The amount and frequency of irrigation really depends on several environmental and soil characteristics. It is important to remember the following:
Supplemental irrigation may be needed during rainy periods.
The need for irrigation increases with increasing temperature.
Similarly, windy conditions may necessitate more frequent irrigation.
Poorly-drained, clay-type soils require less frequent irrigation than sandy soils.
Plants with small or poorly-developed root systems are particularly sensitive to moisture deficits.