Orchids have a bit of a reputation for being tricky to care for, but in my experience, most of the time, successful orchid care comes down to watering with not too much and not too little. After several years of growing Phalaenopsis (my favourite orchid and the most commonly sold orchid type), I have run a few informal experiments of my own, and what I discovered was that most of the popular “rules” for watering orchids are oversimplified or just not correct. In this article, I set out what actually works, backed by the tests I did myself.
1. Debunking the Ice Cube Myth
This one needs addressing because I see it repeated online on blogs and SOIcial media. How the idea that “watering orchids by using 3 ice cubes a week” took off baffles me! Whilst you could argue it prevents overwatering, it presents a different problem for your TROPICAL orchid (hint, hint).
I decided to test this myself with a mini experiment where I used two Phalaenopsis orchids side-by-side in the same room to control the variables. For 8 weeks, orchid A had 3 ice cubes once a week, while Orchid B had a thorough soaking with room temperature water for 10 minutes when the pot felt dry.
By week 4, Orchid A’s top roots (the ones which the ice cubes directly were in contact with while they melted) had turned mushy and black, and the bottom half of the pot felt dry since the volume of water in three ice cubes wasn’t enough to ensure the potting soil was evenly moist (and the roots all had access to moisture). It just got absorbed into the top layer and then dried out without reaching the roots. Orchid B, meanwhile, had plump, lovely green roots throughout the entire pot and even started to grow a new leaf.
What I learned…
- Cellular thermal shock of the roots. Phalaenopsis orchids are tropical epiphytes (they actually grow on trees rather than rooted to the ground), and their natural temperature range is between 18 and 29°C (65–85°F) an placing cubes of ice directly on or even near the roots causes cell lysis where the outer cell walls of the root tissue freeze and collapse. This damaged tissue makes the orchid vulnerable to rot.
- Severe underwatering. The three standard ice cuble ads up to around 3 tablespoons or 45 mL of water, which is not enough. The bark or moss absorbs all the moisture at the tip, and then it evaporates, which leaves about 70% of the root zone in drought.
So the ice essentially freeze-burns the roots at the surface and leaves the rest thirsty. While it does prevent overwatering, you get two other problems in its place!
2. What Actually Works: Two Field Tests
Rather than a fixed pattern of how often you should water orchids, it’s better to understand how each orchid potting mix and roots interact. Here are two experiments I did for watering orchids to show what I mean.
Experiment A: Pouring vs. Soaking
Bark-based orchid potting mix is what I actually prefer; however, it can become naturally hydrophobic (repels water), so water can actually run around it and then out the pot rather than absorb into the bark so that the roots can access it.
To see this for myself, I weighed a completely dry 12 cm (10 inch) potted orchid before and after watering two differing ways. First I poured 500 ml (about a pint) at the base of the plant, and about 420 ml ran through the substrate and out the drainge hole in the base without actually absorbing properly. Only around 80 grams (which is the same as 80 ml) absorbed, so the bark was mostly dry.
Then I let the same pot dry out again, and this time I placed it in a basin of lukewarm water for 20 minutes so the bark could draw up water through the drainge hole and hydrate properly. This time with this method, the pot was 210 grams heavier, which meant nearly 3 times the water had actually absorbed.
This method of bottom soaking gave the bark and the spongy root covering (called velamen) enough time to absorb the water without letting it just pass through.
Takeaway: If your pine bark around your orchid’s roots has dried out completely, then watering from a tap or container is going to be enough and soaking your orchid in a basin of water for 2 minutes (and then letting all the excess water drain away) is the most effective way of watering.
Experiment B: Reading the Velamen Instead of the Calendar
The other habit I have changed is watering on a fixed schedule, and instead I do what I call a velamen check.
As I alluded to, velamen is the spongy, silvery-grey outer layer of the roots, and when it’s dry, the air-filled cells inside reflect the light, which is why it looks silver/gray. The instant the water reaches these cells, they fill up, and the colour changes to a brighter green chlorophyll layer underneath, which is visible because the velamen is now translucent.
I stopped watering according to a calendar years ago due to this. If the roots are silvery grey, then I give my orchid a soak (or place it in the basin), whereas if they are still a shade of green, then I leave the orchid alone completely, even if it’s been 2 weeks since I last watered (which can happen in the winter when the orchid’s demand for water reduces). The reason for this is that roots dry at different rates depending on pot size, humidity, airflow and time of year, so a fixed every 7 days rule is going to cause you to overwater some orchids and underwater others.
3. Putting It Together: A Simple Watering Routine
Based on all of these experiments, here is the routine I actually follow…
- I check the roots and not the calendar! Look at the velamen colour through the side of a clear pot or lift the pot to judge the weight (which is the technique I use), and if the pot is dry it should feel very light, and you’ll know straight away.
- Soak the potting mix rather than a light watering. When the roots are silvery, I submerge the pot in room temperature water for 10 to 15 minutes and then let it drain completely before I put it back into its decorative pot.
- Do not use ice! This can cause root rot and hurt your orchid.
- Always let the pot drain fully. You do not want standing water around the roots of your orchid, as this too results in root rot, so always let excess water drain away, which means watch your outer pots and trays do not fill up with water.
Orchids are not as delicate as their reputation suggests; it’s just about getting the balance right, and once you start reading the orchid’s roots instead of following a formula, your orchid can thrive.
Do you have any questions about watering your orchids? Please leave a comment, and I’ll respond, and we’ll sort it!