Boxwood is a popular and versatile evergreen shrub that adds beauty and elegance to any landscape. However, despite their resilience, boxwood plants can sometimes turn yellow, indicating a problem with their health. Understanding the reasons behind this yellowing can help you address the issue effectively and revive your plants.
Several factors can contribute to boxwood turning yellow. One common cause is nutrient deficiency, particularly a lack of iron or magnesium. This deficiency can result from poor soil conditions or improper fertilization. Another possible reason is excessive watering or poor drainage, leading to root rot and suffocation of the plant. Pests and diseases, such as boxwood blight or spider mites, can also cause yellowing. By identifying the cause, you can take the necessary steps to restore the health and vibrancy of your boxwood plants.
Boxwood shrubs are popular evergreen shrubs known for their rich green foliage However, at times you may notice yellowing leaves on your boxwood plants. This can happen for several reasons and may or may not require trimming. Here’s what you need to know about trimming yellow leaves on boxwood shrubs.
Why Boxwood Leaves Turn Yellow
There are a few potential causes for boxwood leaves turning yellow:
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Fungal diseases like boxwood blight or root rot. These are more likely to cause yellowing when conditions are damp.
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Winter damage. Exposure to harsh winter winds and sun can dry leaves out and cause discoloration.
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Dog urine. Boxwoods are sensitive to the high nitrogen content in dog urine. This can burn and yellow the leaves
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Pest problems. Pests like leaf miners and scale can feed on boxwoods causing yellowing.
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Poor drainage. Wet soil leads to root rot and yellow leaves.
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Salt damage. Road salt spray can dry out and yellow boxwood foliage.
Should You Trim Yellow Leaves?
Whether you should trim yellow leaves depends on the underlying cause:
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If yellowing is due to fungal disease, prune out any infected branches, twigs, or leaves. Disinfect your pruners between each cut. Improving air circulation can also help.
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For winter damage, generally no trimming is needed. The yellow leaves often recover once spring arrives.
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With dog urine damage, prune back damaged sections. Rinse the shrub off to wash away excess nitrogen. Train dogs to avoid the area.
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Pest problems may require pruning off badly infested areas along with pesticide sprays. Promote general plant health.
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Overwatering requires no pruning, just improved drainage and less frequent watering.
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With road salt damage, the only solution is moving the shrub away from the road. Pruning won’t help.
- Prune for disease, dog urine, or pest damage
- Improve growing conditions for winter damage, overwatering
- Move plant for road salt damage
- No pruning needed for winter damage or overwatering
How to Trim Yellow Leaves
When trimming off yellow boxwood leaves or branches is needed:
- Use clean, sterilized pruners to prevent disease spread
- Cut just above leaf nodes or branches
- Remove whole branches if they are more than 50% yellowed/damaged
- Take out only the worst sections, don’t overprune
- Prune in dry weather to limit disease spread
- Disinfect tools after each cut
- Remove and discard all pruned trimmings
- Avoid shearing, promote natural shape
Proper trimming helps maintain the ornamental shape and appearance of the boxwood while removing damaged sections. Combine with fixes for the underlying cause.
When to Trim Yellow Leaves
Time pruning to limit stress:
- Spring or early summer is best, when boxwood is actively growing
- Avoid pruning during hot, dry weather which adds stress
- Prune to maintain shape after new growth appears in spring
- Cut out diseased or pest-damaged branches immediately at any time
- Never prune late fall going into winter
How to Prevent Yellow Leaves
While some yellowing is normal, you can take proactive steps to keep boxwood foliage healthy:
- Choose resistant cultivars
- Prune for shape and air circulation
- Water early, avoid wet foliage
- Use mulch to conserve moisture
- Check for pests routinely
- Keep dogs away from plants
- Move plants away from roads
- Disinfect tools between plants
- Improve drainage in overly wet areas
With proper care and pruning only when needed, you can help your boxwood shrubs retain their ornamental beauty for years to come.
Step 1: Identifying the cause of yellowing
To effectively revive your yellowing boxwood plants, you must first identify the underlying cause of the yellowing. As mentioned earlier, nutrient deficiency, improper watering, and pest infestation are common culprits. Begin by checking the soil pH and conducting a soil test to determine any nutrient deficiencies. Adjusting the soil pH and providing appropriate fertilization can address nutrient-related yellowing.
If the yellowing is due to improper watering, evaluate your watering techniques. Boxwood plants require regular watering, but overwatering can lead to root rot and yellowing. Ensure that the soil drains well and avoid waterlogged conditions. On the other hand, insufficient watering can also cause stress and yellowing. Strike a balance by watering deeply but infrequently, allowing the soil to dry out slightly between waterings.
If pests or diseases are causing the yellowing, take immediate action to control them. Consult with a professional or a local garden center to identify the specific pest or disease affecting your boxwood plants. Follow the recommended treatment methods, which may include pruning affected branches, applying insecticides or fungicides, or removing and destroying severely infected plants. Taking prompt action will prevent further damage and allow your boxwood plants to recover.
Step 3: Treating boxwood yellowing with appropriate fertilization
Proper fertilization is essential for addressing nutrient deficiencies and reviving yellowing boxwood plants. Before applying any fertilizer, conduct a soil test to determine the specific nutrient deficiencies. Based on the test results, choose a balanced fertilizer that contains the necessary nutrients, such as iron and magnesium, to replenish the soil.
When applying the fertilizer, follow the instructions provided by the manufacturer. Be careful not to over-fertilize, as this can lead to nutrient burn and further damage to your plants. Apply the fertilizer evenly around the base of the plants, avoiding direct contact with the foliage. Water the plants thoroughly after fertilization to ensure proper nutrient absorption.
Regular fertilization, typically once or twice a year, will help maintain the health and vibrancy of your boxwood plants. However, be cautious not to overdo it, as excessive fertilization can also cause yellowing and other issues. Strike a balance by monitoring the growth and appearance of your plants and adjusting the fertilization schedule accordingly.
How To Manage Boxwood Dieback
FAQ
What to do when boxwoods turn yellow?
Adjusting the soil pH and providing appropriate fertilization can address nutrient-related yellowing. If the yellowing is due to improper watering, evaluate your watering techniques. Boxwood plants require regular watering, but overwatering can lead to root rot and yellowing.
How to make boxwoods green again?
- First, use disinfected, clean shears to cut back damaged branches. …
- Also, prune the shrub’s center, especially if it’s overly dense! …
- Remember that boxwood shrubs have short, shallow roots. …
- Add a one-inch mulch layer to the soil after watering the plant.
When not to prune boxwood?
Fortunately, boxwoods can be pruned any time but late summer and early fall. This is because pruning then will spur new growth that won’t harden off in time for winter and be killed by the cold.
How do you fix yellow leaves on shrubs?
Leaves that are Yellow, Curling, and Drooping
To fix this, the solution is to water your plant to evenly and thoroughly saturate the soil. Some plants may perk back up within a few hours after watering, while others may require a few days.