Is Rainwater Good for Plants - What are the Pros & Cons?

Should you put your indoor plants outside to receive water if it is raining? It turns out that there are some great benefits to using rainwater (soft water) for houseplants. Rainwater tends to have fewer chemicals than what you find in tap water, is cheaper than buying bottled water to water plants, and conserves municipal water usage.

So, what is in rainwater, and what is the pH range for it? What nutrients do plants need to survive? How does rainwater compare to tap water and other types of liquid? Are there any downsides to putting plants outside when it is raining?

Here is the complete breakdown of why rainwater is primarily suitable for plants.

Table of Contents

What Does Rainwater Contain / What is the pH Level Range?

According to Bite-Sized Gardening, there is a load of micronutrients that one can find in rainwater. Rainwater contains water, phosphorus, nitrogen, calcium, potassium, magnesium, sodium, and nitrates. According to Stormwaterx.com, rainwater tends to have a pH level of around 5.6. Stormwater has a pH level range between 6.5 and 7.2

What Nutrients Promote Plant Growth?

Plants need nitrogen, phosphorus, potassium, and calcium to grow healthy and strong. In addition, plants need adequate soil, the right temperature environment, and the appropriate amount of sunlight.

Why is Rainwater Good for Plants?

There are many advantages of using a rainwater collection on your plants to give them water. Here are some of the key reasons to use rainwater on your houseplants.

It has a Load of Healthy Organic Matter and Nutrients

Rainwater contains nitrates, an essential element that plants need to grow healthy and strong. In addition to that, rainwater also has phosphorus, collects carbon dioxide from the sky, sodium, magnesium, potassium, and calcium. Not only does rainwater have these critical nutrients, but it doesn’t have the chemicals that hard water has, like fluoride toxicity or alkaline, where too much of that can cause plant growth issues.

Is Cheaper than Using Tap Water

While most of us don’t think tap water costs money, it does via a monthly utility bill. Your water bill comes from using the shower, running the dishwasher, cleaning clothes in the washer, and finally, using the sink. If you are looking for a more budget-friendly way to give your plants water, put them outside to collect the rain droppings.

Can Collect in a Rain Barrel for Future Use

Rainwater harvesting is generally a DIY water system that people have at their homes to collect rainwater. Collecting rainwater from a storm is an excellent way to treat your plants with that type of water later. Instead of letting that water runoff to a storm drain, collect it for further use with a bucket!

Helps Make the Soil Loose

A light and steady amount of rainfall can help loosen up the soil for plants. The consistent rain hitting the dirt can break up hard soil, opening the ground to more oxygen flow and for the roots to have space to move. Roots that expand naturally in the soil play a critical role in photosynthesis, so while green leaves will appear to signal that the plant is doing fine, the ground and the roots are just as important and might need the soil to be loose to work correctly.

A Green Way

Collecting runoff water from a rainstorm helps eliminate excess water usually going down the drain. Since some drains ultimately dump their sewage into lakes and rivers, you are doing your part by reducing some of that excess dirty water that would eventually end up in a river or lake.

When is Rainwater Not Good for Plants?

While there are plenty of benefits to putting houseplants outside to collect rainwater, some things are to known. Here are some things to be cautious about when using rainwater on plants.

Acidic Rain / Pollutants in the Water

Consider testing the rainwater to ensure it does not have acid or other pollutants, depending on where you live. For example, if you live in an area with lots of air pollution, then using rainwater on plants might require some boiling first to remove any harmful pollutants before giving them to plants. When in doubt, consider collecting the water during a rainstorm and test the liquid to see how safe it is and if it would work well for your plants.

Heavy Rain

While a nice and consistent drizzle of rain can work well for plants, heavy rain can cause severe damage to your plants. If the rain starts coming down hard on plants, the structure can suffer under that pressure. When putting your plants outside to collect the rain from the sky, be mindful that your potted plants are not used to heavy rain, and thus heavy watering can cause damage to them.

Not all Plants Want Much Rain / Water

Not all plants want as much water as others. While putting all of your houseplants outside to receive rainwater might be tempting, it is worth noting that not all plants need the same amount of water. For example, if you put a cactus outside during a rainstorm, you risk overwatering it, which can then run into other issues for the plant.

Conclusion: Is Rainwater Good for Plants?

In summary, rainwater for plants, in general, is a great idea. Some of the reasons it is an excellent idea include it being free, a green way to give plants water, has loads of nutrients, and can loosen up the soil with its force. Not only is rainwater great for plants, but you can also collect that water for a later time, which means you can give your plants rainwater even if it is not raining.

The main reason why rainwater is not a great idea for plants is if you live in an area with poor air quality. Acidic rain and pollutants might be prevalent in the area you live in, so make sure you test the rainwater to ensure it will be safe for plants. Outside of that, the heavy rain and or wind might cause structural issues for plants, so keep an eye on them when you leave them outside to collect rainwater.