Is Deionized Water Good for Orchids?
Short answer
Yes, as long as you also fertilize. Orchids are sensitive to salts and minerals that build up in their potting mix, and deionized water adds none. But deionized water also contains no nutrients, so feed your orchids with a balanced orchid fertilizer and flush the pot now and then. Carnivorous plants such as Venus flytraps need low-mineral water even more.
Why orchids react to minerals
Most popular orchids, such as Phalaenopsis, grow on trees in the wild, where rain water is very low in minerals. In a pot, minerals from hard tap water and leftover fertilizer salts accumulate in the bark or moss. The American Orchid Society describes how excess salts can burn root tips and leaf tips (AOS: salt toxicity). Low-mineral water slows that buildup.
How to water orchids with deionized water
- Water thoroughly when the mix is nearly dry, letting water run out the drainage holes.
- Feed regularly. Use a balanced orchid fertilizer at the label rate. The AOS fertilizer guide covers feeding and recommends low-mineral water, such as rain water, if your tap water is too hard (AOS: fertilizer).
- Flush now and then with plain deionized water to rinse out leftover fertilizer salts.
- Use room-temperature water and avoid leaving water in the crown of the plant.
Carnivorous plants: low-mineral water is essential
Venus flytraps, sundews, pitcher plants and butterworts grow in nutrient-poor bogs. The International Carnivorous Plant Society says tap water is only suitable if its total dissolved solids (TDS) are below about 90 ppm; above that, it recommends low-mineral water such as reverse osmosis or clean rain water (ICPS). Deionized water is another low-mineral option. Unlike orchids, most carnivorous plants should not be fertilized through the soil.
| Plant | Low-mineral water? | Fertilizer |
|---|---|---|
| Orchids (Phalaenopsis, Cattleya, Dendrobium) | Helpful | Yes, balanced orchid fertilizer |
| Venus flytrap, sundews, pitcher plants | Essential | No soil fertilizer |
| Bonsai and terrarium plants | Helpful in hard-water areas | Yes, per species |
| Most houseplants | Optional | Yes |
Which Renew Labs water to use
Signs your orchid needs a flush
White crust on the pot rim or the surface of the bark, brown root tips and leaf tips that dry out are common signs of salt buildup. Water the pot thoroughly with plain deionized water two or three times in a row, letting it drain completely each time, to rinse leftover fertilizer salts out of the mix. Repot into fresh bark when the old mix breaks down.
Renew Labs Plant & Orchid Water, 1 gallon is deionized and ready to pour, and the 2-pack lowers the price per gallon. Keeping a terrarium or paludarium? Aquarium Top-Off Water replaces evaporation without raising hardness. Read our full guide to deionized water for plants and orchids.
Related questions
Do I need to fertilize if I use deionized water?
For orchids and most houseplants, yes. Deionized water has no nutrients, so feed with a balanced fertilizer (AOS). Carnivorous plants are the exception and should not get soil fertilizer.
Can I use tap water for my Venus flytrap?
Only if it is very low in minerals. The ICPS says tap water should be below about 90 ppm TDS; otherwise use low-mineral water (ICPS). A cheap TDS meter tells you.
Is rain water better than deionized water for orchids?
Both are low in minerals. Rain water is free but varies with your roof and gutters; deionized water is consistent every time.
Why are my orchid’s leaf tips turning brown?
Brown tips can have several causes, including salt buildup from fertilizer or hard water. Flushing the pot with low-mineral water and feeding at the label rate can help.
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Keep reading
- What Is a Beyond-Use Date (BUD)?
- Can You Use Tap Water in an Ultrasonic Diffuser?
- What Is ICP-MS Testing?
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