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Using Rainwater for Plants: Benefits, Storage and Usage tips

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Rainwater is considered an alternative source of water because it doesn’t require treatment before being used. It contains no chemicals. It may contain sediment, but this is not dangerous to plants.

Rainwater when used to water plants will provide nitrogen in the form of nitrates which is used by plants to produce green leafy foliage. The pH of rainwater ranges between 6.2 – 6.8 which unlocks plant nutrients from the soil.  Rainwater can be used to water both garden and indoor plants.

As a free source of water, it can be great for your plants because of its many benefits, but it depends on how it’s collected, stored, and applied to plants.

Read on as we unveil the many benefits rainwater has on plants.  

Is Rainwater Good for Plants?

Rainwater for plants

The rainwater is better than usual water in many ways as it contains fewer chemicals, fewer minerals, and salts, almost little to no pharmaceuticals.

Kindly consider yourself a farmer or gardener if you want to know the benefits of rainwater for plants. You may have heard gardeners or farmers saying that the reason for the poor quality of crops is the lack of rain this year.

Why do they say that? Why can’t they just use tap or well water? This is where the chemistry comes in. Tap water usually possesses more chlorine as a disinfectant. Plants are quite vulnerable to chlorine.

Fluoride is also added to the tap water to remove cavities. It is said that many indoor plants fall prey to fluoride toxicity in ways like being burnt, losing their color, or having spots on their leaves.

On the other hand, Rainwater is free from all these unnecessary chemicals. Direct water from the heavens is what the plants desire.

All of those chemicals do more harm than good to the plants. Furthermore, rainwater is relatively more oxygenated than tap water. 

Plants tend to look greener and fresh after the rain. The reason is, that rainwater brings down nitrogen in the form of nitrate.

Nitrogen is considered one of the most important parts of plant growth, and rainwater brings down lots of it, which is immediately taken in by the plants. That is why plants look fresh after the rain.

The Benefits of Using Rain Water for Plants

Supplies Nitrogen for Greener Plants

Rainwater containers small amounts of dissolved nitrogen in the form of nitrates which plants can absorb.

Unlocks Nutrients in the Soil

The lower acidity of rainwater unlocks vital nutrients in the soil for plants to use.

No Chlorine

When compared to conventional water derived from taps there is no chlorine in rainwater that can pose a potential threat to plants.

Fewer Minerals

The mineral content in rainwater is little to none and will not cause any harm to plants.

Conserves Municipal Water Usage

Rainwater reduces the amount of tap water being used to water plants and vegetable gardens and therefore saves municipal water and treatment costs.


Rainwater is a free source of water which reduces the use of municipal water and the cost attached to making it drinkable (potable) for us. 

Best water for seedlings Rainwater

What Does Rainwater Contain?

Simply, rainwater is an electrolyte that is a product of various different ions like Sodium, magnesium, chloride, calcium, potassium, and bicarbonate ions.


Along with Ammonia, nitrite, nitrogen, and nitrogenous compounds. Where do these elements come from? The sources are oceans, seas, freshwater lakes, volcanoes, industries, and many more.

Many people say that they used a certain amount of tap water on the plants and the same amount of rainwater individually. The result was, as you can guess.

These components play an important role in all this. I mean, if it wasn’t for them, what different would rainwater be from others?

Carbon Dioxide

It contains carbon dioxide, which, once again, proves to be essential for plant growth. The pH of rainwater is about 5.6 to 6.8 in areas where the CO2 content is high, making it acidic. 

A study shows that plants do very well neutral and slightly acidic pH. The rainwater gets a Hell Yeah, here as well.

Communities worldwide use rainwater, instead of well water, for primary consumption, and frankly speaking, there is no harm in that.

But still, excess of anything is bad. Due to the chemicals that it contains, drinking too much of it might be bad. You are not a plant.

Properties of Rain Water

Rainwater is Slightly Acidic

Many plants require about 5.5 to 7.0 pH for healthy growth, meaning that plants are good to have a slightly acidic pH for their health.

How Low Acidity in Rain Water Affects Plants

The acidity in rainwater does not directly affect plants, however, it is the interaction of this lower acidity with the soil and its nutrient availability that is where the magic happens.

The Scientific Explanation of the interaction between Low pH and Soil –

A lower pH means there are fewer protons (positively charged ions) in the soil. Plants need these positive charges to absorb nutrients from the soil. If the soil is too acidic, the plant will not be able to take up enough nutrients.

The same goes for higher pH levels.

Rainwater has a pH of 6.5, which makes it slightly acidic and more appealing to the plants. This is one of the many reasons rainwater is better than tap water.

To test the moisture and pH of the soil you can use the cost-effective Trazon Soil 3-in-1 Meter. It not only tests for pH but also moisture content and light intensity. You can find it by clicking here!

Trazon Soil pH Meter 3-in-1 Soil Tester Moisture

Rainwater contains Nitrogen

Nitrogen is one of the three key macro-nutrients that plants need to thrive and is necessary for the development of lush foliage. Some types of nitrogen aren’t really absorbed by plants.

Rainwater can contain small amounts of dissolved nitrogen in the form of nitrates. These nitrates play a crucial role in plants.

Plants also need nitrogen to make proteins, amino acids, hormones, chlorophyll, vitamins, and enzymes. Some plants take up nitrogen through their roots while others take it up through their leaves.

Plants absorb nitrogen from the air through their roots and leaves, meaning that despite the watering method plants will still be able to absorb the nitrogen in rainwater.

The nitrogen content in the rainwater will vary in different locations.

How To Collect and Store Rainwater?

