as it goes know plants like water on there leaves and generaly the water runs of mostly of all leaves .the leaves are for the sun and the roots need the water.the best way of watering i find is to put the hose on the ground and move it about as often as need be rather than a sprinkler .this works well for me.the only thing for sprinklers is lawns .water that does stay on leaves can burn them in sunshine.

Rules of thumb for sprinkling plants:

#1 Use pure water. Salty or very hard tap water often causes more problems than benefits. If you have to, follow Rule #3 religiously. This probably explains why many plants can stand out in the rain all season, yet shy away from the hose!

#2 Don't do too often. Frequent sprinkling spreads many fungus diseases--such as rust or black spot--and creates a friendly home for some pests, such as snails and slugs. The main exception is when treating for spider mites.

#3 Be generous. When you do sprinkle, sprinkle long enough to produce a fair amount of runoff from the foliage. That's the best way to remove dust and dirt from the leaves and young leaves, and also removes the salt and alkali from the last sprinkling.

#4 Do sprinkle early in the morning. Sprinkling in the heat of the day can cause unwelcome rapid fluctuations of leaf temperatures--Rule #3 can ameliorate that somewhat. Sprinkling in the evening can leave water on the leaves and/or high humidity all night long--made to order for some fungi, such as powdery mildew.

Injuctions to avoid water on the leaves of Nicotiana probably stem from its susceptibility to powdery mildew. Over all, I would use ground soaking for the main watering of the plant, and only sprinkle to cure or prevent known problems. Note that in dry climates, junipers, cypresses, "cedars", and arborvitae love to be hosed down vigorously on a weekly basis: it prevents spider mites reliably!

great minds think alike Tugbrethil

Getting too professorial again! Sorry!

thats quite alright better than not enough info mate