As most tree services or tree care businesses would agree, watering your trees cannot be uniform across all seasons. With Australia experiencing the sunniest days across the year, your landscape trees are largely dependent on you for water. Given the present situation across most parts of Australia, freshwater is scarce and there is a need to secure the available freshwater. Add to this, the fact that most of the 3 million square miles of Australia is dry and hot. The average rainfall in Australia is already dipping and predictions related to climate change are suggesting a further drop.
With precious little that homeowners can do to alter Australian climate or influence the pattern of rainfall, your landscape trees cannot survive without water. That also brings into focus the measures you can adopt while your tree planting exercise is on. You should understand the types of trees that can thrive on minimum water and those that wither away quickly when adequate water is not available. There are many tree services and tree care businesses across Australia and you can contact them for appropriate guidance when needed.
Soil type, weather, the season, age of the tree, the species are among the factors that would determine the water needs of each type of tree. As a thumb rule, young trees and newly planted trees need watering at more frequent intervals compared to well established and older trees. However, when your region is experiencing extreme drought supplemental watering can benefit all plants. Your goal during drought conditions should be to provide supplemental irrigation to help maximize the growth of young trees while keeping the established and older trees healthy. However, you should also bear in mind that excessive watering can make your trees irrigation dependent than being resilient to survive with water from nature. But, given the Australian arid climate, excessive watering may not be a problem since the availability of water would be scarce. During several months following tree selection and planting most tree roots remain within their original root balls.
Watering trees planted newly
For several months post-planting, most roots of a tree still remain within its original root ball, while some roots begin growing beyond that area. The root ball and the soil surrounding it should remain evenly moist so that the roots can grow healthy. The watering zone should be expanded after some months so that the entire area under its canopy is covered. For your newly planted tree to become established, it can take up to two growing seasons or more when the roots will also venture into the soil beyond its planting hole. It is also crucial that supplemental moisture is also provided during the early years of the tree, particularly when natural soaking is not provided by Nature. New trees may also need three to four watering per week when the weather is particularly dry and hot so that the root fall can survive the heat. Once you notice that the tree is well established, apply water in wider bands around outer reaches of the canopy of the tree, which is also known as drip line.
Watering for established trees
There is a misconception that the roots of the tree mirror the image of the canopy aboveground. In fact, the roots of an established tree generally extend well beyond its canopy edge, or the drip line. While some anchor roots might go deep into the soil, with most trees the roots can be seen concentrated in the 12” to 18” depth of the soil. When you are watering trees that are already established, you should provide deep and soaking irrigation to all the area beneath the canopy of the tree extending to several feet away from the drip line. Ideally, you should be moistening the soil up to about 10” depth every time you are watering. But, you should also take care not to apply water to areas falling directly around the tree trunk to keep safe from rot.
When should you be watering?
The easiest means of checking moisture level in the soil is to use a long screwdriver (8” or more) and poke into the soil. If the screwdriver can pass without any difficulty in the soil, there is adequate moisture around the tree. When the screwdriver cannot get beyond 6” with ease then it is time to water. This technique is very useful in loam and clay soils.
Methods of applying water
The easiest way to apply water over large expanses is using overhead sprinklers. However, they are not very efficient since you could lose about 50% of the water because of evaporation. This can also be a huge challenge in most Australian regions because of the scarcity of water. Watering methods that apply the water at a slow pace straight at the level of the soil is better suited for trees. Several hours may be consumed in properly watering just one mature tree. Soaker hoses, on the other hand, are reckoned as an efficient alternative for watering trees since they are porous and release water at a slow and steady pace. You can lay the soaker hose encircling the tree like a spiral and run it for about an hour. You can use the screwdriver test to know when you can stop the water. You can also enhance the efficiency and life of the soaker hose by adding a pressure regulator. Another add-on feature is bubblers attached to the end of the hoses to reduce the velocity of water so that you can prevent runoff and allow more soaking. However, the bubbler may need to physically move around since the soaking is done on only one spot at one time. You should also avoid watering when the sun is blazing at the hottest.
Watering techniques for extremely hot and desert-like conditions
In the first place, it could be very challenging to grow trees with any degree of success if you experience hot to very hot conditions for 10 or more months across the year. Even reclaimed water may be used for other applications and watering trees may be the last priority. But, if you can successfully grow a tree, then you should be able to soak the soil around the tree to a minimum depth of 3’. With deep irrigation, the roots tend to grow deeper opposed to shallow roots from frequent and light watering.
Minimizing stress for the tree during drought
When drought conditions prevail, you can take several measures to minimize the stress for your trees including:-
- Do not dig around the trees so the roots remain undisturbed
- While you can remove dead, broken, diseased or insect-infested branches, never prune during these days
- Watch out for diseases and pests since trees suffering drought-stress can be more vulnerable to attacks
- Avoid the use of fertilizer high in nitrogen usually used for your lawn under the trees and keep the weed n feed products away since they can be harmful to the tree roots.
Final thoughts
Choosing between trees and the turf can be difficult. Trees constitute a bigger investment for posterity and it takes years or even decades for a new tree to grow into a mature tree
