Orchids should always be watered in the morning, so they can dry by the evening.
The frequency of watering depends on the season and the temperature. A rule of thumb is to water orchids once a week in winter and twice a week when the weather is hot and dry during summer.
The size of the pot also helps determine how often an orchid needs water. For example, an orchid in a 15 cm diameter pot should be watered about every 7 days, while one in a 10 cm diameter pot should be watered once every 5-6 days.
It is important to know that even if the surface of it is dry, the soil around the roots can still be wet. Press your finger or a pencil into the ground about 1 inch deep, and if you find that the soil is still wet, do not water yet.
The quality of the water is also extremely important. Because tap water is treated with chemicals, usually chlorine, it needs to be used with caution. For orchids, rainwater is without a doubt the best choice. Rainwater absorbs many organic substances, such as soil particles and pollen, and thus nourishes plants better.
The temperature of the water is also important. It is best if the water temperature and air temperature are roughly the same, but healthy plants can withstand smaller temperature differences as well.