Great news! The rainy season is finally here!

Trees also rejoice in the rain after long, dry summers. But, how does rain effect tree roots? Can there be too much rain? Or, what if it doesn't rain enough? Read on to find out!


How does rain effect tree roots?

Why roots, you ask? Well, roots are often the "root" of the problem. The interaction between roots and water, or lack of, explains a lot about tree health.

During dry spells, roots slow down their growth, or even die back.

After heavy rain storms, a few things happen:

  • Waterlogged soils promote root rot and cut off oxygen supplies. Yes, roots need to "breathe"!
  • Soils become wet and less stable.
  • Lower soil stability + weak roots + heavy canopy = tree failure!

This is why tree failures are so common after the season's first rain storms! Maintain proper irrigation during dry spells and monitor before the rainy season to prevent tree failures.


How much rain is good?

We know that trees need water. But, how much rainfall is considered enough? The answer - it depends! Just like the rest of nature, there is no clear cut answer.

Water needs depend on tree type and size, with water-loving species and mature trees needing more water. Obviously. Furthermore, the amount of water absorbed during rainfall varies with soil type. Most tree roots are in the upper 2 ft of the soil. To saturate soil down to 2 ft, you'll need:

Amount of Rainfall Trees Need

Soil Type                              Sand               Loam              Clay
Amount of Rainfall        2 inches          3-4 inches       5 inches

Mature trees need a good soaking 2 ft deep into the soil about 1-2 times a month, depending on how warm it is. So keep an eye on the weather and weather reports. Also consider the tree's location. Is it in turf, under mulch, or surrounded by asphalt? Location will effect how much rainwater the tree can access.

There isn't enough rain. What can I do?

Sometimes, Mother Nature just isn't on your side, but that doesn't make you a loser! Here's how you can still have healthy trees and show everyone who's boss!


Mulch is so easy and so cheap! But it acts as a perfect water-retention blanket. It also provides nutrients, protects roots, and suppresses weeds.

Climate-Wise Tree Planting

Trees grow for a long time, so think ahead. If your local climate is projected to be warmer and drier, start planting trees adapted to those conditions. For example, if you live in a colder city that's projected to become as warm as San Diego in 10-20 yrs, find out what trees are thriving in San Diego. Chances are, they're survive and thrive in your area when it warms up!

Want more info? Check out the Space-for-Time tree selection strategy, created by the incredibly smart Igor Lacan, University of California Cooperative Extension Advisor.

Supplemental Watering

When nature fails, provide a little TLC yourself. If you don't have irrigation installed, use a soaker hose or our Deep Watering Treatment.

  • Soaker Hose: Place a hose under your tree on low flow overnight. Do this once every 2-3 weeks in dry months.
  • Deep Watering Treatment: We use a special cocktail of water, biochar, microbes, and soil amendments to boost soil moisture and root health.