Watering plants with rainwater or tap-water
Water is indispensable for your plants; without water they simply will not grow or flower. But which kind of water is better? Rainwater or tap-water?
Plants prefer rainwater
The answer is hardly difficult: rainwater wins, as it contains less calcium and chlorine and more minerals and trace elements than tap-water does. Especially acid-loving plants such as azaleas, heather, rhododendrons, magnolias and skimmias prefer rainwater. Fortunately these are garden-plants and as a rule get rainwater only. However, during periods of drought you had better water or spray them with rainwater or groundwater instead of tap-water. Another advantage of rainwater is that it is always at the right temperature for your plants, whereas cold(er) tap-water may cause some to serious stress.
Should you use soft tap-water or demineralised water when growing plants, Calmag is a sound, extra supplement to regular fertilizers as it provides plants with extra calcium and magnesium.
How to water houseplants
In general, houseplants do quite well on tap-water, but when given the choice they would prefer rainwater, particularly those plants you need to spray once in a while, like ferns; they really thrive when given a ''rainwater shower'' (of fine droplets). Another disadvantage of tap-water is that terracotta pots may partly turn white caused by calcium deposits in tap-water.
Storing rainwater for your plants is not only beneficial to your plants but also to the environment. Contrary to popular belief tap-water happens to be rather expensive drinking water, even though in our part of the world its price is relatively low. Yet, the process of extracting water from the soil and purge it from all sorts of impurities is a costly affair. So it's highly regrettable to use (or even misuse) this water, for instance by watering your plants with tap-water when rainwater is plentiful. Especially in periods of drought one discovers how valuable rainwater is. In short, watering with rainwater is better for your plants and for the environment.
To be able to water your houseplants with rainwater you need to store it first. Fortunately all sorts of storing solutions help you to do so in an efficient and even modestly decorative way. Take, for instance, a wooden (or plastic) rain-butt. Simply disconnect a drain-pipe and put the butt underneath. A whole range of butts is available, presented under different names like ''rain-column'' or wall-tank. A rain-column is a large butt formed like a column (so: slender and tall). A wall-tank is a small butt which you simply connect to the wall beneath a gutter; making it ideal for small gardens! Another option is to bury a butt and lead the water towards it, so it will not flow into the sewer and be lost to you, but is safely stored underground. In order not to burden the sewage-system unnecessarily you can save rainwater directly in the garden by creating a wadi (a lower located part of the border or lawn, serving as a water buffer zone). Or by directing the water to a low-lying piece of garden lined with anti-root fabric and filled with grit, allowing water to drain slowly into your garden.
By storing rainwater you actively contribute to less flooding during heavy rainfall, for when it absolutely pours with rain, sewers quite quickly fail to cope with the massive influx of water. By restricting hard surfacing in your garden and allowing as many plants, shrubs and trees as possible, your garden will absorb much more rainwater. And that really will make a big difference to prevent flooding and overloaded sewers.
Read on about what action to take in your garden during damp and rainy conditions