On 2008-10-14 11:13:54 +0100, "Jeff Layman" said:

Stan The Man wrote:
On 2008-10-12 23:14:39 +0100, JayDee said:

So it seems that some plants like to get completely dry, then flooded
and not watered again until dry - but is there an easy way to
determine which will work best for a particular plant or family? I've
been doing the dry/drench on my ficus benjamina and it has been
thriving! Sometimes I go 10 days before adding a drop of water.
However I tried the same with my bougainvillea and it wasn't so
happy. Creeping fig and grape vines also seem happiest with being
damp all the time...

Other than that, I'm adding a little bit of organic fish and seaweed
fertilizer to every other watering or so.

Another curiousity - I spray the leaves every morning on all the
plants - does that actually help them, or just make them look shiny?

"Little and often" is a bad watering regime since it encourages plants
roots to stay close to the surface of the soil. A thorough drenching
from time to time is the right way to go so that the water permeates
deep into the soil and takes the roots with it.

Water should always be applied to the roots, ie under the leaf canopy.
Spraying water onto leaves can be harmful: in hot sun the droplets can
focus the heat so as to scorch the leaves; and mildew or other fungal
attack is more likely if the leaves are constantly damp. Plants'
leaves are designed to absorb sunlight, to breathe and to shed water
down to the root area. The amount of water they can absorb is
miniscule.

I know that these are the perceived wisdoms regarding watering, but I often
wonder if they are old chestnuts.

Rhododendrons are said to be shallow rooted, but appear to do just fine,
even in a short drought. What happens to deep-rooted plants in areas with
an intermittently high water table? Surely they would be more likely to
suffer root rot than shallow-rooted plants.

Drought may not harm tough plants: their roots go ever deeper in search
of moisture. I wouldn't plant deep-rooted varieties in a place where
their roots might sit in the water table.

Has anyone seen leaf scorch following watering in intense sunlight? How do
equatorial plants survive in climates characterised by intermittent showers
and tropical sun?

My friends who garden in the south of France will definitely get
scorched leaves if they water in the heat of the day so they do all
their watering between 5-6am. Of course, this also minimises
evaporation loss.

Agree about the fungal diseases in damp atmospheres. Trouble is, do you
prefer fungal problems or red spider in greenhouses?!...

Different rules for greenhouses - at least for tropical plants...