Watering is one of the most important factors in the health and longevity of a California native plant landscape.  Inappropriate watering is the primary reason California native plant gardens fail, and can cause quite a bit of frustration for those who are unaware.  Learn why designing for rain water capture will set your landscape and plants up for success, and how to water new and old plants.

Design with strategically placed moist areas

If you look at nature, the healthiest, most beautiful natural locations often have a moist area such as a seasonal creek nearby, and you can mimic this in your own garden.  As you are designing your garden, put any riparian plants inside any regularly irrigated or naturally moist areas you might have, and the drought tolerant ones in drier areas a little farther away.

Allowing the drought tolerant plants to stretch their roots out to adjacent moist areas is the best way to help them stay a little greener in the summer.

You might also want to create a few irrigated hollows, catch basins or seeps strategically placed around your garden.  They’ll capture more rainfall and minimize runoff from your property too.

It’s often a good idea to irrigate the areas closest to your house and place riparian plants in those areas, especially in fire-prone parts of the state.  They’ll be very resistant to burning.  Over time, the plants in the drier parts of your garden will reach their roots out to the moister soil and stay greener year round using the natural irrigation system they evolved to use.

Credit Jim Brugger.
Credit Jim Brugger.

Watering New Plants

Once the plant is in the ground, build a small irrigation berm around it, and generously soak it.   (The initial soaking is probably the only time you can’t water most native California plants too much.)  After that first watering, take down the irrigation berm so subsequent watering doesn’t make the soil too soggy.  Flat areas around the plant are fine, but make sure the plant is not in a basin or it will likely get waterlogged and die.

It’s important to keep the root ball moist but not soggy during the first three months after planting.   During the rainy season, you might not have to water at all, but if there’s no rainfall after planting, you’ll probably have to water 1-2 times per week during this period.   After the first three months, start less frequent, but deeper watering.  Make sure the root ball is only slightly moist before each new deep watering, usually every 2-3 weeks if there’s no rain.  Then give it a good soaking.  During the rainy season, you can usually rely mostly or entirely on natural rainfall.

After the first year, and after it’s doubled in size, the plant should be fairly established.  If the plant is properly sited, you should be able to cut watering back to once per month or stop artificial watering entirely.  When you do water your plants, it’s always best to water in cooler temperatures.

Once your plants are established in your garden, it’s usually best to avoid all direct artificial irrigation.  Most established non-riparian native plants can’t stand prolonged warm and wet conditions.  These conditions often cause soil borne pathogens to get out of balance and can kill a healthy plant in days.  Younger plants need more water, and are more tolerant to warm and wet conditions than older plants.  But the older a drought tolerant California native plant gets, the more susceptible it tends to be to warm and wet conditions.  So reduce watering over time between the first and second year after a plant is installed.

Watering Established Plants

If you are growing California native plants in their natural geographic range and they are properly sited, your drought tolerant plants should be able to thrive entirely on rainfall.

They might look a little brown and drought stressed in the summer and early fall, but that’s natural.  Water conservation is one of the key benefits of gardening with native plants.

However, most drought tolerant natives (and all riparian natives) can handle occasional light irrigation in the hot summer and early fall, and if you are careful, they’ll probably look a little greener and prettier with just a little bit of water.  But again, be careful.  Improper irrigation is probably the biggest reason – after poor plant selection – for why some California native gardens fail.   Here are some basic tips:

  • Drip Irrigation
    Avoid single point source drip irrigation.  It will typically train your plants to form a tiny root ball near the drip, and they’ll never end up developing the broader and deeper root system they’ll need to get through the warm summer months.  Even worse, summer drip irrigation directly on the root ball fosters the soil pathogens that can kill established drought tolerant California natives.Drip irrigation can still produce great results if proper methods are used.  Try using several drip emitters per plant and stake them down with sod or jute staples so that they irrigate no closer than the dripline of a plant and not at the base of the stem/trunk.  Inline emitters like Dura Flo JR create a more even watering zone as they can be easily looped a few times around the drip line of a plant & staked in place with a jute staple   They have emitters spaced every 6 inches. and irrigate the soil slowly, evenly and efficiently.  As your plants mature, move the drips or inline emitters farther away so your plants will extend their roots away from the sensitive root ball towards the moister soil.
  • Overhead sprinklers
    Use overhead sprinkler systems cautiously.  Many people already have overhead sprinkler systems in their garden, so this might be your only practical solution.  If you are using automatic irrigation, set watering times to start in the early morning and finish before sunrise.  Best to avoid watering even at night during the hottest days of the year.  Most but not all California drought tolerant natives can handle light summer water once a month.  Try to simulate a light summer storm.  But don’t make the mistake of increasing watering in early fall.  Best to just wait for the rains.Also be careful about plants growing up around the sprinkler heads and blocking the spray.  The plants that the water hits first will almost always get too much water.  Finally, make sure the plants you are watering can tolerate a little summer water by checking the Calscape.org plant pages.  Most riparian California natives won’t have a problem with overhead sprinklers, but they’re risky for most drought tolerant plants.
  • Hose Watering
    Light hose watering is a fairly safe way to give your plants a little extra moisture during the summer.  Just dust off the leaves with a fine spray every month or so during cooler stretches.  But make sure you don’t put a significant amount of water right on the root ball.  If your plant clearly needs a little extra water, best to water indirectly by spraying the soil a few feet away from the root ball.

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