I know the true, precise answer will vary depending on strain, medium, lighting, etc. etc. but.... generally speaking.... on average....... how much liquid does one normally water an 'about to be put into flowering' size plant housed in a 5 gal container? Is it more or less than a 1/2 gal?
You water until you get runoff, that's the amount. When you do water, especially a good-sized pot like that, don't pour it all in at once (I hope that's obvious), pour some and let it soak in, then some more, and so on.
I always water a little bit past where i start to get runoff. i've heard this helps prevent excess salt buildups that are hard to remove
Yes GreenMan, you don't water up until the very first drop of runoff and then stop, you do want a good bit to run out which ensures the soil is indeed soaked through and also gives a little flushing action to cleanse the soil.
Also a good tip on watering in 5g pots is to water in stages... give it like 1/3 the water every 10 minutes so the soil get fully saturated, and it doesn't all drain thru
i've noticed this too. if you have multiple plants it seems to ensure that all the pots get evenly saturated. first time i watered i did it really quickly and some pots were more waterlogged than others. so when the time for the next water came around some pots were ready while others were still wet. make sure you saturate the soil completely, in stages, until you get a little runoff. perfection