Water and the Orchid - Adjustment and Measurements

Watering Orchids Optimally and Facilitating Nutrient Absorption

In the intricate world of orchid cultivation, precise water management and meticulous customization of fertilizer inputs are fundamental elements to achieve remarkable outcomes.

Orchids are exquisite and exotic plants, yet their health and flowering greatly depend on the amount of water and nutrients they receive.

In this technical guide, we delve deep into the art of mastering these two essential factors. Discover how to finely tune the water balance and nutrient levels with precision to promote robust growth and vibrant blossoms in your orchids.

By grasping the nuances of this discipline, you can establish an optimal and foundational environment for your cherished orchids, yielding results that will delight even the most discerning botany enthusiasts.

Investing in appropriate equipment to measure and adjust water is essential.

For beginners, visit the page: HTTPS://ORCHID-INFO.ORG/CONSEILS/ENGRAIS/

Water Conductivity + Fertilizing:

First, we'll utilize a conductivity meter, readily available at a Growshop or similar store. Make sure to select a device calibrated in Microsiemens, not Millisiemens, and acquire a suitable solution for device calibration.

Once your conductivity meter is ready for use, measure your water and adjust your fertilizer. The reading should be:

350 to 450 Microsiemens for most epiphytes with root watering.

150 Microsiemens for foliar watering and very fine leaves.

Fertilizer dosage varies depending on your water's conductivity. The lower the conductivity, the higher the fertilizer dose can be. There's no predefined value; a measured value is essential.

To your solution, consider adding additives like Osiryl, an absolutely revolutionary product for remarkable root development and enhanced plant growth. It's a root growth stimulant composed of lignosulfonates (Biostimulant). I recommend a dosage of 2 ml per 5 liters of water, every other watering. Add this product after adjusting the fertilizer.


40% active substance OSYR

50% dry matter

8% sulfuric anhydride (SO3)

pH: 3.7 (+/- 0.7) based on lignosulfates.

Once conductivity is adjusted, we move on to water pH.

pH Meter - Measurements and Adjustments:

To enable optimum plant absorption, it's necessary to adjust the water pH using a pH meter. Calibration is essential, just like with the previously mentioned conductivity meter.

You'll need 4 products: pH4 solution, pH7 solution, a storage solution, and a cleaning solution. Adjustments are made using two screws: the right one for calibration at pH 7 and the left one for pH 4, while immersing the electrode in the appropriate solution. Bi-monthly cleaning is recommended by soaking the electrode in the suitable solution for 24 hours.

Usage: After determining conductivity, measure and adjust the pH. Personally, I use white vinegar or organic lemon juice to lower the pH. Ideally, water pH should be between 5.5 and 5.8 for optimal mineral salt absorption, with 5.7 being optimal. Here's the equipment along with its cost:

Conductivity Tester:

I recommend the EC waterproof IP57 pen (6061) Price: 49 euros at Culture Indoor

Calibration Solution:

I use Buffer EC 2.76 MS/CM 250ml for 4.50 euros at Culture Indoor

My Reverse Osmosis System:

For continuous access to osmosis water, I've chosen a compact Dennerle 190 reverse osmosis unit, offering excellent quality at a reasonable price of 79 euros at ZOOPLUS.

I've also tested the WATSEA reverse osmosis unit and was pleasantly surprised by its great quality/price ratio, starting at 34.99 euros at ZOOMALIA.

I also have a demineralization station, but it's unnecessary if you have a small number of plants. Alternatively, you can often find free or inexpensive osmosis water at aquarium stores or nurseries. Choose according to your plant quantity.


Presented in liquid form, this miracle product is dosed at 2ml per liter. Various sellers offer it as a root stimulant. Regardless of the name, check the composition and especially the price per liter. Here's an example:

Generally, 17 to 20 euros per liter (perfect for other houseplants too!)

pH Tester:

I recommend the PH mètre Platinium waterproof IP57 from Culture Indoor for 49 euros. Unlike other devices, its electrode is interchangeable in case of deficiency.

Calibration Products:

To properly calibrate your pH tester, you'll need two solutions: one at pH 4 and another at pH 7. Calibration is done using two small screws in your tester. Be sure to read the instructions carefully. The two products are available at Culture Indoor:

4.50 euros per bottle

Cleaning and Storage Products from Culture Indoor:

7.50 euros per bottle. The first is for cleaning the probe, and the second is for storage.

At first glance, the total cost of these products may seem expensive, I admit (+/- 225 euros if you take all the products presented, excluding shipping). However, consider it essential to maintain plants over time, control your water, and achieve exceptional blooms

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