A major advantage of using rainwater is that it is free. There are minimal costs associated with installing rain barrels or cisterns. If you have a roof, you can easily install a rain barrel to capture rainwater. You can also choose to use rainwater for landscape irrigation.

The best way to collect rainwater is to collect it from rooftops or gutters rather than directly from the ground. This will ensure that the rainwater does not come into contact with any soil.

Rainwater can be stored or collected in various ways and for multiple reasons. Typically used ways are rain barrels and irrigation systems. If you want to use containers to collect and store rainwater, you might want to use them as soon as possible.

Although it is the simplest way, it is not the long-lasting one. If the skies are generous enough to send a lot of rain in your area, the use of pre-fabricated tanks might be your best bet.

You can also use gutters and pipes to collect the water and send it down to the water storage. It is called Rainwater Harvesting.

It is as simple as storing water in barrels, but it can fulfill your household demands if used wisely. Due to freshwater scarcity in many countries, rainwater harvesting has become a major system to make ends meet.

Many people do this to take control of the water supply, from the water that is simply pouring on your roof. You just have to make way for it to go through the pipes and into the water storage tank. 

This is referred to as clean rainwater and is recommended for plant irrigation.

How Long Can You Store Rainwater?

Generally, it is expected to get polluted in about 7 days. But, you can keep it clean for as long as you, by keeping it away from the insects and the light.

After losing its quality, the rainwater can even become harmful to plants. But how does it lose its quality? Once it starts to get polluted by air, light, and several other factors, its quality declines.

It is highly likely that if you keep stored water indirect exposure to the sunlight, the Algae will start to grow, as it requires sunlight for growth.

If you live in a populated area where there are a lot of cars and factories, they make the rainwater extremely polluted and unusable. This is what causes Acid rain.

Should Plants be Left in the Rain?

potted plant in the rain

Yes, you should consider putting them under rainfall after knowing its pros and cons. In contrast, tap water is said to be hard on plants due to its minerals, like chlorine. Putting your plants under the rainfall would provide them with a much-awaited bath.

Direct rainwater on your plant leaves will clear off any debris and make it easier for them to take in CO2 for photosynthesis.

Consider asking yourself if my plants need watering? Most house plants do just okay with simple daily watering. They don’t need much water at once.

Simply placing a plant out in the rain may cause it to get too much water.

An excessive amount of any type of water will cause vital nutrients to be leached out of the soil even if it’s rainwater.

Keeping it under rainfall overnight might also damage it severely.

Can Indoor Plants Be Placed in the Rain?

Indoor plants need moisture to survive. If they are not watered regularly, their leaves will dry out and die. Plants also need air circulation around them so they don’t get too hot or cold.

Placing them outdoors during rainy weather allows for both of these things.

Depending on the weather conditions you can place indoor plants in the rain. Heavier rain is not suitable while lighter drizzles will provide sufficient water for plants within a short period of time.

The weather can be unpredictable and forgetting a plant for too long in the rain can damage the soil from leaching.

It is not recommended to leave plants out in the rain during heavy rainfall.

Rain Water VS Tap Water for Plants:

As mentioned above, rainwater is softer than tap water. Most plants don’t mind tap water, but rainwater is what they desire. The reason is that it has dissolved nitrogen, it is slightly acidic, it absorbs carbon dioxide.

The lack of elements that make the tap water hard makes the rainwater more appealing. You can try it yourself. Try pouring a bucket of tap water on a plant and the same amount of rainwater on a plant.

You will see that the rainwater actually freshen up the plant, making it greener, helping in its growth, along with vegetables and fruits.

Also, rain water is more oxygenated than tap water, and you can make a pretty good guess, why is that a good trait of this water?

Overall, the rainwater scores higher in case of benefits for plants. Thank you.

How Water Plants with Rainwater

A great way to water indoor plants is by using a misting system. This method sprays water directly onto the plant’s leaves, which helps prevent evaporation and keeps the soil moist. It also provides humidity, which is important for healthy growth.

By collecting the rainwater and using efficient watering, you can supply the plant with the required amount of rainwater without running the risk of overwatering.

If you have questions about overwatered soil and how to effectively dry it our post will shed some helpful tips to quickly do so.

Misting is a good way of increasing the humidity around your plant as well as for watering lightly without the effects of overwatering. You can try this misting bottle from amazon which is cheap, durable and gets the job done.

misting can amazon

Bottom watering with rainwater is also a good method of watering because it will ensure the entire mass of soil gets watered without the risk of overwatering.

Rainwater Alternatives

Pond Water

Pond water is a good alternative to rainwater because it’s not only free but will contain a significantly greater amount of nitrates. 

What this means is that smaller amounts of water is required for plants to get more nutrients. Using pond water is similar to an aquaponic system where plants use fish waste as fertilizer in a circulating water system.

Pond water depending on its location should be tested before using it as irrigation as pollutants from nearby sources can lower the quality of the water which can potentially kill plants.

River Water

River water when compared to rainwater is also a great choice for use instead of rainwater or if rainwater collection is not possible.

The concerns with river water follow the same described above for pond water.

Spring Water

Using spring water on plants is an affordable option to provide nutrient-rich water containing minerals such as calcium and magnesium in the pH range between 7.0 and 8.0.

Springwater should first be tested to ensure that it does not contain biological or chemical contaminants that can affect the growth of plants.

The Takeaway

Rainwater is one of the best choices of water for plants. This is because it has a lower pH and mineral content. The best part is that rainwater is free and can be easily collected and stored to water plants at any time.

Rainwater is a good alternative to tap water when irrigating both indoor plant and vegetable garden plants.

We hope that we were able to answer all your questions when it comes to using rainwater on plants. We hope that you have found some useful information here.

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