Stephen, for containers the best time to water is when you get to it :-) Time of day really doesn't make any difference since you should only be watering just the soil/potting medium and not the foliage.

I water until it drains freely out of the bottom of the pot. And then I wait to water again until the soil is quite dry for the first few inches. If you are using a freely draining potting soil it is hard to overwater......but it IS possible. In our dry summers, I water every second to third day but all my containerized maples are in pretty big pots. Smaller containers may need more frequent attention but it all depends on your climate and natural rainfall, providing they are in a location that is freely exposed to that.

Underwatering can show as spotting or dry edges on the foliage or the drying and browning of the foliage. Overwatering often shows up first as wilting but without the dryness or browning. That can follow. Neither is good but if I were forced to choose, I would go with underwatering - as long as it is not an extended period, most JM's will bounce back from that pretty rapidly. Overwatering leads to root rots and those are much harder to recover from, if at all.

Thanks for that Gardengal

It seems the Potting Medium for Containerized maples is Vital in order for the Water to run out Freely from the Bottom of the Pot.I'm sure failure to do so would result in Water becoming trapped in the Potting Mix therefore endangering the Root System and indeed the Life of the Tree.

Would you suggest 1/2"+ bark chippings in the Potting Medium for say a 15 Litre Pot ?

Regards,Stephen

Yep - 1/2" bark fines is pretty much ideal :-)