There’s nothing quite like rainwater. When it comes to organic growth, it’s important to remember soil is alive: favorable conditions for microbes mean favorable conditions for plant growth. Is there anything wrong with the water that comes out of your faucet or hose? Not really. Despite additives like chlorine and fluoride, plenty of adequate crops are grown with tap water.

However, not all drinkable water is the same. Growers using hydroponic systems with synthetic nutrients tend to opt for reverse-osmosis (RO) or distilled water. Without a host of critters to act as pH buffers, precise consistency of water purity and pH are necessary to maintain a healthy environment. These types of water are thoroughly filtered, and contain virtually no impurities.

Rainwater on the other hand, is much more than just water. The pH and composition varies seasonally as well as by region, but rain that falls over a given ecosystem is essentially tuned to that local environment. There are no pH-adjusting solutions to mix in nature; the soil microbes have that role. While plants need a few main nutrients to thrive (nitrogen, phosphorus and potassium), they also need a handful of secondary nutrients in much smaller quantities-such as calcium and magnesium.
These life-sustaining compounds are found in rain, making trapped rainwater a prime choice for marijuana soil. Seasoned organic gardeners know: you don’t feed your plants, you feed your soil! The soil will take care of your plants for you, and rainwater can be a great way to keep that soil healthy.