Eucalyptus trees naturally grow in some of the most arid regions of the world. This being said, the plants do require moisture, especially for the first two years of establishment. The roots grow slowly and gradually spread out around the trunk zone. Knowing when to water a eucalyptus tree is only part of the equation. The rate and diameter needed to reach the roots is also important knowledge. Eucalyptus tree watering needs will also change depending upon the season and your soil type. Here are a few guidelines on watering eucalyptus trees for optimum health and water conservation.
Rates for Eucalyptus Tree Watering
Irrigating eucalyptus trees is most important in the first couple of years, but even established trees need a regular watering schedule. Eucalyptus are evergreen trees and do not recover well from wilting. Deciduous trees have the option to drop their leaves to conserve moisture and make recovery more possible, but evergreens keep their leaves. The leaves draw much of the moisture and evaporation, which drains the tree of water.
Overwatering eucalyptus trees is a possible result of over vigilance. Young trees only require 1 to 2 gallons (3-6 L.) of water during the dry months. This can occur once per week in most soils but may require irrigating daily in sandy soils in full sun.
The actual rate once the tree has grown will vary due to soil porosity and site but, on average, the soil should be moist 3 feet (1 m.) down into the earth. Young trees should be moist 2 feet (61 cm.) down. It is important to keep expanding the watering zone out from the trunk as the root system spreads.
Mature trees should be watered out from the canopy to capture the lateral root tips where most of the nutrients and moisture are harvested.
When to Water a Eucalyptus Tree
Early morning or evening is the best time for watering eucalyptus trees. This promotes maximum usage of water, and the cooler temperatures reduce evaporation. Water eucalyptus deeply rather than in shallow sprinkles. This helps leach soil of salt buildup and allows water to reach the deeper roots.
A slow application rate is preferable because it allows dry soil to soften up and increases percolation. When irrigating eucalyptus trees with a drip system, it should be expanded over time as the tree grows. Similarly, with an irrigation system, the emitters need to be moved out over the root zone.
Overall, in hot climates, it is best to water new trees at least once per week and established trees every 7 to 21 days. The more frequent time recommendation is for trees in sandy soil.
Types of Eucalyptus and Their Water Needs
Overwatering eucalyptus trees is also a danger. It might be helpful to know the water needs of many common species, as these vary. For instance, Eucalyptus preissiana has the lowest water needs of all the species and Eucalyptus deglupta requires regular moderate moisture.
The following are considered low moisture plants:
- Eucalyptus microtheca
- Eucalyptus pulverulenta
- Eucalyptus erythrocorys
- Eucalyptus ficifolia
- Eucalyptus forrestiana
- Eucalyptus lehmannii
- Eucalyptus maculate
- Eucalyptus nicholii
- Eucalyptus nutans
- Eucalyptus platypus
- Eucalyptus polyanthemos
- Eucalyptus sideroxylon
- Eucalyptus torquata
- Eucalyptus viminalis
- Eucalyptus qunnii
If in doubt about your tree variety, monitor water needs by digging into the soil and checking for moisture at least 2 feet (61 cm.) down in the dry season and watch the plant’s leaves for signs of wilting or stress.