It depends. Not my favorite answer to any question — but hang in here with me for just a bit. (Your houseplants will thank you for your diligence!) Houseplant water is an important topic for plant lovers, and getting it right can help your plants thrive. In some cases — if the water you’re using is really problematic or your plant is very sensitive — it can be a matter of plant survival.
To help you decide the best choice for you, here are the likely options for houseplant water and the pros and cons of each.
Tap water
Most tap water is okay for most plants. But there are some caveats.
- If your tap water is softened, don’t use it on your houseplants. No gray area here — tap water that’s been softened contains too much sodium, which is terrible for your plants!
- If your tap water contains high amounts of chlorine and/or fluoride (chemicals used to purify and fortify the water), some plants will rebel. (Air plants, spider plants, orchids, and cacti don’t love tap water.) You can easily find out what’s in your unfiltered tap water by plugging your zip code into the Environmental Working Group’s Tap Water Database. (This is a great way to determine if you want to drink your tap water, too!)
- If your tap water is hard, it might contain large amounts of minerals, such as calcium and magnesium, as well as bicarbonates and sulfites, that can build up in the soil. (You can sometimes see the accumulation on top of the soil, in the soil, or on the sides of your pot.) This isn’t ideal either. While these ingredients are harmless for a while, they can eventually buildup in the soil and affect its pH, which can harm your plant. Chemical and mineral buildup happens more quickly in small pots with little soil.
If you use hard water, occasionally flush out the soil in your houseplants by watering them well with rainwater, distilled water, or filtered water.
What about leaving tap water out overnight before watering my plants?
Some people suggest leaving tap water out for 24 hours to allow the chemicals to evaporate. And some of the problematic chlorine does evaporate. But other chemicals (such as chloramine) don’t. In fact, because some of the water evaporates too, the remaining chemicals become more concentrated, not less. Still, if chlorine is your problem, this might be a workable solution.
Filtered tap water (a filtration system that doesn’t use salt, such as an in-home filtering system or a pitcher filter) might be your best bet. Filtering cleans your water of large numbers of chemicals and bacteria without the use of salt. Heads up, though: If you use water that’s been filtered of minerals, you’ll want to be diligent about fertilizing your plants, because your water won’t be providing all the minerals they need.
Tip: After dinners at our house, I empty remaining drinking water (which is filtered) out of glasses into my watering pitcher. Then I use that water for houseplants. We don’t waste water, and the plants appreciate the quality drink! (If the water is cold be sure to let it come to room temperature before using it on plants.)
Distilled water
The big pro of distilled water is that potentially harmful impurities (chemicals, minerals) have been removed. It’s soft water, but it doesn’t contain the salt used by water softeners. It has a neutral pH level.
Distilled water will safely give your houseplants a lovely drink of pure hydration. Cons are that your plant won’t receive any beneficial minerals, either. So you’ll need to be sure you provide fertilizer occasionally to make sure your plants get the nutrients necessary to help them grow. Another con is that you’ll need to buy distilled water — which adds both to the cost of watering your plants and environmental waste (if you’re buying plastic jugs of it). You can distill your own water, but it’s a cumbersome project.
Rainwater
Rainwater is ideal for plants. It has the right minerals for your plants as well as high oxygen levels, which is great for your plant’s roots. (It can help the roots grow faster and take in nutrients faster, which means they’ll grow more quickly and strongly.)
If you have a garden or just a lot of houseplants, you might want to install a rain barrel. (I’ve had a couple and love them!)
But even rainwater has a caution. If you live in an area with environmental pollution (from manufacturing, for example), the rainwater might be too acidic for your houseplants.
Spring water
If you have access to pure spring water, lucky you (and your plants)! Spring water has natural minerals that are good for your plants. Of course, buying bottled spring water for your houseplants isn’t a sustainable option. If you’re drinking spring water and have enough left over for your sensitive orchid, though — go ahead and give her a drink. She’ll love it!
A few watering tips
- Use room temperature water, not cold and not warm.
- Water more in the hot weather, a bit less in the winter.
- Water early in the day, not at night. Don’t let your plants go to bed wet. (Water will evaporate better during the day, which means the leaves won’t stay wet overnight.)
- Fully water your plants — so that the water reaches the roots in the bottom of the pot and drains out. Don’t water your plants gingerly (a drop here and a dribble there). Give them a good drink once in a while (weekly is good for many plants) and then let them dry a bit before their next drink. To make sure the roots are getting a drink, water your plants until the water runs out the bottom of the pot. Empty any water in the saucer underneath when you’re finished, though. (I take all of my smallish plants to the sink and water them there every weekend.)
- Don’t overwater. The worst thing you can do to most plants is overwater them. Roots need oxygen; they need to dry out between waterings. For most plants, you’ll want to let the top inch or so dry out between waterings. Dip your finger in about an inch (to the first knuckle after the fingernail). If the soil feels dry, give your plant a drink. BTW, that first knuckle is called the distal phalanx or DIP for short. So this is the DIP test!
Signs that you’re overwatering:
- Yellowing leaves that are dropping
- Wilting leaves (of course this is also a sign of a thirsty plant, so check the soil!)
- No new growth or very slow growth
- Brown, saggy young leaves
- Gnats flying around the plant (these like fungus, and they’re attracted to wet soil)
- Algae on the top of the soil
If you’ve really overdone the watering, you may need to repot your plant in fresh, dry soil. But usually you can just let the soil dry out for a bit and start fresh.
What kind of water do you use for your houseplants? Please share your watering tips with the C2K community!
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