Collecting rainwater with gutters and downspout into a rain barrel is not only an economical way to water your plants, it also helps to protect the greenhouse structure.
Moreover, rainwater is better than tap water for plants because it is not treated with chlorine as tap water to make it safe to drink. Also, rainwater is soft and during thunder storms it contains nitrogen essential for plant growth.
Let’s look at other advantages of rainwater for plants.
Why do plants grow better with rainwater?
Reason 1 – Tap water is treated with chemicals. In comparison to tap water, rainwater is pure because evaporation gets rid of the chemicals. Depending on the region you live in the composition of tap water is different. It varies according to the filtering system and water softeners.
Reason 2 – Rainwater is soft. Naturally, the water from the sky is soft. So it only contains sodium ions. Once the water reaches the ground it absorbs minerals such as chalk, lime, calcium and magnesium. This water is then softened in the public system to be suitable for drinking.
Most of the time after the softening tap water is still considered hard because minerals like calcium and magnesium are present. Although it is good for drinking, high amounts of these minerals can affect soil’s pH.
Also, when watering plants with tap water you can see white deposits on the surface of the soil which account for excessive calcium.
Reason 3 – Rainwater is slightly acidic (pH 5.6). It is beneficial for plants as they absorb nutrients from the water when soil’s pH is slightly acidic. In contrast, most of the time the pH of tap water is alkaline which is not healthy for the soil and plants.
Reason 4 – Rainfall contains nitrogen which is essential for plants growth. During thunderstorms lighting adds nitrogen to rainwater which is vital macronutrient for the production of chlorophyll. Plants on its own are not able to pick up nitrogen from the atmosphere and take it from the soil.
However, plants can absorb nitrogen from the atmosphere during high-energy processes like lightning.
How to store rainwater for plants?
To store rainwater for plants you need to make sure that you clean water barrels annually to prevent fungal diseases. Due to the fact that it mostly rains in winter, you can collect it and store to use in summer.
Get a water barrel with a lid so debris won’t get in and it will also prevent water from spilling. I would recommend cleaning the gutters regularly because rainwater will pick up dirt from them and build-ups which can be dangerous for plants when watering, especially for seedlings.
How long can you store rainwater for plants?
The rainwater itself is clean and can be stored forever, the main concern is how to store it and prevent from contamination. The first thing to consider is having regular clean-ups of the gutters. Rainwater going down the gutters that are dirty and clogged is likely to cause diseases in plants.
Following the advise on the rainwater storage above, in addition to having an annual clean up of the water barrel, I would recommend to assess the water and the barrel every 3 months.
Drain the rainwater into a clean tank, you can also use the filter to get rid of any debris. Sterilize the drained barrel and it is ready to collect rainwater further.
How to collect rainwater?
To collect rainwater from the greenhouse structure you need to install gutters to drain the rainwater from the collecting channels down the downspout to a water barrel.
Some of the greenhouses come with the built-in rain gutters so you just need to connect a thin PVC downspout which is going to direct rainwater into a barrel.
You can get a 55 gallon rain barrel made from polyethylene, for example, this option comes with the lid which has a metal mesh filter to prevent debris and mosquitoes from getting into the barrel.
When choosing a water barrel I would recommend buying a water barrel which can be connected to other barrels to increase the rainwater storage. Make sure that it comes with the spigots at the bottom so you can fill the watering cans right away or connect the watering hose.
Alternatively, you can get Rain Catcher Barrel which already comes with the garden hose which can be attached to the barrel with a hanging hose clip.
How to make tap water safe for plants?
In a process of softening hard water, most of the time when it boils down, it removes all of the minerals like chalk, lime, calcium and magnesium. However, the amount of sodium increases. High levels of sodium can build up in the soil throughout the months.
Also, tap water is treated with chloride to make it safe for drinking but it can be damaging for plants. If you keep watering plants with tap water high in chloride, it can affect the amount of nitrate plants absorb from the soil.
In addition to high amount of sodium and chloride in tap water, it most of the time lacks nitrates as these tend to cause blue baby syndrome in babies.
So, is there a way to make tap water safe for plants?
First, you need to identify if the tap water in your home is hard or soft. Hard water contains high levels of calcium and magnesium while soft water is high in sodium. In both cases you can fill up the watering can with water and let it sit for a day before actually using it.
That way the minerals will go down to the bottom of the watering can and you can water the plants leaving approximately 1 inch of water at the bottom. It is the most economical and efficient way of making tap water safe for plants.
