Regarding their habitat, the great majority are epiphytes (grow on the surface of trees), but they can also be classified as rupicolous (grow on rocks), terrestrial (grow on soil) and saprophyte (grow on organic matter). Under natural circumstances, orchids get their mineral nutrition from organic detritus that accumulate near them, such as bird manure, decomposing tree bark and dry leaves, that get moistened from the rain or dew and slowly decompose and release the nutrients needed by the plants.
Despite what some may believe, orchids do not drain any nutrients from the trees they grow on. They develop and bloom in nature as a result of the nutrients found in the environment, therefore, it is safe to assure that they are not very demanding nutrition-wise.
Orchid is also in the i-Plant Nutrition database and can be selected for the creation of fertilizer plans when using the software.
Types of Orchid Fertilizers There are basically two types of fertilizers available for gardening: organic or mineral.
The greatest difference between them is that the organic fertilizer needs to be decomposed by microorganisms that will release the nutrients in the soil solution to be absorbed by the roots. While the mineral fertilizer already offers all the elements that are vital for plant growth in the form of macro and micronutrients.
Also, the mineral fertilizers present the percentage of each nutrient existing in its composition, facilitating the correct dosage, whereas the same organic fertilizers can have quite variable nutrient composition.
Which one to choose depends only on the grower’s preference. Usually, if the orchids are grown indoors, the mineral fertilizers are picked in order to avoid unpleasant odours that may come from the rotting of the organic matter. If the orchids are cultivated in open spaces with good air circulation, organic fertilizers can be a good option, mostly given to their lower application periodicity. Organic Fertilizers Among the organic options to feed orchids, the most popular ones are oilseeds, animal manure, bone meal, wood ash, and bokashi (organic fertilizer obtained from the fermentation of animal and plant origin materials, that besides the chemical elements, also provides microorganisms that are beneficial for the plant). Mineral Fertilizers The plants demand a different ratio of nutrients in each growth stage, and that needs to be considered when deciding which fertilizer to use.
The most common mineral fertilizers used on orchids are usually composed of nitrogen (as long as not in urea form), phosphorous and potassium, known as N-P-K.
During the growth stage of the seedlings, and also in the sprouting and development of buds of adult plants (vegetative phase), the most required chemical element is nitrogen. Forasmuch as nitrogen is responsible for the plant’s vegetative growth. Some NPK formulations used on this stage are 10-5-5, 30-10-10 or the commercial brand Osmocote Classic that has 19-6-12 ratio with a polymer coating called “prill” that allows the slow release of the nutrients.
Once the orchid has developed and also near dormancy, maintenance formulations are recommended. In other words, fertilizers with balanced percentages of N, P and K should be used, such as 10-10-10 or 20-20-20.
When the blooming is near or the plant is shedding new roots, the indicated formulations are the ones that present a greater amount of phosphorous, an element responsible for root growth, disease resistance and for blooming and flowering. For example, 7-9-5, 10-30-20 or 15-30-15.
Besides N, P and K, orchids need other macro and micronutrients, that can also be provided through fertilizer application. MSU, for example, is an orchid fertilizer developed by the Michigan State University with a different composition from the majority of the recommendations, with a 13-3-15 8Ca-2Mg formulation, containing high potassium (in charge of increasing root growth, disease and drought resistance and flower and fruit development) and also provides calcium and magnesium, elements that are very important for the photosynthesis.
By using the i-Plant Nutrition software, it is possible to have access to our wide database of fertilizers and create tailored orchid fertilization plans with the fertilizers the user prefers. Fertilizer application Regardless of the fertilizer origin, orchids absorb nutrients mostly through the roots and in a smaller amount through the leaves, so the application can be in the substrate or foliar.
When using organic fertilizers, the recommendation is to apply every 3 months, on the substrate, as far as possible from the developing roots and new sprouts.
The mineral formulations can be found either in solid or liquid form, and both need to be diluted in water. The applications should be weekly when sprayed on the leaves or every two weeks when applied on the substrate.
Using the correct amount of fertilizers and applying in the right frequency is essential to avoid the salinization of the substrate, paralyzing root growth and the burn of the plant’s aerial parts.
If the orchids don’t receive the nutrients necessary for their survival, they will show signs of deficiency, such as chlorosis, leaf burn, slow development and absence of flowers. By uploading a leaf test in the i-Plant Nutrition, the user is able to get an instant evaluation of the nutrient status of the crop and detect eventual deficiencies.