Foliar fertilizers for orchids are liquids that are sprayed on the leaves of plants to supplement the fertilizers applied to the soil. Gardeners commonly use them to correct nutrient deficiencies or to provide extra nutrients to boost growth. Since foliar fertilizers contain only small amounts of nutrients, they are not practical for applying the large amounts of the main nutrients needed by orchids.
What’s for Dinner?
In addition to abundant nitrogen, phosphorous, and potassium, orchids need smaller amounts of calcium, iron, magnesium, and sulfur. They also need trace amounts of boron, copper, manganese, molybdenum, and zinc. Orchids need a fertilizer with higher amounts of nitrogen and potassium than phosphorous when they are young and during the growing season of older plants to promote vegetative growth. During the flowering season, orchids need more phosphorous and potassium to encourage more and larger blooms.
Take a Shower
Foliar fertilizers for orchids are available ready-to-use or as a concentrate. If using a conventional fertilizer concentrate, mix one-quarter of the recommended amount with the full amount of water so the solution will not burn the leaves. Add 1 or 2 drops of insecticidal soap or horticultural oil per gallon of foliar fertilizer to help it stick to the leaves. Spray a fine mist on the upper and lower sides of the leaves until the liquid drops off. Foliar fertilizer can also be sprayed on exposed roots. Foliar fertilizers can be applied weekly or bi-weekly, as needed.
And a Bath
Conventional liquid fertilizers can provide large amounts of nutrients to the roots of an orchid, where they are taken up and transported throughout the plant. The fertilizer should be mixed at half-strength and applied once a week. Fertilizers with non-urea types of nitrogen are best for orchids, because the nitrogen is readily available to the plants.
Do not spray fertilizer on orchids in the direct sun to avoid burning the foliage. Do not let water or liquid fertilizer accumulate at the base of the leaves to prevent disease and rot of middle of the plant. Do not continuously feed orchids with a fertilizer for increased flowering, as it will cause the foliage of the plants to grow stunted.