A very general rule of thumb is to provide lawns with 1 to 1.5 inches of water per week, from irrigation or rainfall. A good way to check moisture penetration is to probe the soil with a screwdriver or similar object. How often you water will vary based on where you live and what type of soil you have.
Grass Type
Different grass types require different amounts of water. For example:
- A healthy lawn of tall fescue has a deep root system and the highest drought tolerance of cool-season turf types.
- Kentucky bluegrass consistently goes dormant during drought, reviving when rainfall resumes.
- Warm-season grasses, such as zoysia, St. Augustine, bermudagrass, and centipede, thrive in warm conditions, developing deep root systems that make them better able to withstand drought. In general, warm-season grasses require 20 percent less water than cool-season types.
Soil Type
Different types of soil absorb and retain moisture differently.
| Soil type | Water absorption | How deeply 1 inch of water penetrates |
|---|---|---|
| Sandy | Absorbs water quickly; needs less water more frequently | 12 inches |
| Loam | Absorbs water evenly, without puddling or runoff | 7 inches |
| Clay | Absorbs water slowly; can cause runoff when water applied too quickly; holds water longer (slow to dry out) | 4–5 inches |
Healthy grass roots typically grow at least 6–8 inches deep.
Regionality
Different regions receive different amounts of rainfall and summer weather conditions, which influences irrigation needs. Grass needs the most water when heat, drought, low humidity, and high winds prevail. Learn to identify signs of drought and summer lawn stress.
Lawn Age
There’s one other key when determining irrigation frequency. While all lawns need consistent moisture to remain green and healthy, newly planted lawns are in a critical stage for the first year. Don’t rely solely on rainfall to establish a healthy, deep root system – provide supplemental irrigation during the first year of growth.