Containers in the Rain

sub_irrigationContainers in the Rain
By Susan at Nature’s Footprint

I was recently asked a question about rainwater and its impact on container gardening. The question was presented by one of our loyal users of the Metro-Grower™, a gardening container designed to be watered from the bottom up. There was concern the rainwater might wash away all the valuable nutrients in the potting mix.

Fortunately, the Metro-Grower has a large, deep saucer that will contain most water as a result of rain. The nutrients will then be returned to the plant through the sub-irrigation design. Conversely, if your container does not have a saucer and adequate drainage holes, you may find your plant drowning when heavy or persistent rain falls and actually losing valuable nutrients.

Are there benefits to rainwater? To answer this question, a little research was required. First of all, rainwater is free of chemicals such as chlorine and fluoride often used in municipal water systems. These chemicals are harmful to any plant. Rainwater is also free of salts found in water processed through water softening systems – another danger to plants. And, rainwater contains nitrogen, especially rainwater that falls during a thunderstorm – plants thrive on nitrogen.

Rain also removes dust from plants enabling the plant to more efficiently collect solar energy through the process of photosynthesis and convert it into the chemical energy the plant needs for growth. Water from your garden hose, when used to rinse your plant, is comparable to giving your plant a shower in a weak bleach solution – not good! If chemical fertilizers have been used on the plant, the rainwater will also aid in driving the salts down and away from the roots allowing for better root growth.

Negative aspects of rainwater If you are in an area with industrial pollution caused by the burning of hydrocarbons, this can result in harmful chemicals such as sulfuric acid being released into the atmosphere. This can cause “acid” rain and result in extreme damage to the leaves of plants and alter the chemicals in the soil.

Simple answer No, rainwater is not harmful to plants grown in well-drained containers (unless it is acid rain). In fact many gardeners collect rainwater for use on their plants. Since this practice may be illegal in some states, we suggest you check your state regulations before investing in a collection system. Sounds like a future story!