Watering houseplants is always a bit complicated, even more so with orchids, whose thick leaves don’t react much to changes in soil humidity. It’s hard to tell if they’re soaking wet or bone dry, yet they like neither situation. Instead, the ideal situation for most indoor orchids is when you replicate the effect of rainfall, that is, soaking the roots, then letting them dry out almost completely before watering them again.
If they soak too long in a soggy substrate (growing mix), the roots will start to rot and soon the orchid will die. They’ll do better if they are regularly stressed by a lack of water, but still, they won’t be as attractive nor bloom as heavily as they should. So, the rule is: wait until the substrate is almost dry before watering again. But how do you know when the substrate is “almost dry?”
A Strict Watering Schedule?
First, the “water once a week” method, which so many gardeners try to put into practice, is unreliable.
Okay, sometimes you hit the right rhythm by accident and thus it may work for a while, but if the plant grows it will “drink” more water and be more quickly in a state of water distress. Or, in winter or after a week of gray weather, when the light is weak, the plant will not have used all its water after a week. If the air in your home is very dry, you need water more often; if it’s humid, less often. Bark-based substrates require more frequent watering than sphagnum-based ones. And the list of factors influencing watering needs goes on and on.
So, no, you can’t put an orchid on a strict watering regime and expect everything to go well. You have to be more flexible than that.
The Finger Knows
The classic method for determining orchid watering needs is simply to push a finger into the substrate. If it feels dry to the touch, water. If it feels moist, repeat the test a few days later. If you are not sure, that’s likely because the substrate is close to being “almost dry.” In that case, wait yet one more day before watering.
This method is truly effective: generations of orchid lovers have applied it with great success.
If you don’t like getting your finger dirty, you can try inserting a pencil or wooden coffee stick into the substrate. If the wood changes color (darkens) because it has picked up moisture, the substrate is still humid. So, don’t water. If the wood does not change color, the substrate is pretty dry. Do water.
Or use a moisture meter, readily available in garden centers and even hardware stores. Push its probe (metal rod) into the substrate and check the results on the dial. When the needle moves into “dry,” it’s time to water. It’s important to thoroughly clean the probe after each use; otherwise it will start to give false results fairly quickly and you don’t want that!
Give Them a Lift!
Or weigh the orchid. Not on a scale, but just by lifting the pot. It will weigh much less when it is dry than wet. When you first try this, use another method concurrently to confirm your results, but eventually, you’ll discover that you’ll develop a sort of “weight memory” and this method may well become your method of choice for determining when an orchid needs water.
Doing the Deed
So, it finally is time to water. What should you do?
The water should be lukewarm or at room temperature. No, don’t water with ice cubes, a method that stresses the plant out to the highest degree. (Read Should You Really Water Orchids with Ice Cubes to understand why that isn’t a good idea.)
And yes, you can use water directly from the tap: there is no need to let it “sit” overnight, despite a popular horticultural myth. However, avoid softened water, far too rich in salts … and also distilled water, which contain no salts at all.
Rainwater is even better for orchids than tap water, but the difference is so minimal in orchids it’s not worth bending over backwards to apply it. Instead, keep your rainwater for the plants that are really need it, such as carnivorous plants.
Moist Roots, Dry Leaves
Try not to moisten the foliage when you water, as this can lead to disease, especially if the leaves remain moist overnight. If you accidentally spill water on the leaves, gently wipe the excess up with a cloth.
And if you’re a naturally messy waterer, getting water everywhere, why not water your orchids in the morning? That way, any water spilled on the foliage or working its way into spaces between the leaves will have time to evaporate before night comes.
From the Top, From the Bottom or by Soaking?
Orchids can be watered from above, by gently pouring water over their substrate until you see excess water flowing out of the pot, or from below, pouring the water into their saucer and then allowing the substrate to soak in water for a short period of time. The two methods give similar results. In both cases, simply empty any excess water about 10 to 20 minutes after you water. However…
Nowadays, few orchids are placed in plant saucers. Instead, they are almost always sold double potted, that is with a cachepot (without a drainage hole) on the outside and a grow pot with drainage holes, often transparent, on the inside. But typically the grow pot fits very tightly in the cachepot and the result is that you really can’t tell if you’ve watered too much, correctly or not enough.
That being the case, the easiest way is to water an orchid in a cachepot is by soaking it. Leave the plant in its cachepot and water abundantly until the water rises to the edge of the grow pot. Next, let it soak. Then, after 10 to 15 minutes (never more than one hour), remove the grow pot from the cachepot and let it drain thoroughly, then empty any surplus water that accumulated in the cachepot too.
Rather than bringing my orchids to the sink to empty the pots, I always place a plastic bucket in my plant room where I can pour the drainage water.
Finally, replace the grow pot back in the cachepot and it’s done.
Soaking is actually the best way of watering an orchid, as you can be sure all the roots will get their fair share of moisture, yet any surplus will quickly drain away. It’s important, however, not to let the plant soak in water for much more than an hour. That could lead to rot.
There you go! Watering an orchid is not so difficult when you know how to do it right!