UC Nursery and Floriculture Alliance
University of California
UC Nursery and Floriculture Alliance

When to Water Your Plants

When to Water Your Plants

by Jim Borland   Master Gardener

Everybody knows that plants can die of thirst, but don't forget you can also send them to an early grave by overwatering.  When we overwater, the soil becomes saturated and forces out vital oxygen, and we literally drown our plants.  So then how do we know when to water our plants? Here are some simple and useful methods that should help.

First thing to do is make a close observation of your landscape plants. A plant's stress symptoms which indicate it is too dry include wilting or folded leaves, dull or gray-green foliage, leaf drop, and new leaves smaller than normal.  These symptoms often first appear during the hottest time of the day, but before you automatically add water, check the soil moisture first!

The soil can be checked by the "feel" test where you dig down 6 to 8 inches in your garden, grab a handful of soil from that depth and squeeze it in your hand.  Moist soil will feel very cool to the touch. Both the tactile sensation and your analysis will vary for different soil types, but we can summarize by considering two broad categories: sandy loam and clay soil.  Sandy loam has poor moisture retention characteristics, so if you squeeze that soil and have some moisture on your hand, and if the dirt forms a weak ball, there is a good amount of moisture available for your plants.  Clay soil, on the other hand, is excellent at retaining moisture so it will form a tight ball and feel slick when there is an adequate amount of moisture present.  

You can also purchase small, portable soil moisture meters for
determining when to water, which cost pennies and are available at local garden centers.  There's new technology in irrigation controllers, referred to as "Smart" controllers which use current weather conditions being delivered from nearby weather stations and adjust automatically.  They also have the capability of having underground probes buried at root depth, to signal the controller to begin an irrigation cycle.  This is not only helpful in giving your plants the optimum water, but helps to conserve water during the rainy season.

Determining whether a plant needs water is always a judgment call.  With practice and good observation skills you can have a healthy, properly watered garden.
Posted on Thursday, May 3, 2012 at 6:13 PM
  • Author: Jim Borland

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