THE GREEN THUMB ALMANAC 

Knowing when and how much to water is as much an art as a science.  Learning the science of watering is relatively easy...it is the art of watering that is most difficult.  Why?  Because the art of watering involves experience and experience takes time.  This page is the most important page on this entire website.  If you master both the art and science of watering you will be able to grow anything!  Remember, improper watering is the #1 killer of plants!

The science of water involves how water behaves in different types of soil conditions.

• Water wants to stay together, this is called cohesion.  Water also follows the path of least resistance.  This can be observed when you try to water soil that has become too dry.  Dry potting soil, for instance, will actually repel water.  In a container this means that the dry soil will shrink and pull away from the sides of the pot.  Then, when water is applied, it will run off and down the sides of the pot and out of the drainage hole leaving the plants root ball dry.  In this instance you will have to double- or even triple-water the container before the soil is moist enough to absorb water.
• Another principle of water is called capillary action.  This is the movement of water upwards from the bottom of the pot.  So when you sit a dry pot in a saucer of water it sucks the water upwards.  This is a good thing if the plant needs water.  If the plant is already moist, however, it can be a negative by keeping the root ball saturated.  So if the soil stops absorbing water after an hour, empty the plant saucer of any remaining water.  Most plants do not like to sit in water for an extended period of time.

1.  Create a berm just outside of the planting hole that will retain water long enough to soak the root ball of the plant (often times the back fill soil will saturate much more quickly than the root ball itself, leaving the root ball relatively dry).
2.  Heavily water your tree or shrub prior to, immediately after, and the day after planting date.  This insures all voids between the root ball and ground will be filled.  Having too much air contacting the roots can stress plants.
3.  Maintain a watering schedule.  Water twice a week (three times a week in +95 degree weather) for the first month (when there is less than an inch of rain per week).  Ideally a 5 gallon bucket with a few holes poked in the bottom and sides should be sufficient for large trees and shrubs.  The slow release will allow for the water to soak in before it becomes runoff travelling away from the root ball.
4.  After the first month, 10 gallons (add 10 gallons per inch of diameter for trees greater than 2") once a week will percolate deeper into the soil, coaxing a deeper root system.  Smaller trees may require less amounts of water, but be sure the root ball is thoroughly saturated.  During excessively hot weather (95+), go ahead and water twice a week as the soil begins to dry out much more quickly.
5.  Don't neglect your plants during the winter!  Just because they drop their leaves doesn't mean they don't get thirsty.  During winter months, however, watering amounts should be reduced by half as long as the ground isn't frozen.  Shorter, cooler days make plants require less moisture.  Make sure the ground isn't frozen, and a mild temperature is forecasted for the next 2-3 days that won't freeze the ground deep enough to harm the roots.  Winter rules especially apply to evergreens.  Because evergreens maintain their leaves, they lose more water moisture than deciduous trees and shrubs.
6.  During the second and third growing seasons after planting, continue to water trees and shrubs every 10-14 days if it doesn't rain and soil moisture indicates the need to water.  As the root system of these plants extends during establishment, water in a wider ring around the plants, soaking the soil to a depth of 8 to 12 inches.
7.  Turf grass growing over the root system of young trees competes for moisture.  To reduce competition, maintain a grass-free area around the base of the young tree, extending to the drip line of the outer branches or beyond.
8.  An organic mulch around the base of young trees and shrubs is recommended to keep the soil moisture more uniform and to stabilize soil temperature.  Apply and maintain an organic mulch ring 2 to 3 inches deep around the base of the tree, covering the grass-free area.