The boxwood shrub is a common evergreen used widely in landscaping for its dense, deep green foliage. Noticing widespread browning, bronzing, or premature leaf drop is alarming, but these signs of decline do not automatically mean the shrub is lost. The following steps provide a practical diagnostic process to determine whether your boxwood is still viable and what actions to take next.
Visual Signs of Distress
A healthy boxwood presents a uniform, deep green color with tightly packed foliage. The first indication of a problem is a noticeable shift in this appearance, usually manifesting as widespread discoloration. This distress often begins with the leaves turning pale yellow, progressing to a straw color or a reddish-brown bronzing across the canopy.
The discoloration is frequently accompanied by a lack of new, bright green growth at the branch tips. The plant may also shed its leaves prematurely, leading to sparse patches and visible twiggy growth within the shrub. These visual cues warn of stress from issues like drought, winter burn, or disease. Because many different problems can cause these symptoms, a physical examination is necessary to confirm viability.
Performing the Scratch and Snap Test
The most reliable way to check for life beneath the bark is by performing the scratch test. This simple diagnostic procedure targets the cambium layer, the living tissue responsible for transporting water and nutrients. Using a clean fingernail or a small knife, gently scrape away a tiny section of the outermost bark on a branch that appears dead.
If the tissue immediately beneath the scraped bark is bright green, moist, or creamy white, the branch is alive and the transport system is functional. Conversely, if the exposed tissue is brown, dry, or brittle, that specific section of the branch is dead. Perform this procedure on several branches, starting at the tips and working back toward the center of the shrub.
The scratch test is often paired with the snap test, which evaluates the wood’s moisture content and flexibility. Select a small, pencil-thin branch and attempt to gently bend it. A live branch will be pliable and bend without breaking due to its internal moisture. A dead branch will be desiccated and dry, causing it to snap cleanly and easily with little resistance. This combination of tests helps confirm viability across different parts of the shrub.
Interpreting Results: Death Versus Dormancy
The findings from the scratch and snap tests distinguish between temporary stress and complete death. If branch tips snap easily and show brown tissue, but the scratch test reveals green tissue closer to the main trunk, the plant is still alive. This localized dieback is common, often resulting from environmental stressors like winter burn or drought, where outer foliage is damaged but the main structure survives.
Boxwood blight or other fungal issues can cause sector-specific dieback, meaning only one side or section of the shrub may show dead tissue while the rest remains green. In these cases, the plant is still viable, and the damage is not systemic. A truly dead boxwood will show brown, dry, and brittle tissue on the scratch test all the way down the stem to the soil line and across the entire structure.
Post-Diagnosis Actions
Once the diagnosis is complete, specific actions can be taken to either remove the dead shrub or begin the rehabilitation process. If the scratch test confirms that all tissue is brown and dry across the entire plant, the boxwood is confirmed dead and should be dug out and removed. Before planting a replacement, investigate the cause of death, checking for issues like poor soil drainage (which encourages root rot) or the presence of boxwood blight.
If the diagnosis indicates the boxwood is stressed or partially alive, the first step is to prune out all the dead wood identified by the tests. Pruning should be done by cutting the branch back to a point just below where the cambium layer first showed green tissue. Following pruning, the plant will benefit from proper cultural care, such as a deep, thorough watering, especially if drought was a factor. Avoid applying heavy fertilizer, as this can stress the plant further; instead, focus on providing consistent moisture until you observe evidence of new growth.