The pineapple plant (Ananas comosus) is a tropical perennial with a long growth cycle, often spanning 18 to 24 months. It is a heavy feeder, requiring sustained nutrition to produce healthy, sweet fruit. Choosing the right fertilizer and applying it correctly is crucial for achieving optimal growth, fruit size, and sugar content. Successful cultivation depends on adjusting the feeding program to match the plant’s specific needs at each stage of development.
Essential Nutritional Requirements
The pineapple plant’s nutritional program centers on the three macronutrients—nitrogen (N), phosphorus (P), and potassium (K). Nitrogen supports the constant production of leaves needed before flowering. A deficiency results in stunted growth and the yellowing of older leaves, while an excess can delay fruit maturity and reduce sugar content.
Phosphorus is important for root development, but the plant’s requirement for it is significantly lower than for the other two macronutrients. Potassium is needed in the highest amounts, improving fruit weight, shape, and sugar content. Yellow spots on the leaves often signal a potassium deficiency.
Beyond the NPK trio, the plant requires several micronutrients, most notably magnesium, iron, and manganese. Iron is crucial for preventing the yellowing of young leaves, especially in alkaline soils. Foliar sprays containing zinc and manganese should be applied periodically, as a zinc deficiency can cause a condition known as Crookneck.
Recommended Fertilizer Formulations
Pineapple plants thrive on a consistent supply of balanced fertilizer, emphasizing nitrogen and potassium. General NPK ratios range from 6-6-6 to 10-10-10, though ratios higher in potassium, such as 10-5-10 or 8-4-8, better reflect the plant’s needs as it matures. Since pineapples preferentially absorb nitrogen as ammonia, ammonium sulfate is often an effective nitrogen source.
For slower-release options, dry granular mixtures are recommended, typically containing 6% to 10% of NPK, along with 4% to 6% magnesium. Organic alternatives include compost and well-rotted manure, supplemented by liquid options like fish emulsion or compost tea applied via foliar feeding. The fertilizer solution should be complete, often including manganese, zinc, and iron, and mixed carefully to avoid burning the leaves.
Timing Fertilizer Application
Fertilization timing must align with the pineapple plant’s distinct growth phases. For the first 14 to 16 months, the focus is on vegetative growth to produce a vigorous plant capable of supporting a large fruit. During this establishment period, fertilizer should be applied frequently in small amounts, typically every 6 to 8 weeks.
Nitrogen and potassium are generally applied in multiple split doses, sometimes up to six times during the growing season. Phosphorus, which is needed less frequently, is often applied entirely during the vegetative stage. This frequent feeding ensures a steady nutrient supply for the plant’s continuous leaf production.
The most important timing adjustment occurs as the plant approaches the reproductive stage and flowering is induced. Nitrogen fertilization must be significantly reduced or stopped entirely about two months before bloom induction. Once flowering occurs, fertilization should continue to enhance fruit quality, but avoid spraying fertilizer directly onto the developing inflorescence to prevent injury.
Practical Application Techniques
Pineapple plants are uniquely adapted to absorb water and nutrients through their leaves, making foliar feeding the most efficient application technique. The crescent shape of the leaves forms a rosette, allowing the plant to collect and absorb a liquid fertilizer spray. In large-scale operations, 75% to 80% of nitrogen, along with significant portions of phosphorus and potassium, is applied via foliar sprays.
When using liquid fertilizers for foliar feeding, the concentration must be carefully calculated to prevent chemical burn on the leaves. The total fertilizer content in the solution should generally not exceed 10%. A mild solution of the nutrient mix is sprayed directly onto the leaves, and applications can be made every 8 to 10 weeks.
For granular or dry fertilizers, the application method is known as side dressing. The fertilizer is applied to the soil around the base of the plant, approximately 5 cm away from the central crown. Keep granular fertilizer off the leaves and out of the central cup to prevent tissue damage or heart rot from caustic salts. Always water the plant thoroughly before and after applying dry fertilizer to dissolve the nutrients and minimize the risk of root burn.