Watering 101

Flowers, shrubs, trees and lawns

Basic rule of thumb – plants require 1” of water per week. This includes annuals, new and established perennials, new shrubs and new trees.

A rain gauge or an empty tuna can placed near the plantings is a simple tool to help you determine how much water an area gets in a week from either rain or irrigation.  This way, no matter what form of watering you choose, whether it’s from a sprinkler, a hose or Mather Nature herself, you can be assured that your plantings have received that crucial inch.

Established trees and shrubs can get by with less water as their roots have “rooted in” deeply.  During extended periods of drought it is good practice to water your trees and shrubs.  It has taken them some time to grow to their current size and their loss will greatly impact your landscape and be expensive to remove and replace.

Drought tolerant perennials, once established, can also get by with less water.  However, they cannot live on no water at all.

Traditionally, July in Chicago is a dry time of year.  We don’t get much rain and the sun is high in the sky and shining most days.  This causes water to evaporate from the soil at a higher rate than earlier or later in the season.  Winds will increase this rate of evaporation .  Plants in a hot spot will lose additional water from the soil and their leaves.  Examples of these hot spots are near paving, buildings and on hills, slopes or berms.  Paying attention to your plantings will help you to assess if and when additional water is required.

  • Sometimes the plants can tell you if they need water.  If they start drooping, water.
  • lmuch evaporation.
  • The best way to tell if water is needed is by sticking either your finger ora stick of some kind one inch into the ground.  Soil should be dry and you should not be able to form a ball by compressing it in your hand.  Remember, oxygen exchange to the root system is as vital as the water!  Be sure to move an mulch away so you are actually getting to the soil.  After watering, re-check using the same method to see if you’ve watered enough.
  • It is best to water DEEPLY to encourage the roots to go deep.  Infrequent, deep watering is better than frequent, shallow watering.  Shallow roots get burned and cannot get enough water during a drought.


Turf requires 1” of water every thirty days.  The lawn will go into dormancy when there is less supplied.  The turf grass plant responds with a series of plant defenses.  The visible steps progress from a purplish wilting to a straw like appearance.  Keep in mind, going dormant is the turf’s natural defense system.  Those defenses protect the plant through a typical period of drought until the conditions change in favor of eventual recovery.