Like humans and animals, plants need both water and nutrients (food) to survive. Most all plants use water to carry moisture and nutrients back and forth between the roots and leaves. Water, as well as nutrients, is normally taken up through the roots from the soil.
So, for example, a 3-month old puppy should be able to hold its urine for approximately 4 hours in a pinch. This means that if you have a properly toilet trained 4-month-old puppy that, theoretically, can hold its urine for 5 hours, and you shut that puppy in a crate for 6 or 7 hours, you are courting disaster.
A good guide is that dogs can control their bladders for the number of hours corresponding to their age in months up to about nine months to a year. (Remember, though, that 10 to 12 hours is a long time for anyone to hold it!) A 6-month-old pup can reasonably be expected to hold it for about 6 hours. Never forget that all puppies are individuals and the timing will differ for each. Monitor daily events and your puppy's individual habits when setting up a schedule.