From our perspective, our growth and blooming are intrinsically tied to the seasons and the sun. We are sun-worshippers at our core. Our period of active growth and flowering coincides with the warm, long days of late spring through summer. This is when our demand for nutrients is at its peak. As the days shorten and temperatures drop, we enter a period of dormancy. Applying fertilizer during this dormant phase is not only wasteful but can be harmful, as it may spur tender new growth that will be killed by the cold, weakening us for the next season. The ideal time to begin feeding us is in early spring, just as we break dormancy and you notice the first signs of new leaf buds swelling. This initial nutrient boost supports the development of strong vegetative growth, which will later support our prolific blooms.
To produce our large, vibrant flower clusters, we have specific nutritional needs. While we require a balance of macro and micronutrients, the ratio of these elements is crucial for directing our energy. A fertilizer with a higher middle number in the N-P-K ratio is ideal. Look for a formulation such as 5-10-10 or 10-20-20. The phosphorus (the middle number) is vital for promoting strong bud development, flowering, and root health. The potassium (the last number) supports overall plant vigor and disease resistance. While nitrogen (the first number) is necessary for healthy green growth, too much will encourage us to produce an abundance of leaves at the expense of flowers. A balanced, slow-release shrub and tree fertilizer is also an excellent choice, as it provides a steady supply of nutrients that aligns with our natural pace of consumption.
How you deliver these nutrients is just as important as what you deliver. Our root systems are extensive but prefer to feed in the area just beyond our drip line (the point on the ground directly below the outermost reaches of our branches). The most effective method is to broadcast the recommended amount of granular fertilizer evenly over this soil area and then water it in deeply. This deep watering is critical; it dissolves the fertilizer and carries it down to our root zone where we can absorb it. It also prevents the salts in the fertilizer from accumulating near our surface roots, which can cause root burn. Always ensure our soil is moist before fertilizing; applying fertilizer to dry soil can cause severe damage to our delicate root hairs.
We are not heavy feeders compared to some flowering plants. For maximum blooms, a consistent but modest feeding schedule is best. A single application in early spring is often sufficient to support a full season of growth and flowering. In poorer soils or for container-grown oleanders, a second application in mid-summer can be beneficial to replenish nutrients and sustain blooming into the fall. However, it is imperative that you cease all fertilization at least six weeks before the first expected frost in your area. This allows us to naturally slow our growth and begin hardening off for winter. Fertilizing too late invites tender new growth that is highly susceptible to frost damage, jeopardizing our health.
