It is nice to see some new orchids coming to the local plant dealers. This is the first Grammatophyllum I’ve had or seen. Outside this plant wants light shade, which indoors means a bright, sunny window.
Temperatures can be as hot as 105’F These grow outside in Houston but it’d really be much happier if you kept the temperature under 85’F. Nights should be around 55’F So find a drafty window or door to put it near. Or place it outside in light shade when not in bloom. It can tolerate an occasional light frost.
Watering should be frequent, water frequently but do not let it sit in water.
Grammatophyllums are from the rainforests of Asia, so keep the humidity as high as you can.
As you can see in the photo these are large orchid plants, so they are great for floor plants.
Watch for rust, give it more sun if you see the rust fungus on the plant and better air circulation.
The more sun it gets the more blooms you will get.
Fertilize regularly, most orchid growers are now using the time release pellets when they repot their orchids. I still prefer my liquid fertilizers.