Why and How to Collect Rainwater for Houseplants


When it comes to healthy plants, nothing beats the effects of rainwater. Keep your indoor potted varieties looking their best with regular doses of rainwater. Here’s how to get started.


Nothing beats what nature can provide in terms of growing healthy plants. Even houseplants will benefit from exposure to natural sunshine and humidity. But, if you want to make a real difference for your plants, it’s time to treat them with spring rainwater.

Here, we’ll look at the benefits of rainwater for plants and the ways you can harvest some most efficiently.

Why and How to Collect Rainwater for Houseplants
6 Benefits of Rainwater

While you might assume that filtered tap water offers the purest form of hydration, it turns out rainwater has the advantage. Below are six known benefits of using it on plants.

1. Less Chemical Toxicity

Tap water may seem pure, but most contains a cocktail of chemicals that is less than ideal for houseplants. For example, your water likely includes chlorine as a disinfectant and fluoride to help prevent cavities. Unfortunately for houseplants, these elements won’t offer them any benefits.

Most are susceptible to chlorine toxicity, which can result in burnt leaf margins. Others, including dracaenas and spider plants, are sensitive to fluoride toxicity and experience symptoms like burnt, discolored, and spotted leaves. Your tap water may also contain water softeners or a high concentration of sodium, which further stresses houseplants.

Why and How to Collect Rainwater for Houseplants

Rainwater doesn’t contain these compounds, meaning that it’s less likely to stress your plants over time.

2. Higher Oxygen Content

Ounce for ounce, rainwater contains more oxygen than tap water. That’s a benefit for houseplants, as it improves the respiration process and enhances nutrient absorption. The long-term result is healthier plant roots and more vigorous growth.

Why and How to Collect Rainwater for Houseplants
3. 100% Soft Water

Unlike tap water, rainwater is always soft, meaning that it’s free of salts, treatment chemicals, and unwanted pharmaceuticals that make it into the municipal water supply. A regular infusion of rainwater can flush away toxins that build up in potting soil to keep it refreshed for better growth.

4. Naturally Acidic

Rainwater tends to be slightly acidic, which provides a welcome balance to water from the tap. Many cities treat their water to make it alkaline so as not to corrode metal pipes, which can make potting soil unbalanced over time. Adding rainwater to your plant care routine works to rebalance the soil pH for better growth in the long run.

Why and How to Collect Rainwater for Houseplants
5. Organic Material Might be Present

Depending on how you collect rainwater, there’s a good chance it contains traces of organic material. This might include leaf debris, pollen, bird droppings, and other materials teaming with microbial life. Use it to water your plants, and they will benefit from a light application of fertilizer in the process.

Why and How to Collect Rainwater for Houseplants
6. High Concentration of Nitrates

Rainwater is flush with nitrates, which is one of the critical macro-nutrients responsible for plant growth. Without adequate nitrogen, plants struggle to develop lush foliage and produce new leaves. That’s the reason why your grass often appears greener immediately after a good rainstorm.

Houseplants aren’t exempt from these nutrient needs. Give them regular drinks of rainwater, and you’ll see impressive growth because of it.

How to Collect Rainwater for Houseplants

Understanding the value of rainwater for your indoor plants and ensuring that there is always some accessible are two separate matters. Without the right rainwater collection system, you will likely only have small amounts available at a time, or the water you do collect might start growing more microbial life than you want.

Why and How to Collect Rainwater for Houseplants

Here are three strategies for water collection to ensure you do things right:

1. Set out a bucket before a rainstorm: By far the simplest way to collect rainwater is to set out a collection bucket before it falls. You can even add a rain gauge to track precipitation levels. After the storm, bring the rainwater indoors and disperse it between your pots.

Why and How to Collect Rainwater for Houseplants

2. Set up a rain barrel: Make water collection easier on yourself by doing it automatically with a rain barrel. Most connect directly to your home’s gutters so that the water flows directly into a covered barrel. It may have a spigot near the bottom so you can access water when you want it, or you may need to lift the top off to dip in a watering can.

Why and How to Collect Rainwater for Houseplants

Note: It’s essential to set up a screen on top of the rain barrel to ensure you don’t create a breeding ground for mosquitoes and other insect larvae.

3. Collect Snow and Ice: When you’re experiencing winter weather, it’s possible to harvest snow and ice to use indoors for your houseplants. This frozen precipitation offers the same benefits as rain, and it’s easier to collect. Make the process easy on yourself by scooping some in a bucket and pouring it on your plants after it melts.

Note: Make sure the water reaches room temperature before you use it to prevent shocking the plants.

Why and How to Collect Rainwater for Houseplants
Storing Rainwater for Plants

Rainwater is filled with organic material, which means it can start to grow algae and otherwise become contaminated within one week. You can extend its life by keeping it out of light and away from insects. This might mean a dark cupboard or backyard shed. Painting outdoor rain barrels block light from coming in the tanks and will slow down algae growth within them.

It’s also wise to thoroughly clean rain containment buckets between batches to minimize the risk of microbial contamination between them.

Some people prefer to treat rainwater with chlorine tablets to kill off microbial life. However, chlorine can harm plants, so make sure you wait at least 24 hours after treatment before using it for watering.

Collect Rainwater for the Benefit of Indoor Plants

Collecting and using rainwater for indoor plants is far more involved than merely turning on the tap. However, your extra effort will be rewarded with healthier, lusher plants and more vigorous growth. Take the time to give your houseplants a taste of the outdoor elements, and the results will be hard to surpass.