Avocado trees are an evergreen fruit tree native to Mexico and Central America. With the perfect combination of warmth and humidity, these trees can grow vigorously, usually reaching heights of up to 30 feet within just a few years. A major factor in an avocado tree’s healthy and accelerated growth is its root system. As long as conditions are ideal, avocado tree roots can spread up to 4 times their canopy width in the soil, while they have been known to reach distances of up to 20 feet.
For avocado tree owners, understanding the root system of the tree is important for providing the best possible growing environment. As long as the roots have space to spread out, an avocado tree can really take off, while controlling the root system will help prevent any infrastructural damage or other consequences.
Despite being well equipped to access nutrients and water, avocado tree roots often grow quite shallow in the soil, usually no more than 8-10 inches deep. While the roots do manage to penetrate very hard soils, the majority of their growth is done in the first few inches from the surface. Consequently, avocado tree owners should be aware of how close the roots are getting to more fragile elements, such as underground wells and septic tanks, as well as other structures such as foundations and driveways.
“Avocado tree roots are very strong, but we want to make sure people are aware of how quickly they can reach areas such as pipelines,” says Watkin Collins, a self-employed avocado tree care expert. “It can be easy to think that these trees don’t spread out too much, but they do. So, education and awareness are essential in order to maximize the advantages of these trees while minimizing the potential damage they can cause.”
Avocado trees are often considered a pest due to their high rate of growth and their ability to invade certain areas that may not be fit for planting. However, there are certainly methods of avoiding any infrastructural damage or nuisance problems when planting an avocado tree.
For example, making sure that the roots have plenty of space to spread out, by either planting trees a certain distance from any structures, or by pruning the roots regularly, can help ensure better growth and reduce damage. Furthermore, simply understanding the root system of the tree and how much room it needs to stay healthy can help owners keep a better eye on the tree’s growth.
Despite their vigorous growth, avocado tree roots can be managed with proper care, allowing for a healthy and strong growth. By following the advice of experts and understanding the tree’s root system, any perceived problems can be minimized and the trees can produce copious amounts of avocado fruits.
Soil Preparation
Since avocado tree roots are known to be rather shallow, it is essential to properly prepare the soil when planting the tree. The soil should be loosened up several inches down and any extra rocks or debris removed. Additionally, adding three to four inches of mulch around the tree can help keep the soil nourished and at ideal temperatures. Mulch also helps control weeds and pests, while encouraging the growth of beneficial soil microorganisms, leading to a healthy avocado tree root system.
Additionally, watering the soil regularly and deeply, preferably with two to four inches of water per week, can also help keep the tree healthy. Deep waterings allow for the tree roots to access moisture that is further underground and not just in the surface layers of the soil.
“The importance of soil preparation and regular watering cannot be understated when growing an avocado tree,” comments Collins. “Avocado trees need to be well taken care of in order for the roots to reach their full potential. If people are able to provide the right environment, their tree will be able to take off.
Fertilizer
Applying the right fertilizers can also help maximize an avocado tree root system’s growth. The right soil mix should contain approximately 10-10-10 fertilizer with micro-nutrients to give the avocado tree the necessary kick it needs to start growing. When applying the fertilizer, it is always advisable to go with a light scattering first, as too much fertilizer can potentially burn the roots, hindering the tree’s growth.
Additionally, using a good cover fertilizer, such as an 8-2-12 blend, can also help the tree sustain its growth. Cover fertilizers mimic natural compost, providing the tree with essential macro-nutrients like nitrogen, potassium, and phosphates, while slow-release formulas also help conserve the fertilizer over time.
“By using the right mix of fertilizers, an avocado tree root system can really take off and grow at an accelerated rate,” notes Collins. “It’s essential to be aware of the tree’s needs in order to ensure healthy roots and optimal growth, as that’s how people can maximize their yields.”
Root Pruning
If for any reason an avocado tree owner wants to control the tree’s remarkable growth, then pruning the roots can help. Root pruning is usually done with a pickax or any other suitable gardening tool. It is a fairly straightforward process which simply involves digging up the roots to about 8 inches deep and cutting away any longer roots that may become too uncomfortable or problematic.
However, it is important to keep in mind that pruning the roots may offer some advantages, such as controlling the tree’s growth and maintaining a better root-soil interaction, but it may also lead to some negative effects. For example, by cutting away certain roots, the tree may be put under more stress and it can also lead to nutrient deficiencies.
Therefore, it is always important to consult with experts when considering root pruning. That way, the pruning can be done in a way that helps the tree’s health. “Root pruning can be a difficult process and it should only be done when absolutely necessary, for example if it’s necessary to control the tree’s growth,” highlights Collins.
Roots During Drought
Since avocado tree roots are not very deep and are known to stay close to the surface, the tree can suffer if conditions become too dry. When soil dries out, it can become impenetrable for avocado tree roots, depriving them of essential nutrients and leaving the tree vulnerable to a variety of problems, from stunted growth to even death.
In these cases, it is important to keep the soil moist and, if possible, apply some compost around the tree to keep the soil cool and full of essential nutrients. For added protection, slow-release fertilizers and mulch should be added around the tree, as these elements can help provide the necessary protection when the environment is particularly arid.
Root Injuries
Root injuries on an avocado tree, while relatively rare, can nonetheless occur if certain conditions are not met. The most frequent root injuries are usually caused by the tree’s natural environment, be it during colder temperatures, being too near other trees, or being in an extremely dry environment. Other causes of root injury, such as infestations, can also occur in extreme cases.
If an avocado tree is indeed suffering from a root injury, the best solution is usually to introduce beneficial soil organisms to the tree’s environment. Introducing beneficial bacteria and fungi can help improve the overall health of the tree’s root system, as well as provide much needed protection against diseases, like root rot. Additionally, adding slow-release fertilizers can also help stop root injuries, as these provide essential nutrients over a longer period of time.
Soil Tests
Finally, periodic soil tests can help avocado tree owners keep better track of their tree’s health. A soil test can help identify any present problems and assess the soil’s nutrient levels which, in turn, could help inform the owner of any alterations they may have to make in order to keep the tree healthy.
By regularly performing soil tests, avocado tree owners can quickly identify any issues with their tree’s root system. Early intervention can help them detect and solve any potential problems in time, avoiding any future issues such as loss of production or even death of the tree.
“At the end of the day, an avocado tree is much like a pet,” concludes Collins. “By keeping a close eye on the tree and understanding its needs, people can really extend the life expectancy and production of the tree. Learning how far avocado tree roots grow is just one step of this learning process and, with the right care, people can really get the most out of their avocado tree.”
