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How to use irrigation Schedule 1 for low water use plants


Water is essential to the growth and health of our landscape plants. Over 97% of water used by plants is needed to cool their leaves and stems; the remaining water is needed for growth of roots, stems and leaves. In nature, this water comes from rainfall; in gardens we commonly provide supplemental water with our irrigation systems.

Supplemental water needs variables

The amount of supplemental water we apply can vary throughout the year and is mostly influenced by the types of plants, seasonal climate, microclimates, soil types.

Our garden plants come in many different sizes and shapes. Plants that have the most leaves often need the most water for cooling. This means our trees often need more water than smaller shrubs and ground covers. Succulents and cacti have an advantage by storing water in their stems for use when conditions are dry. Many California native and Mediterranean plants have adapted to summer conditions with leathery leaves, and also by becoming inactive when soil conditions are dry.
Due to the many types of plants we can grow in our gardens, we recommend selecting and combining plants with similar water needs together and applying appropriate amounts of water to each group. This technique leads to different garden moisture zones, or hydrozones, that can be watered on separate irrigation valves.

Seasonal water use

As might be expected, we apply the most water to our gardens from April through October after winter rains are finished and when the days are longest and temperatures highest. We also provide more water to plants growing in sunny areas and when they are flowering. Less supplemental water is needed in the winter months when temperatures are cooler, days are shorter and when we have seasonal rains.

Irrigation Schedule 1 moderate water use plants

Irrigation Schedule 1 has been developed for Low Water Use Plants that need limited amounts of supplemental water during the summer to grow well in the Inland Empire. These plants include many cacti and succulents, and various California native, Southwestern and Mediterranean plants. Plants included in Irrigation Schedule 1 are among our most drought adapted choices for our landscapes and gardens. The Irrigation Schedule and Graph shown below, has been designed to provide you with the baseline amount and frequency of supplemental irrigation water on a monthly basis for established gardens with these plants. Winter rains can provide winter water from November through March, but we need to provide supplemental water during our long hot and dry cycle of the year.

An Irrigation Schedule and Graph has been prepared for four different groups of plants depending upon their supplemental water needs. Supplemental water is organized on a monthly basis as well as volume and number of irrigation applications. The objective is to water deeply and infrequently. Again, we want to add moisture to the top 12-15 inches of soil where possible and to encourage deep root depth within our plants. In practical terms, we try to provide at least 1 inch of water each time we irrigate, and we will water one, two, three or four times a month depending upon the water needs of our particular plants.

Each baseline schedule and graph is a recommended starting point for your garden water needs. However, it is always necessary to study your garden conditions and adjust this schedule to fit the seasonal and microclimate variations, including heat waves, droughts, and winter rains (that can provide all the winter moisture needed so your irrigation system can be shut off). This requires you to be vigilant and make garden observations and adjustments to this baseline schedule for it to work best for you.

Scroll horizontally to see the full table

  Jan* Feb* Mar* Apr May Jun Jul Aug Sep Oct Nov* Dec*
Runs per Month 0x to 2x 0x to 2x 0x to 2x 1x 1x 1x 1x 1x 1x 1x 0x to 2x 0x to 2x
Inches per Run 1" 1" 1" 1" 1" 1" 1" 1" 1" 1" 1" 1"
Inches per Month 0" to 2" 0" to 2" 0" to 2" 1" 1" 1" 1" 1" 1" 1" 0" to 2" 0" to 2"

Range of supplemental summer water: 7"
Range of supplemental winter water: 0"-10"

  Jan* Feb* Mar* Apr May Jun Jul Aug Sep Oct Nov* Dec*

Look at Irrigation Schedule 1 above. For plants assigned to Irrigation Schedule 1 we have provided you with a chart that shows how many times to water each month (Runs per Month) and how much water to apply during each application (Inches per Run), and the total amount of monthly supplemental water (Inches per Month) needed to sustain these plants.

As you can see, monthly supplemental water needs for plants assigned to Irrigation Schedule 1 need only 1 inch of supplemental water from April through October. In contrast, these plants grow best with when we have good winter rains; if these rains do not occur we should irrigate up to 2 inches to make up for the lack of rainfall. This chart also indicates to apply 1 inch of water during each irrigation cycle.

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