California Native Plant Watering Guide

Native plants grow during the rainy season.  Until established all natives need to be watered for a few seasons, about two years.  Natural gardens use less water than a traditional garden and can save about 90% of water.  

Water is used by plants to grow and cool themselves.  Soil stores water where plant roots can find it.  Most plants absorb water through their roots while some can absorb water through their leaves.  Native plants need to be watered before the plant needs it.  To achieve this the plants need deep infrequent irrigation.  

Over watering will cause root rot.  During the summer when temperatures are warm natives need oxygen in their root zones.  Root rot will most likely infect the plant during warmer months when the plants have too much water and not enough oxygen.  If your soil is moist or wet you do not need to water.  

You should deep soak the plant when the top four inches of soil is dry.  New plants will need to have a deep soak more often but not every day.  Below are a few methods to watering your plants.

Deep Cycle Soaks resemble a natural rainfall- For heavy clay soils deep soaks in a cycle are beneficial to the plant because penetration is difficult and absorption is slow.  You should water three days in a row and try to obtain at least 1.5 inches of total irrigation.  This method allows for better oxygen, penetration, and root uptake.  

Hand watering with a wand is a great way to slowly soak plants.  You should hand water early in the morning or early evening.  This will allow you to spend time in your garden and watch the plants.  You should water once a month with sprinkles once to twice a week.  

Sprinkle is washing the leaves, moistening the soil surface, and cooling the area around the plant.  You can achieve this with a water wand or running the sprinklers for about five minutes.  Sprinkles do not effectively water the root zone or promote long term sustainability.

Sprinklers are a great way to soak plants.  It is best to use a sprinkler with low water flow.  A low volume flow provides a deep soak, the small droplets prevent soil compaction and help keep the leaves dry.  Sprinklers with a low volume flow release about a quarter inch of water an hour.  It is possible that you will need to water for up to twelve hours to achieve a deep soak.  To determine the precipitation rate, place empty cans around the watering area for 30 minutes.  To understand the average inches per hour measure each can and make an average, multiply by two because you watered for half an hour.  You should aim for about 2 inches of water per irrigation cycle.  Established plants should be watered once a month and achieve 2 inches of water.  New plants should be watered twice a week for five minutes in addition to deep soak irrigation.        

Drip Irrigation is a great method for achieving a deep soak.  Drip lines are usually hidden under a layer of mulch.   It might be difficult to sprinkle the plants unless there are also sprinklers or you manually use a hose.  Ensure the root zone is thoroughly and evenly soaked.  Some people experience issues with drip systems- they do not run the water long enough and have few emitters that are placed too close to the plants crowns.  You will need to understand the drip systems precipitation rate to achieve two inches of water.  Water is measured in gallons per hour because of the low flow rate.  Avoid placing emitters near the crowns of the plants, this could cause crown rot.  Install enough emitters or set the grid to wet all soil where the roots will grow.  Water moves down the soil by gravity and capillary action, and laterally by capillary action.  Capillary action is when the soil particle holds water on its surface and passes free water to the neighbor soil particles.  Capillary action helps evenly distribute water throughout the root zone. To effectively design an efficient drip system you need to calculate soil type, the soils water holding capacity, and capillary action.  To test that the drip system is working you should dig a hole 4” deep and see if the soil is dry, wet, or soggy.  As your plants grow you will need to adjust the emitters to move them farther away from the crown and add more.  This should be practiced every six months for about two years.    Ensure that water runs away from the crown.  The deep soak needs to be outside the base of the branches.  

Water where the roots are and where you know the roots will be when the plant matures.  The root zone is the most active in the zone where the outermost branches are.  You should avoid watering the crown.  Watering the crown could result in fungal rot.  

Ensure that new plantings root ball does not dry out.  You should also promote root growth by watering around the plant.  

Once plants are established you should water the ground consistently, mimicking a rain fall, a deep soak.  

For the first 3-6 months of a new plant you should deep soak every three to four weeks in the early morning.  If you have a higher evapotranspiration you should deep soak every two weeks.  In the summer a deep soak should be done once a week.  Refreshing sprinkles should be done about twice a week.  If you are using a sprinkler you can run the sprinklers for about five minutes.  The plants appreciate a sprinkle in the late afternoon.  Do not water in the heat of day and preferably not during heat waves. Water ahead.

Once your plants become more established, about 6-18 months you should deep soak the plants about once a month and achieve two inches of water.  The water should be about four inches away from the original planting hole.  Refreshing sprinkles should be done about once a week.  If you are using a sprinkler you can run the sprinklers for about five minutes.  The plants appreciate a sprinkle in the late afternoon. Do not water in the heat of day and preferably not during heat waves. Water ahead.

Mature plants that are fully established should be deep soaked every month and achieve two inches of water.  Refreshing sprinkles should be done every ten days.  If you are using a sprinkler you can run the sprinklers for about five minutes.  The plants appreciate a sprinkle in the late afternoon. Do not water in the heat of day and preferably not during heat waves. Water ahead.

Different soil types:

Clay soil retains water longer but slowly absorbs water.  Sandy soils dry out quicker.  Loam soils retain more moisture and have more space for oxygen.  You will have to water sandy soils more frequently than clay.  Water exits the soil through evaporation and the plant roots.  You will also have to water more frequently in dry and hotter conditions.  You should always plant plants together based on their soil preference.

To understand what type of soil you have you can conduct two tests.

Percentage of sand, loam, and clay by filling a clear mason jar halfway full with dirt.  The soil should be taken about ten inches deep (the length of the root ball in the soil).  Put in a few drops of dish soap, fill the jar with water about one inch from the top.  Shake the jar.  Sand should sink to the bottom because it is the heaviest.  Silt will rise above the sand within a few hours.  Clay will rise above the silt in about 24 hours.  Measure each layer with a ruler and calculate the percentage of each.   The soil pyramid below will help you determine your soil type.

Dig a hole 14” deep and 16” wide.  Fill the hole halfway with water.  If water drains out quickly you have sand.  Mark the water level and come back in an hour.  If water has not been absorbed then you have clay soil.  If your water has lowered an inch or more then you have loam.  Loam is a mixture of 40% sand, 40% silt, and 20% clay.