Climate change, drought, heat…what are your trees drinking from 5:00pm to 7:00pm…or any time of the day or night?  If they’re like trees in Santa Barbara and most of Southern California, they may be parched.  Our region is about 8” short of rainfall this year, 50% of the normal 16”-18” annual rainfall.

3443066198_98b71f0100Water is required for all physiological processes within a tree.  Reduced water in the soil can cause stress, and lead to decline or death.  Stressed trees are highly susceptible to pests and diseases, some of which are fatal.  Even drought tolerant native plants may be stressed during these tough times and benefit from occasional deep irrigation.  No doubt, most trees need a good deep drink.

Here’s a calculation that may surprise you.  Every 1” of rainfall  provides 0.60 gallons of water per square foot of soil (12” by 12”).  One eighth acre, the standard size of a small residential lot in Santa Barbara, is 5,445 square feet, including the house (⅛ of 43,560 sq.ft.=5445 sq.ft). Bottom line: 1” of rainfall per ⅛ acre equals 3,267 gallons of water on your landscape.  That means an 8″ shortage of rainfall in a year is a deficit of 26,136 gallons per 1/8 acre lot (⅛  acre x 43,560 square feet/acre x 0.60 gallons x 8” ). That’s what is missing from every small lot in my neighborhood.  To determine how much water your property receives per inch of rainfall, multiply the square footage by 0.60 gallons/square foot.  Some of this water is likely to run off into adjacent gutters or storm drains, depending on your soil type, structure, and the rate that rain falls.

Are you familiar with your soil type?  Understanding this helps determine how to irrigate trees.

  • Course textured sandy soil drains well, has an abundance of oxygen available for roots, but doesn’t hold water or minerals for any significant amount of time.  With adequate water and fertilizer, roots can grow deep with less of a spread.  Frequent irrigations for short periods of time can benefit plants in this environment.
  • Dense textured clay soils (more typical here in many local areas) can hold a significant amount of water and minerals.  Clay soils need less frequent irrigation but for longer time-periods and at a very slow rate.  Drip emitters distribute water by droplets that allows for the infiltration into these dense soils with reduced or no runoff.  Root growth tends to be shallower but more spreading.
  • Loam soils are a mixture of clay, sand, and silt.  They hold water and minerals, have an abundance of oxygen, and drain well (provided they have not been compacted).  Loamy soils are often found in natural areas void of construction.  Roots can grow deep and spread wide.adjusting_water_to_match_your_soil2-9SoilTypeFigure2

Many products on the market can help your trees.  But here’s a link to a great tool you can build for about $60.  My deep water jet uses hose pressure and a minimal amount of muscle to penetrate compacted soil and and get water to the root system.IMG_4383

For the link to my instructions, click here.  Then take a trip to your local hardware center with this plan and put together a great tool that can energize your trees and shrubs.  Make it a happy hour for your trees.

How can I help you with your trees?

Treemendously yours,

Bill Spiewak