Oleander (Nerium oleander) is a hardy, drought-tolerant shrub known for its vibrant blooms and glossy foliage. From a plant's perspective, oleander thrives in well-draining soil with balanced nutrients. It requires nitrogen (N) for leafy growth, phosphorus (P) for root development and flowering, and potassium (K) for overall health and disease resistance. Micronutrients like iron, magnesium, and calcium are also essential for chlorophyll production and cellular function.
Oleanders respond well to slow-release granular fertilizers or liquid fertilizers. A balanced formula, such as 10-10-10 or 14-14-14, ensures equal parts of nitrogen, phosphorus, and potassium. For enhanced blooms, a fertilizer with higher phosphorus content (e.g., 5-10-5) can be applied during the growing season. Organic options like compost or well-rotted manure also provide gentle, long-term nourishment.
Oleanders benefit from fertilization in early spring as new growth emerges. A second application in mid-summer can support prolonged blooming. Over-fertilizing can lead to excessive foliage at the expense of flowers, so moderation is key. In warmer climates, a light fall feeding may be beneficial, but avoid late-season fertilization in colder regions to prevent tender growth before winter.
Oleanders prefer slightly acidic to neutral soil (pH 6.0–7.0). If the soil is too alkaline, iron and other micronutrients may become less available, leading to yellowing leaves (chlorosis). Adding sulfur or organic matter can lower pH, while lime raises it. Regularly testing soil pH ensures optimal nutrient uptake.
Container-grown oleanders have limited soil volume, so they require more frequent fertilization. A diluted liquid fertilizer every 4–6 weeks during the growing season works well. Ensure pots have drainage holes to prevent salt buildup, which can damage roots. Flushing the soil with water occasionally helps remove excess salts.
Yellowing leaves may indicate nitrogen deficiency, while poor flowering suggests low phosphorus. Brown leaf edges can signal potassium shortage. Conversely, excessive nitrogen causes lush foliage with few blooms. Adjust fertilizer type and dosage based on these visual cues to maintain plant health.
For gardeners preferring organic methods, fish emulsion, bone meal (for phosphorus), and kelp meal (for potassium) are excellent choices. Compost tea provides a gentle nutrient boost and improves soil microbial activity. These options release nutrients slowly, reducing the risk of over-fertilization.
Proper watering ensures nutrients dissolve and reach the roots. Water deeply after fertilizing to prevent root burn and distribute nutrients evenly. Avoid overhead watering to minimize fungal diseases, which oleanders are prone to in humid conditions.
