Lavender, a fragrant herb from the sun-drenched Mediterranean, brings unique beauty and aroma to any garden. It thrives in conditions where many other plants struggle, preferring rocky, nutrient-poor soil. This native habitat dictates a minimal approach to feeding. Understanding the plant’s preference for lean soil is the first step in determining the right fertilization strategy.
Understanding Lavender’s Low-Nutrient Preference
Lavender prefers lean, well-drained, and slightly alkaline soil, ideally with a pH between 6.5 and 8.0. This preference stems from its origins in dry, harsh climates where nutrients are naturally scarce. The plant evolved to thrive on minimal resources, making it susceptible to problems caused by over-fertilization.
The biggest danger comes from fertilizers high in nitrogen (N), the first number in the NPK ratio. Too much nitrogen encourages excessive vegetative growth, resulting in floppy, weak stems and lush green leaves. This happens at the expense of flower production and the plant’s characteristic fragrance. High nitrogen also reduces winter hardiness and makes the lavender more vulnerable to fungal diseases and root rot.
Choosing the Right Fertilizer Blend
When selecting a fertilizer, the goal is to provide trace minerals and support flowering without forcing excessive leaf growth. This requires a product with a low-nitrogen, higher-phosphorus (P), and potassium (K) profile. A suitable NPK ratio is often found in blends like 5-10-10 or 0-10-10, where the phosphorus and potassium numbers are equal to or greater than the nitrogen number.
Phosphorus (the middle number) promotes strong root development and overall plant vigor. Potassium (the third number) supports robust flowering, water management, and resistance to environmental stress. Organic options naturally suited to this profile include a light application of bone meal or kelp meal. Using a slow-release granular product formulated for flowering shrubs is an effective way to deliver these necessary nutrients gradually.
Application Timing and Technique
Lavender generally requires only one, or sometimes two, light applications of fertilizer per year. The best time to feed the plant is in early spring, just as new growth is beginning to emerge from dormancy. This timing ensures the plant has the necessary resources to support the season’s flowering cycle.
For lavender grown in pots, a very light second feeding in early summer may be beneficial to replace nutrients lost from regular watering. Apply the fertilizer sparingly around the plant’s drip line, which is the area beneath the outer edge of the branches. Gently scratch the granular product into the surface of the soil and water lightly to help absorption. Avoid applying fertilizer directly onto the foliage or the base of the stem, as this can cause burning or encourage crown rot.