What are critical water quality factors?
Written by
Kiana Okafor
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.The quality of water determines whether the orchids can utilize the nutrients from the fertilizer appropriately. I learned this lesson the hard way when my orchid's feeding stopped working after months of perfect 8-12 day feeding schedules. Eventually, I learned to check four factors that significantly improved my results. The pH levels of your water significantly affect the solubility of nutrients. TDS readings of your water indicate how much mineral content is present in the water. Temperature is important to correct root function. Finally, purity is important to avoid chemical exposure to the orchids.
pH Balance
- Optimal range: 5.5-6.3 for nutrient solubility
- Test weekly with strips or digital meters
- Adjust using citric acid (lower) or baking soda (raise)
- Affects nitrogen and iron availability significantly
TDS Levels
- Keep below 100 ppm to prevent mineral lockout
- Measure with handheld TDS meters before each watering
- High levels indicate excessive dissolved salts
- Causes root tip burn and stunted growth over time
Temperature & Purity
- Ideal temperature: 65-75°F (18-24°C)
- Eliminate chlorine and heavy metals completely
- Use activated carbon filters for purification
- Cold water shocks roots reducing absorption capacity
pH testing is simple to manage. I prefer to use digital pH meters, which are fairly inexpensive (usually under $20). Simply submerge the probe into the water sample to read its pH level. You can use food-grade citric acid to decrease a high pH and potassium bicarbonate to raise a low pH. My experience has shown that pH values vary from week to week, so I like to test once a week for familiarization and to gain knowledge of the changing values, particularly with stored rainwater.
To manage your TDS effectively, you must monitor it regularly. My TDS meter remains with my watering can, and when the readings are above 100 ppm, action needs to be taken. If it is tap water, consider installing an in-line reverse osmosis system. If it is stored water, think about distillation. High TDS will appear as a white crust on the pots and the surface of the media.
Temperature and purity are the final components to complete the picture. Always ensure that your cold water is warmed to room temperature, measured at 70°F (21 °C). Chlorinated water should be boiled or aerated for 24 hours to remove the chlorine. Heavy metals can be removed using specialized filters. I keep a dedicated watering can inside my home, so I don't need to worry about the temperature; it is always maintained at a consistent 70°F throughout the year.
With proper water, you will see immediate improvement in all aspects of your orchids. New roots will show up white and fuzzy. Leaves will develop a consistent green color. Flower spikes will create a more robust structure. I observed flowers multiplying by a factor of two in only six months after optimizing these four parameters. Water quality clearly makes the difference between success and failure in a fertilization plan.
Read the full article: How to Fertilize Orchids: Ultimate Guide
