Boxwoods are popular landscape plants, valued for their dense, evergreen foliage and versatile forms. They provide structure and year-round interest in many gardens. To ensure boxwoods remain healthy, vibrant, and dense, proper nutrition through fertilization is important. This supports their natural growth and helps them resist environmental stressors.
Why and When to Fertilize Boxwoods
Fertilizing boxwoods offers several benefits for their health and appearance. Adequate nutrition promotes lush, dense foliage, enhances their vibrant green color, and supports robust growth. A well-nourished boxwood is also better equipped to withstand disease and pest infestations.
The optimal time to fertilize boxwoods is in early spring, just before new growth begins. This ensures essential nutrients are available as plants enter their active growing phase. Fertilizing too late in the growing season, particularly late summer or early fall, can stimulate tender new growth. This new growth may not harden off before cold temperatures, making it susceptible to frost damage, which can lead to browning and plant stress.
Choosing the Right Boxwood Fertilizer
Selecting an appropriate fertilizer is important for boxwood health. A balanced fertilizer, such as a 10-10-10 N-P-K ratio, is often suitable. However, boxwoods benefit from formulations slightly higher in nitrogen for lush foliage growth, like a 10-6-4 N-P-K ratio. Nitrogen is essential for green color, phosphorus supports root development, and potassium aids overall plant health. Conducting a soil test can determine specific nutrient deficiencies and pH levels, guiding the most effective fertilizer choice. Boxwoods prefer a soil pH between 6.5 and 7.0, though they tolerate 5.5 to 7.5.
Slow-release granular fertilizers are recommended for boxwoods due to their shallow root systems. These formulations release nutrients gradually over several months, minimizing fertilizer burn and providing a steady supply of nutrition. This controlled release prevents an excessive surge of nutrients that can harm sensitive roots. While liquid options provide quick nutrient absorption, granular slow-release products are easier to apply evenly and offer consistent feeding.
For organic options, well-aged compost or well-rotted manure serve as excellent soil amendments and nutrient sources. Organic fertilizers release nutrients slowly as they decompose, improving soil structure and microbial activity. Blood meal is another organic choice that provides a nitrogen boost. Organic fertilizers may require more frequent application than slow-release synthetic options, perhaps two applications per season, as their nutrients typically break down within 6 to 8 weeks. Avoid fertilizers designed for acid-loving plants like azaleas, as these can lower the soil pH too much for boxwoods.
How to Fertilize Boxwoods
Before applying fertilizer, water the boxwood thoroughly. This ensures the soil is moist, helping the plant absorb nutrients and reducing the risk of root burn. Always follow the manufacturer’s instructions for recommended dosage, as rates can vary.
For granular fertilizers, spread the product evenly around the base of the shrub, extending to the drip line (the area beneath the outermost branches). Boxwood roots can extend beyond this, so covering a wider area ensures nutrients reach active feeder roots. Avoid direct contact between granules and the trunk, stems, or foliage, as this can cause leaf scorch or tissue damage. If mulched, apply granular fertilizer directly on top of the mulch. After application, water thoroughly to dissolve granules and move nutrients into the root zone.
Liquid fertilizers require dilution according to product instructions and are typically applied by drenching the soil. Over-fertilization can be detrimental, causing leaf discoloration, wilting, stunted growth, and fertilizer burn from excess salts. If these symptoms appear, reduce or temporarily halt fertilization. Starting with a conservative amount and gradually increasing based on plant response and soil test results is a safer approach.