Ideally one should apply water at a steady rate, in effect at a rate that emulates steady rainfall.
Too much water at once can cause soil erosion and compaction, plus it can wash away nutrients.
There are many types of equipment available to the amateur gardener for applying water to the soil, each with there own benefits and / or drawbacks, here are a few.
These can come in varying sizes / capacities although the two most popular are the 1 litre (1¾ pints) and the 10 litre (2 gall) sizes.
Watering cans usually come fitted with either a coarse or fine spray rose.
The main advantage of the watering can is that each plant is more likely to get an amount of water relative to its needs, and the surrounding area is left dry, wich can act as a deterrent to slugs and snails.
Before using these one must ensure that there is no hosepipe ban in your locality.
While this method of watering is more convenient, it is often more wasteful, and sometimes damaging!
What can happen is that some plants get more water than others, and non planted areas get watered as well, thus encouraging weed growth!
Add to that, the wetted area makes a good skid pan for slugs and snails to navigate to your plants.
There are a number of hose end attachments that can be fitted to hoses that allows the user to vary the intensity of the spray.
If the intensity is too great, you can damage plants, spoil flowers, damage the soil surface, and wash out nutrients.
Similarly the water may run off the designated area before it has a chance to percolate down to the root system.
They have limited use on flower or vegetable beds due to the expanse of the spray, that is, the water goes on to areas that might not necessarily require watering to the detriment of the areas that do, meaning they use huge amounts of water.
Leaking / Seeping /Trickle hoses:
If laid on the surface the hose is laced around randomly planted plants, or placed adjacent to rows of plants where the water seeps out and percolates down to the root systems.
In both cases it is possible to fit the hose/s to reservoirs that allow soluble liquid feed to be added into the irrigation system.
Similarly these hoses can be fitted with automated watering systems where an electronic timer is screwed to the tap to turn the system on/off automatically.