the Hole: Make it 2-3 times wider than the root ball, but only as deep as the root ball is tall. Planting too deep is a major cause of failure.
Prep the Root Ball: Gently loosen any circling roots on the outside. If the tree is pot-bound, you can make a few shallow vertical cuts down the sides.
Position the Tree: Set it in the hole so the top of the root flare (where the trunk widens) is slightly above the surrounding soil grade.
Backfill: Use the native soil you dug out, unless its pure clay or sand. Amend it lightly with compost if needed. Tamp the soil gently as you fill to remove large air pockets.
Water Deeply: Create a soil berm around the edge to form a watering basin. Soak the entire area thoroughly to settle the soil.
Mulch: Apply 2-3 inches of organic mulch (like shredded bark) around the tree, keeping it a few inches away from the trunk itself.

Beyond the Basics: Pro Tips for Success

Considering Rows and Property Lines

If planting multiple rows for a extra-thick screen, stagger the trees in a zig-zag pattern. Space the rows themselves 10-12 feet apart. Always check your local setback ordinances—you must plant trees several feet inside your property line, not directly on it. Account for the mature 15-foot spread when calculating this.

The First Two Years are Critical

Your arborvitae’s number one need is consistent water while they establish. They have a relatively shallow root system. Deep watering once or twice a week is far better than frequent sprinkles. A soaker hose is a great investment for a new hedge.

Hold off on fertilizer at planting time. You can apply a balanced, slow-release fertilizer in the second spring if growth seems slow.

Common Spacing Mistakes to Avoid

Ignoring Utility Lines: Always call 811 before you dig to have underground utilities marked. Plant trees well away from overhead power lines.
Forgetting About Buildings: Plant at least 8-10 feet away from foundations, driveways, and sidewalks to allow for mature growth and prevent root damage.
Underestimating Growth: That 3-foot sapling will be 20+ feet tall and wide. Trust the mature dimensions, not the nursery pot.
Neglecting Future Access: Leave space between the hedge and a fence for maintenance, or between trees and your house for painting and repairs.

FAQs About Arborvitae Spacing

How far from a fence should I plant Giant Green Arborvitae?

Plant the tree so its center is at least 7-8 feet from the fence line. This gives it room to grow to half its mature width without pressing against the fence, allowing for air flow and maintenance on your side.

Can I plant them 4 feet apart for an instant screen?

You can, but you will regret it. They will fill in faster initially, but within 5-8 years they will be overcrowded. You’ll face increased disease risk, dead lower branches, and constant heavy pruning. Patience with 6-8 foot spacing pays off long-term.

What if my arborvitae are already planted too close?

If they are still young (under 5 years), you might be able to carefully transplant some to a new location in early spring or fall. If they are established, your only option is aggressive annual pruning to manage size, or removal of every other tree to improve spacing for the ones that remain.

How fast do they really grow?

Giant Green Arborvitae are remarkably fast, adding 3 to 5 feet in height per year under ideal conditions until they start to near there mature height. This rapid growth is why correct initial spacing is so crucial—problems develop quickly.

Do I need to stake them after planting?

Generally, no. These trees are sturdy and staking can prevent the trunk from developing natural strength. Only stake if you are in a very windy site, and use loose, flexible ties that you will remove after one growing season.

Taking the time to measure and plan your giant green arborvitae spacing is an investment. It saves you countless hours of labor, money on replacements, and the disappointment of a failing hedge. By giving them the room they need from the start, you’re setting the stage for a lifetime of lush, healthy, and beautiful greenery that will provide privacy and structure to your garden for many years to come. Remember, the best hedge is one you can plant and mostly enjoy, not constantly struggle with.