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How to Grow: Grammatophyllum Orchid Care

Updated: Feb 5, 2022

General Information

The generic name Grammatophyllum is derived from the Greek words gramma, meaning "a mark or character," and phyllum, "a leaf." This probably refers to the varied markings on the petals and sepals of the flowers, which resulted in Grammatophyllum frequently being called the "Letter Plants." The species produce several racemes, arising from the base of the pseudobulb, with many yellow-green to olive-green, waxy flowers with dark purplish-red marks. This epiphytic genus occurs in the dence rainforest from Indo-China to Indonesia, the Philippines, New Guinea, and the Southwest Pacific Islands.

grammatophyllum orchid care india

There are two distinct growth forms in this genus. The first has very long pseudobulbs, resembling sugar cane, bearing many leaves, arranged distichous. The second has rather short thick pseudobulbs which are not covered leaf bases and bear a few leaves around the top of the pseudobulbs. The pseudobulbs are sympodial in growth, with each new growth arising from the previous growth. The flowers of most Grammatophyllum Species are generally yellow and brown.

Grammatophyllum Orchids are not only the biggest Orchids in the world, they’re the Fastest-Growing Orchids

Light Requirements

Grammatophyllum grows well in moderate light intensity. Morning sun is best, until about noon. Observation of the leaf structure can be your best guide to the correct light conditions for which a type is particularly suited. The conditions are similar to Dendrobium and Cattleya, which means that 60-80% of sunlight.

grammatophyllum care light requirement
Optimal Colouration Indicating Sufficient Sunlight

Lime green-coloured foliage is an indication of proper light. Dark green foliage, while very attractive, is not conducive to the plant reaching its full blooming potential. Yellow-coloured foliage indicates too much light. In very mild climates, most members of this can be grown out of doors, with protection from the hot summer sun, and the colder nights of winter. A light green leaf with just a hint of yellow indicates the maximum amount of sun the plant can take, and a dark green leaf indicates not enough sun.

Temperature Requirements

Grammatophyllum will tolerate considerable summer heat as long as they get cool, mild night temperatures between 10-18 °C. Cold weather, even down to minus 2°C for a few hours each night, will not damage an acclimatised plant, but once the plant spikes or flowers, it should be protected from such low temperatures. Regardless, plants should always be kept free of frost. The ideal annual temperature range for most members of the genus Grammatophyllum are 24 to 30°C during the day and 13 to 16°C at night. At higher temperatures, air circulations and humidity must be increased, or damage can occur.

"The Higher the Temperature, the Greater the Plant's need for Humidity"

Water Requirements

Grammatophyllums enjoy frequent watering, during their growing period, but will not tolerate wet feet for extended periods. However, when growth is completed, a 2 or 3 week rest period should follow to allow the growths to mature. Generally speaking, the growing season extends from March to October. The frequency of watering is relative to the container, the temperature, air circulation, and the amount of water retained in the medium in the container. Watering should be done, so the roots are approaching dryness before re-watering. In the warmer periods, several watering a week can be done, without worry, if the roots can dry quickly. Require plenty of water and high humidity during the growing season. All species come from distinct wet/dry habitats. Less water is required during the cooler months.

"The roots are sensitive to fertilizer salt build-up, so clear water flushes are necessary for good growth"

We suggest watering every third day or twice a week during the hot summer months(not suitable for mounted plants). They should not be allowed to go completely dry, yet they don't care for a soggy environment either. We suggest watering once a week in the winter and early spring months when the weather is colder. Lesser the media, more frequent should be the watering.

After you have watered your orchid, it is really important to make sure that the plant is well-drained on regular intervals and to ensure that the roots are not left standing in water for long. The roots won’t tolerate this and can result in root rot if you do.

Humidity Requirements

Grammatophyllum love warm and very humid weather. The humidity level should be at least 50% or higher. Increase the amount of humidity in the summer months. This can be done by misting on the surrounding area or letting stagnant water far below the plants (in its natural habitat it gets morning dew that gathers in a pool on the branches of trees and if you notice the roots are tiny light-colored but multiple, it absorbs the water and stores it in the large bulbs for dry spells). Make sure the plants have good air circulation. This will help prevent fungus, insect problems, and mold from forming on the leaves.

watering grammatophyllum orchids and its humidity requirements
Plumpy Bulbs Indicate Good Humidity Supply

In humid climates, as in greenhouses, it is imperative that the humid air is moving. Leaves should be dry as soon as possible, always by nightfall. Many people advise spraying your orchids with a mist of water to increase the humidity levels in the air in the direct vicinity of the orchid. This is generally not a good idea, as it is an inefficient way of increasing local humidity levels, and water will gather on the leaves and flowers. This can lead to mold spots developing on the leaves, or more commonly on the petals of the flowers. Simply put, you can use misting to raise the humidity but its not recommended for watering your orchid plants.

Fertilizer Requirements

Grammatophyllum plants should be fed consistently. The fertilizer formula should match the potting medium. We suggest using a balance type fertilizer 20-20-20 or 15-15-15. From Spring through early Fall, fertilising every seven days, with several clear watering in between. In the late Fall through Winter, a light feeding once every other week.

As with most Orchids, Grammatophyllum roots are sensitive to fertilizer salt build-up. Grammatophyllum are particularly fond of organic fertilizers, such as fish emulsion and manure teas. The organic fertilizers eliminate the concern of salt build-up in the medium, at the same time organic fertilizers decompose much, thus, one should constantly check for fungus and pests. Before fertilizing, you should water the plants soaked, about 10 minutes later, then fertilize the fertilizer, so the plant absorbs better fertilizer.

Recommended Fertilizers:

  • Balanced Fertilizer for Growth: 20-20-20 (NPK) – 2 grams per litre of water – Spray once in every alternative weeks (14 Days)

  • High-Phosphorus Fertilizer for Blooming: 0-52-34 (MPK) – 1 gram per litre of water – Spray on every alternative weeks (14 Days) - Use only on its Vegetative Phase


Grammatophyllum are one of the longest blooming orchid genera, producing flowers that last from 2 to 6 months before dropping. Normally, Grammatophyllum orchids need to have a lot of mature pseudobulbs to flowering. If the plant is too young, you should not promote its flowering by using more fertilizer phosphate, because the plant will grow slowly and can not flower. And the plant also needs time to adapt to the living environment in your home.

Pruning for Re-Bloom

grammatophyllum orchids blooming