Updated: Feb 5, 2022
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.
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
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.
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.
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"
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.
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.
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.
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.
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 rebloom on old spikes with a new stalk emerging from a triangular node along the stalk. To trigger re-blooming, your orchid will need a little more attention than what you usually give it. The thrill when your orchid blooms for a second time, however, makes the small investment in time and effort required to trigger orchid reblooming well worth the effort.
Steps to Trigger Re-blooming:
Reduce irrigation for about two weeks to create a dry period for the plant. If you regularly irrigate the plants once a day, then now take, 1-2 days to water once. Only irrigate the roots, do not irrigate the leaves.
Then fertilize 0-52-34 (MPK) to stimulate flowering for 3-4 consecutive weeks.
After a drought, the plant will absorb the fertilizer very well. Pseudobulbs will quickly get old enough to accumulate energy to prepare flowers. Continue to reduce irrigation for about 2 weeks.
After this fertilizer application, if you don't see any spikes coming, start watering as usual and prepare the plant for next vegetative phase.
Potting, Media and Propagation
There are two main reasons why a Grammatophyllum orchid may need re-potted. The first is when the growing media starts to break down and decompose. The second is when the roots outgrow the pot the orchid is growing in. Grammatophyllum do not resent being disturbed, so repotting should be undertaken whenever necessary. The best time is, after all, flowering has ceased, and new growth is just beginning. To minimize root damage, warm water soaks for 10 minutes, which will make most very pliable and easier to remove from the container. When dividing Grammatophyllum plants, always divide into parts with at least four pseudobulbs. Remove any dead roots from the divisions, then lay the divisions aside until new root growth begins. When planted in small pots, the plants will produce better flowers, and the roots of the plant tend to grow opposite to the gravity dimension and will spread out into a sphere. After that, dry out, reduce irrigation for the first 7-10 days to help the plant heal wounds.
"Newly Re-potted plants should be placed in slightly lower light for few weeks"
Orchids generally prefer to be root constrained, so don’t change to a larger pot than necessary. The roots of orchids contribute to photosynthesis and energy generation, so giving the roots access to light enables them to contribute to the overall health and strength of the plant. As the roots gain a lot of moisture and nutrients directly from the air, having plenty of ventilation and drainage holes will enable good air circulation to the roots of your orchid.
The most common growing media to use is a tree bark-based mix, although any fast-draining medium such as Coconut husk chips could be a viable alternative. The plant will thrive much better with a smaller volume of healthy roots, than a larger volume of roots with a diseased or unhealthy section.
Pests and Other Grammatophyllum Related Problems