Proper fertilization is essential for cultivating healthy Crepe Myrtles (Lagerstroemia species), cherished for their vibrant and extended bloom periods. Supplying necessary nutrients supports robust growth, enhances flowering, and contributes to their overall resilience.
Nutrient Needs of Myrtles
Crepe Myrtles require a balanced diet of macronutrients and micronutrients. The primary macronutrients are Nitrogen (N), Phosphorus (P), and Potassium (K), often represented as an NPK ratio on fertilizer labels. Nitrogen promotes lush foliage, phosphorus aids root development and flower production, and potassium contributes to overall plant health and stress resistance.
Myrtles also benefit from various micronutrients like iron, magnesium, manganese, and sulfur. Iron deficiency, for instance, can lead to chlorosis, characterized by yellowing leaves with green veins. The soil’s pH also influences nutrient availability; Crepe Myrtles prefer slightly acidic soil with a pH range of 5.5 to 6.5 for optimal nutrient uptake.
Optimal Fertilization Schedule
Correct fertilization timing is important for the health and bloom production of Crepe Myrtles. The best time to begin fertilizing established plants is in early spring, just as new growth starts to emerge. This initial application provides a strong foundation for the upcoming growing season. A second, lighter application in late spring to early summer, just before the first blooms appear, can encourage heavier flowering.
For newly planted Crepe Myrtles, a different approach is beneficial. During their first growing season, these young plants can be lightly fertilized monthly from spring until late summer. This consistent, lighter feeding helps establish a robust root system. Discontinue all fertilization in late fall to allow the plant to “harden off” and prepare for winter dormancy, preventing new growth that could be vulnerable to cold damage.
Choosing and Applying Myrtle Fertilizer
Selecting the appropriate fertilizer involves considering the NPK ratio and the release type. A balanced fertilizer, such as a 8-8-8 or 10-10-10 blend, is generally suitable for Crepe Myrtles. For gardeners prioritizing more abundant blooms, a fertilizer with a higher phosphorus content, like a 10-15-9 or 10-50-10 ratio, can be beneficial, as phosphorus supports flower development. Slow-release granular fertilizers are often recommended because they provide a steady supply of nutrients over several months, reducing the need for frequent applications.
When applying granular fertilizer, scatter it evenly around the plant’s drip line, which is the area beneath the outermost branches. Avoid placing granules directly against the trunk, maintaining a distance of at least 6 to 12 inches from the base to prevent potential burn. After scattering, gently work the fertilizer into the top layer of soil, then water the area thoroughly. For container-grown myrtles, liquid fertilizers applied every few weeks can keep them thriving. Always follow the specific instructions on the fertilizer product label for appropriate dosage, as amounts vary based on the product and plant size.
Troubleshooting Common Fertilization Issues
Incorrect fertilization can lead to several problems, but recognizing the symptoms allows for timely intervention. Over-fertilization, especially with too much nitrogen, can cause excessive leafy growth at the expense of flowers, or even lead to “fertilizer burn.” Symptoms of fertilizer burn include brown leaf tips and edges, yellowing, or wilting leaves, and sometimes a visible crust of fertilizer salts on the soil surface. To address this, removing the top layer of soil and flushing the area with heavy watering can help leach out excess salts from around the roots.
Conversely, nutrient deficiencies manifest with distinct signs. Yellowing leaves with green veins, known as interveinal chlorosis, often indicate an iron or manganese deficiency. This can occur if the soil pH is too high, making these micronutrients unavailable. Poor blooming or stunted growth can also signal insufficient phosphorus or an overall lack of balanced nutrients. Soil testing can identify specific deficiencies or pH imbalances, guiding adjustments to fertilizer type or soil amendments to restore plant health.