The Water Test

The most common problem I hear about here in San Diego is watering requirements. The weather changes often and plants suffer because we always wonder how much is enough and how much is overwatering!

Here's a simple guide that hopefully you will find useful.

To begin not all plants want the same amount of water, some plants are much more demanding in their water needs. Some plants barely want any water. The way to find this information is rather simple: just Google the name of the plant and search for it's origin in the world. If a plant is from the tropical rainforest or from the high deserts you already have answered your question.

Now that you know where your favorite plant is from you can estimate how much water it is used to by the natural rainfall, how much does it rain in the rainforests of Brazil? How much does it rain in Anza Borrego Desert? These answers will get you very close to knowing exactly how much water your favorite plant wants.

So knowing how much water the plant wants is just the beginning! What about when you forget when was the last time you watered? In comes the water test! An easy way to tell when you watered last, taking into account the current weather conditions.

Often the dirt looks dry on the surface, and water retention is higher the deeper you dig down. Push your finger down into the earth one inch, is there any moisture you can feel with your finger? Look at the indentation you made by doing this. Is the earth darker or does it appear to have more moisture? The water test depends on different factors such as: are you testing native soil in the full sun, or is this potting soil in a shaded area?

Of course evaporation happens faster in the open sun, and of course shade will keep the soil wetter longer. Native San Diego soils hold water much longer and are very dense and heavy due to high clay content. They are practically devoid of organic materials in many places here. We usually amend our garden soils with different materials that change water retention and drainage issues.

Testing the water in your soils an inch down repeatedly will give you an idea of how much moisture will regularly be present after watering one day ago, one week ago, and etc.

When you put the information together: how much water does your favorite plant want and testing the soil at one inch to see moisture present, you should be able to more coherently understand what the plant wants. You will also have dirty hands! For more good information visit the Master Gardeners of San Diego.