When - how often
- how much - these are the questions.
'When' is best answered by watering when the compost is dry, but not bone-dry - then water
copiously. That procedure imitates nature whereas a little water now and then does not.
Most growers cease watering about mid-October and plants remain dry over winter until growth
re-starts about April.
In the Spring when watering resumes, there may be a problem of the compost having dried out -
even gone hard. Some growers use a very small amount of 'wetting agent' (a mild washing soap) for the first and
maybe second watering. Another question is whether rain water or tap water is used. One
argument against rain water is that its purity is uncertain, whereas tap water is known
to be clean. However, rain water is natural, although may contain significant amounts of
carbonic acid, and/or sulphuric acid. Tap water can contain lime which will
accumulate in pots. In summer, watering is usually done in the evening and a fine misting
may be beneficial.
Water condition can affect a compost. Most waters are satisfactory as
suggested above, but hard water can cause compost to cake to the extent
that it becomes almost solid. A normal compost should be friable and easily
break up when handled. When there is no choice on hard water, an old remedy
was to add a pinch of Epsom Salts (magnesium sulphate). Some plants, especially
pot-grown ones, seem to become pot-bound when a hard mat of roots develop
near the surface. Water may not be able to penetrate and just runs off.
The remedy is to cut away that mat, ruthlessly, and the plant will recover
in most cases, if it is done when the plant is coming out of dormancy.
Perhaps knowing that orchid growers often break up a pot-bound plant by
hammering the roots quite hard with a mallet, and then chopping almost
all the roots away with a scissors to the extent that the base of the
plant looks quite bald!! The plants always recovered.