Water Quality & Orchids

Orchids need water to drink and for humidity. Orchids absorb nutrients from water. Understanding water quality and making some adjustments in the water quality parameters could make the orchids grow and bloom better. Water quality is determined broadly by mineral content, salinity & pH.      

What parameters are important

Total Dissolved Solids (TDS) in Water – This is sum of all mineral constituents that are soluble in water. There are a wide variety of substances of dissolved solids like sodium, chloride, sulfates, calcium, bicarbonate, nitrates, phosphates, iron, and magnesium
Higher the TDS value of the water more would be the quantity of dissolved solids in water and would be harsher on the orchids. Lower the TDS on the water, fertilizer would provide more punch and be effective.
If the water has higher TDS measurement, reduce the amount of fertilizer to be added, as it would burn the roots and foliage. Smaller plants would be impacted more with water with higher TDS.

TDS level could be measured using an EC (Electrical Conductivity). TDS meters (HM Digital) are available in market for around Rs.600 and convert the EC to PPM (Parts Per Million).

PPM Value	Favorability
<60 PPM	Perfect Condition to grow orchids	Paphs, Phrags & Pleurothallids do not grow well if TDS is >60
60-120 PPM	Suitable	Majority of the genus do well
120-200 PPM	Moderate	Majority of the genus do well
200-500 PPM	Limited choice & possibly not best growing specimen	Dendrobium hybrids & Phal hybrids do ok but not at their best potential
>500 PPM	Not Suitable to grow orchids

pH of Water

pH is a measure of alkalinity or acidity of water. pH of water affects the availability of  of minerals. Higher the water pH (alkaline), certain minerals would not be available to the plant. Once the fertilizers are added to the water, pH of around 5.5-6.5 (mild acidic) is very good for growing orchids.

If the pH of the fertilizer is very high are low, we should adjust the pH to 6.5 to maximize of the effect of dissolved minerals absorption

There are combined TDS+ pH meters available for around Rs.1000 to measure the TDS & pH of the water. I use a soil pH meter that I bought long ago but seem to be working

Other Practices to avoid

1)    Using Water softeners would worsen the situation by increasing sodium or potassium chloride in the water and is harmful for orchids

2)    Boling water would not remove the minerals but increase the concentration of minerals in the water (H2O would evaporate leaving more mineral residue)

3)    Using chlorinated water directly would be harmful. If the supply water were only chlorinated then leaving the water in an open vessel for 24 hours would usually be sufficient for chlorine to evaporate.

4)    Using chloramine water would be harmful. Unlike chlorine treated water, no easy process can remove chloramine from the water.

My Water Source TDS readings

Source	TDS
Rain Water	25-40 PPM
Bore well	350-400 PPM
Tanker Supply	350-400 PPM
City Water (BWSSB) Supply	120 PPM

I have started collecting rainwater from my terrace in a barrel and use it for my daily use and orchids love it.

Pure water or rainwater could have lower levels of calcium and magnesium and could impact the health of orchid and hence it is important to use fertilizer with micronutrients. Calcium is responsible for strong and healthy cell wall and calcium deficiency would weaken the cell walls and make them susceptible to fungal and bacterial infections.

It is recommended to use high TDS water once in 3-4 watering’s to compensate for calcium deficiency or use a magnesium/calcium supplement with rainwater in the fertilizing regimen or use a fertilizer that has micronutrients

Solutions for Bad water quality

1)    Easiest solution would be collect rainwater in barrels and store and use them for watering orchids. This is what I do at my home.

2)    If the number of orchids in your collection is low then possibly look at using distilled water.

3)    If the number are an orchid in your collection is more then possibly look at using a reverse osmosis (R.O) setup. If you have a R.O setup for your drinking water, you could use the same water

4)    If we use only rainwater, then we would have to supplement calcium to the plants in some form alternatively, we could use regular tap water once in 4 watering to supplement calcium.