This section is from the book "The Florists' Manual", by William Scott. Also available from Amazon: The Florist's Manual.
This same old advice must be given with emphasis about drainage. A crock and piece of green moss are enough for plants in a 5-inch or 6-inch pot, but when in larger, and more especially when in very large pots or tubs and boxes, which they may remain in for four or five years, they should have two or three inches of drainage. If water passes quickly through the soil, whether the plant is in a 4-inch or 14-inch, then the drainage is all right. If it does not, and it is slow in disappearing from the surface, then it is all wrong. In spring and summer, when making leaves fast, they want copious watering, but usually when thoroughly watered, once a day is enough. In winter, with a lower temperature, darker days and slower growth, less water is needed. A gardener knows at a glance whether they are dry or not. Palms in winter want as regular watering as in summer, but with the difference that after a watering they may remain moist for two days, while in summer, with the pots full of roots, they want a watering twice a day.
Syringing is most essential to all palms. First it creates that moisture in the atmosphere so congenial to their growth, and then again it cleans their foliage of insects, more especially that nuisance, the mealy bug. If the house is paved with stone or cement, you should syringe at least twice a day in summer, and frequently throw water about the paths and benches. If the floor is gravel or earth, there is always more or less moisture rising, but syringe every day, and when you do syringe, don't hold and direct the hose as if you were watering a bed of radishes, but direct your fine but strong stream upwards at the underside of the leaf. Constant syringing on such palms as latanias, kentias and arecas is another reason why the soil should be in good condition to let the water pass through. In winter syringe occasionally in the morning, and when firing hard damp down the houses; less moisture is needed in winter, as the plants are in less active growth.