Ideal Fertilizer Ratio for Orchids
The orchid family (Orchidaceae family) encompasses a huge array of plants in soil-bound North American natives to exotic, tree-dwelling tropicals. With varieties hardy from U.S. Department of Agriculture plant hardiness zones 3 through 12, orchids differ considerably from each other yet share similar nutrient requirements. A balanced, complete fertilizer, such as 20-20-20, provides excellent orchid nutrition in maintaining American Orchid Society recommendations.
Proper orchid nourishment is uncomplicated. Like all plants, orchids need nitrogen, phosphorus and potassium in the biggest amounts. These primary macronutrients are the three numbers on fertilizer packaging — always in the same order. Nitrogen (N) fuels green, leafy growth. Phosphorus (P) enhances root growth and flowering, and potassium (K) facilitates overall growth and wellness. Fertilizers that include all three of these essentials are called whole fertilizers. Products with three matching numbers contain equal proportions of these nutrients and are called balanced fertilizers. Complete, balanced nutrition facilitates all of the basic facets of orchid development.
Some specialty orchid fertilizers adapt nutrient ratios for different stages of orchid development. Additional nitrogen facilitates powerful, fresh shoots, while phosphorus and potassium add extra boosts as plants flower or develop origins. These specialty fertilizers are available in a variety of ratios, but all build on a whole, balanced foundation. With bark-grown orchids, like moth orchids (Phalaenopsis spp., USDA zones 10 through 12), bark decomposition may reduce available nitrogen. A whole, 30-10-10 fertilizer offers extra nitrogen for all these plants. Nitrogen delivered in the kind of urea frequently tucked away. Non-urea fertilizers supply orchids with a more successful source, as stated by the American Orchid Society.
Timing and Rates
Orchids’ sensitive origins are vulnerable to fertilizer burn. Less is best. Year-round weekly feedings of all one-fourth-strength fertilizer are preferable to full-strength, monthly feedings for many orchid types. Water orchids with unfertilized water first, and completely wet the origins and growing medium. Then water with a diluted fertilizer solution. For example, dissolve 1/4 tsp of water-soluble, 20-20-20 fertilizer in 1 gallon of water water pre-watered mix well. Fertilize native ground-dwelling orchids, like slipper orchid (Cypripedium kentuckiense, USDA zones 3 through 8), from spring during the flowering season using the same diluted solution.
Salts from fertilizers or water itself can build up in orchid containers over time. The telltale white crust on bark, fiber or orchid origins shows orchids have been overfertilized or never watered before fluid applications. Salt buildup steals moisture and chemicals fertilizer burn. Sensitive orchid origins also react to chemicals and minerals in water added to fertilizers. Avoid softened water and mineral-heavy well water, which can damage orchid roots. Allow chlorinated tap water to sit overnight before applying. Captured precipitation or reverse-osmosis water flushes salts away and dilutes fertilizers without adding harmful salts. Use room-temperature water for fertilizer solutions.