Planting a new 6-foot arborvitae is an exciting step towards enhancing your landscape, whether for privacy, a windbreak, or simply evergreen beauty. However, the success and longevity of this investment hinge significantly on one crucial factor: the planting hole. Many gardeners focus solely on the size of the plant above ground, neglecting the critical role of the subterranean environment. Digging a hole that is either too small or incorrectly shaped can stifle root growth, lead to waterlogging, or even cause the plant to fail altogether. This article will delve into the precise measurements and techniques required to prepare the perfect planting site, ensuring your 6-foot arborvitae establishes robust roots and flourishes for years to come.
Understanding the root ball and why hole size matters
Before you even pick up a shovel, it is essential to understand the nature of your 6-foot arborvitae’s root system. A plant of this size will typically come in one of two forms: either balled and burlapped (B&B) or in a large container. In both cases, the root ball represents the existing network of roots and the soil immediately surrounding them. For a 6-foot specimen, the root ball might have a diameter ranging from 18 to 28 inches and a similar height, though these can vary. The primary goal of digging the hole is not just to accommodate this existing root ball, but to provide an ample, inviting space for new roots to expand outwards into the native soil.
The mistake many make is digging a hole that is just barely wide enough for the root ball. This creates an immediate barrier for root expansion. When roots encounter compacted, unworked soil directly at the edge of the planting hole, they often struggle to penetrate it, sometimes circling within the loosened soil, leading to a condition known as “girdling.” Furthermore, the depth of the hole is equally critical. Planting too deep buries the root flare, the point where the trunk widens at the soil line, which can lead to rot and suffocation of the essential surface roots. Planting too shallow, while less common, can expose roots to drying out and frost damage.
The ideal hole dimensions: width and depth demystified
For a 6-foot arborvitae, the ideal hole dimensions are dictated by the size of its root ball, with a clear emphasis on width over depth. To promote healthy root development, the planting hole should be *two to three times the width* of the root ball. This generous width provides a wide zone of loosened soil, allowing new roots to easily spread out laterally into the surrounding landscape. If your arborvitae’s root ball is, for example, 24 inches in diameter, your hole should be between 48 and 72 inches wide.
When it comes to depth, precision is paramount. The hole should be dug so that the top of the root ball is level with, or slightly above (by 1-2 inches), the surrounding grade. This ensures that the critical root flare remains exposed and allows for any anticipated settling of the soil. Never dig the hole deeper than the height of the root ball. If you accidentally dig too deep, add soil back to the bottom and compact it firmly to prevent the plant from settling too low over time. Here’s a general guide:
| Root Ball Diameter (approx. for 6′ Arborvitae) | Ideal Hole Width | Ideal Hole Depth |
|---|---|---|
| 18 inches | 36-54 inches | 18 inches (or root ball height) |
| 24 inches | 48-72 inches | 24 inches (or root ball height) |
| 28 inches | 56-84 inches | 28 inches (or root ball height) |
Preparing the hole and surrounding soil for optimal growth
Once you’ve determined the correct dimensions, the next step involves preparing the soil within and around the hole. The soil removed from the hole is typically the best material for backfilling, especially if it’s native soil. Avoid amending the backfill soil with excessive organic matter unless your native soil is extremely poor (e.g., pure sand or heavy clay) and even then, only sparingly. A common misconception is that amending the backfill heavily benefits the plant; however, it can create a “perched water table” effect, where water drains differently inside the amended hole than outside, leading to soggy roots. Furthermore, roots may become reluctant to grow beyond the rich, amended pocket into the surrounding native soil.
Before placing the arborvitae, gently loosen the soil at the very bottom of the hole, especially if it’s compacted. For the sides of the hole, it’s beneficial to rough up the edges using your shovel. This prevents the formation of a glazed, impenetrable surface that roots might struggle to penetrate. If your soil has poor drainage, you might consider mounding the soil slightly, planting the arborvitae with the root ball slightly above grade and then backfilling to create a gentle slope away from the trunk. This encourages water to drain away rather than pool around the roots.
Proper planting techniques and post-planting care
With the hole prepared, it’s time to place your 6-foot arborvitae. Carefully remove the plant from its container or, if B&B, remove burlap and wire basket materials from the top 1/3 to 1/2 of the root ball. Position the arborvitae in the center of the hole, ensuring the root flare is at or slightly above the finished soil grade. Step back and check for straightness from several angles. Once satisfied, begin backfilling with the native soil you excavated earlier. Gently firm the soil around the root ball to remove large air pockets, but avoid compacting it excessively, as this can impede root growth. Do not bury the root flare.
After backfilling, create a small soil berm or “water ring” around the outer edge of the planting hole. This helps to temporarily hold water, directing it towards the root zone during initial watering. Water the arborvitae deeply and thoroughly immediately after planting. This helps to settle the soil around the roots and eliminates any remaining small air pockets. Finally, apply a 2-4 inch layer of organic mulch (such as wood chips or shredded bark) over the entire planting area, extending out to the drip line, but keep it a few inches away from the trunk. Mulch helps retain soil moisture, regulate soil temperature, and suppress weeds, all critical for the successful establishment of your new arborvitae.
Successfully planting a 6-foot arborvitae begins and ends with meticulous attention to its subterranean needs. The most critical takeaway is to prioritize a wide, rather than excessively deep, planting hole, ensuring it is two to three times the diameter of the root ball. Precision in depth is equally vital, with the root flare positioned at or slightly above the surrounding soil grade to prevent suffocating the crucial surface roots. By utilizing native soil for backfill, avoiding over-amending, and gently firming to eliminate air pockets, you create an optimal environment for robust root expansion.
Immediate, thorough watering after planting, followed by the strategic application of an organic mulch, are the final steps that secure your arborvitae’s healthy start. These practices conserve moisture, regulate soil temperature, and protect the developing root system. By adhering to these guidelines, you’re not just digging a hole; you’re laying the foundation for a vibrant, resilient, and long-lived arborvitae that will enhance your landscape for many years. Proper planting is an investment in your plant’s future, ensuring it has every opportunity to thrive.
Image by: Justice Fleming Attachie