Irrigation of Lavender
Curtis Swift, Ph.D., Mesa Lavender

In most cases, irrigation needs to be accomplished when plants are first set and again be available for those times when insufficient rainfall occurs.  This may require a permanent or moveable irrigation system.

Irrigation can be done with furrow irrigation, sprinklers, drip tape, drip tubing, or microsprays. Some growers hand water their fields. In all cases the soil needs to be wet to the depth of roots and below. Usually making sure 6 to 8 inches depth is adequate. Shallow or excessive watering results in shallow roots subjecting the plants to dehydration as well as increased insect and disease problems. When soluble salts are a problem additional water will be needed to flush the salts below the root system.

Additional Notes:

Subsoil irrigation or under fabric

Your drip system can be placed at the depth of the planting or under the fabric.

Soluble Salts (EC) affect irrigation scheduling

Electric conductivity is a measure of the soluble salts in the soil and/or in the irrigation water.

Plant Establishment

In the early stages, prior to the roots being well established, you need to ensure the native soil and root ball are both moist.  There are occasions when native soil covers the top of the root ball preventing the movement of water into the root ball. This is more likely to happen when your soil contains clay.  Some soils will pull moisture out of the root ball so testing the root ball for moisture is critical.

Irrigation Frequency

Frequency of irrigation and how much water you apply depends on your soil type, and climatic conditions in your areas. For that reason, no one cannot provide you an accurate recommendation on how often to irrigate or how much to water to apply at your site based on how the water their fields. Just because the grower next door is watering at a specific schedule does not mean the soils in your field are the same. Soils in a field often vary with each having different requirements for irrigation amount and frequency. Growers can fine-tine their irrigation needs if they know what soil textures are in their field.

Determine the soil moisture with the soil ball technique

You can use the soil ball technique to fine tune your irrigation as this will approximate the percentage of moisture in your soil.

Keep in mind newly planted lavender will need more frequent irrigation as the roots are still quite shallow and restricted to the root ball area. Checking the moisture content of the root ball with your index finger is helpful in determining how frequently to irrigate. Once roots spread into the surrounding soils your irrigation scheduling will be much easier.


Some land-grant colleges provide local ET data on a daily basis. (See as an example.) If your land-grant college is unable to provide data on the ET at or near your site, there are two great options for you to determine the ET yourself.

Determine soil texture

Soil texture determines the water holding capacity of the soil and when you need to irrigate again taking rainfall into account.

You may already know the texture of your soil, if not Web Soil Survey ( provides the best possible update on the soil textures of many fields. Not all areas of the United States have been surveyed but hopefully your fields are included.

Texture changes with amendments

Amending the native soil can change the infiltration rate and water holding capacity of the soil so you will likely need to make changes to your irrigation as the year(s) progress. As soil settles after planting, these factors may also change.  Double check the infiltration rate and water holding capacity as soil compaction occurs to reassess your irrigation strategy. You may need to do this yearly until the field is established.

Even though your soil may hold 2 inches of water in a foot of depth, not all that water is available for plant uptake. This is where the MAD comes into play. The permanent wilting point is also critical to know. Once the water availability drops to or below this point, the plant will reach its permanent wilting point. This is the point of no return for the plant.