Watering your plant material is very important. However there are a few factors that will determine how much water is needed and how frequently you should be watering.
The two primary factors are: weather conditions and soil conditions. Check soil conditions before watering.
Always check the soil to determine if water is needed. If the soil is dry at 4 to 7 inches deep, you should apply water. Generally, sandy soils will need moisture more often then any other type of soil, but always check before watering. Water thoroughly so moisture penetrates the soil.
Plant roots will seek out moisture below the surface. Deeper roots enable plants to absorb moisture from farther below the surface, even when top soil dries out. With deeper root systems you get stronger, healthier plants. Avoid frequent, light watering. Roots go where the water is.
Frequent, light watering keeps the moisture near the surface and causes shallow root systems that are more vulnerable to weather conditions, especially heat and heavy rain.