Those of you who may have been worried about the Orchid Project running out of rainwater during our long dry summer (or is that just me) can relax – our tank is full again.
Our 16 000 litre tank, seen here under today’s stormy skies, holds enough water for about eight weeks of watering and by the end of term was down to its last week’s worth of precious rainwater. Fortunately a good wet weekend like the last one results in more than 16 000 litres of rain falling on the greenhouse roof (that is 8cm of rain) and we are now sorted for the summer.
Thanks go to the girls in 2009 who calculated how much storage we needed to build for the new greenhouse, your calculations have been spot on.
We use rainwater for all our watering for three reasons:
1. Tap water in the Mendips is very hard and would cause white lime scale marks on all our beautiful glossy green leaves.
2. The dissolved salts in local tap water give a conductivity of 500 micro- Siemens which is close to the limit of what many orchid roots can tolerate. Using rainwater, conductivity 20 micro-siemens, allows us to add plant food without taking the conductivity of the water up too high for roots to cope with.
3. 2000 litres of water a week is a lot of water and it is a pleasure not to be using scarce and metered mains water.
For tropical plants it is now the wet season – time to splash the rainwater