Orange tree roots are not invasive but they can spread a long way on a full grown tree. An orange tree that is well established in good quality soil can grow a tap root as deep as 12 feet and roots as wide as 20 feet. An orange tree’s root system will match closely to the size of the leaf canopy when the tree is younger but can grow wider as the tree matures.
This article will explore all you need to know about orange tree root systems, how big they grow and what you can do to support a healthy tree.
Facts about orange tree roots
Here are my top tips about orange tree roots, including invasiveness, size and how to grow a healthy orange tree.
Invasiveness of orange tree roots
Orange trees do not have invasive roots and they will not try to break through pipes or concrete. While they are not invasive like a fig tree they can still cover a large area and can fill the top 2 feet of soil quickly with roots.
It is best not to plant orange trees near houses, foundations or any concrete areas as this can limit the root system of the orange tree. These trees can grow large so the more space they are given, the better and larger they will grow.
You can also opt to keep your orange tree smaller by trimming the top branches regularly. This will help to keep the roots under control and the tree will not need such a large root system to support a smaller tree.
Most of the orange tree roots are in the top 2 feet of the soil
Orange trees, like most citrus will concentrate their smaller feeder roots in the top 2 feet of soil. These roots absorb most of the nutrients and moisture in the soil. The small feeder roots grow near the surface of the soil which means it is important not to disturb this area underneath the tree canopy.
Because roots grow close to the surface it is important to think carefully about what to plant near them. While you can avoid planting underneath them altogether you can also opt for ground covers that can be planted slightly further away. These can act like a living mulch without interfering with the roots.
Good soil will support deep roots
The key to a healthy orange tree root system is to plant it into good quality soil. Before an orange tree is planted in the ground it is important to make sure that the soil drains freely. The soil level can even be raised slightly to help with drainage.
Before planting any citrus trees including oranges I will mix through a bag of aged cow manure. This contains a range of nutrients, is high in carbon, organic material and works to lighten the soil.
I will also mix through compost and worm castings if I have them. These are fantastic additions to your soil. Worm castings can also be bought in bags now from garden centers and some hardware stores.
After the tree has been planted for at least a year, you can top dress the soil with compost or aged cow manure. Use a rake to move the mulch back and layer 2 inches of organic matter on the top of the soil. Cover this with mulch and water it in well.
For more on top dressing orange trees, check out my previous article here: How to top dress citrus trees | The Easy Way
Deep watering orange trees grows a strong root system
The best way to support a healthy, deep root system for orange trees is to water them deeply. Rather than a light water every day or two, a deep water once or twice per week is a better option for orange trees. Use a garden hose and water the orange tree at the base around the root system.
A tree that is watered deeply will grow a deep root system. The tree will reach down into the damp soil as time goes on. This will help to stabilize the tree, and make it better able to withstand windy or stormy conditions.
It is best to keep water off the leaves if possible as this will help to reduce the risk of mold and pest attack.
How deep orange tree roots grow
Orange trees can grow deep roots if they are older, watered deeply and have access to good quality soil. Long tap roots can reach from 8-12 feet but can stay shallower if they are limited by heavy soil, grown in a pot or raised garden bed.
I am growing an orange tree that is currently around 5-6 feet tall with a root system that is no deeper than 2 feet. The roots of a tree that only has access to shallow soil is more likely to send out a wider root system. I have found this and have even found orange tree roots beyond the tree canopy.
How far orange tree roots spread
Orange tree roots can spread beyond the tree canopy. Most of the roots will stay under the tree drip line but the more established the tree, the more likely it will be that the roots will spread deeper and wider.
Orange tree canopies can spread as far as 20 feet and dwarf orange trees tend to stay around 6-8 feet.
All orange trees can be kept smaller through trimming and their roots will mirror this.
While my orange tree roots have spread wider than the canopy I have still successfully grown plants next to it without damaging the tree. I have planted a lemon tree and some small flowering bushes nearby and the orange tree is still thriving.
The key to successfully growing orange trees in shallow soil is top dressing every year with compost and aged cow manure. I also add pelleted chicken manure to the tree over spring and again in fall. This helps to feed the tree, soil and microbes.
This added fertilizer will help to support an orange tree that has a smaller area to grow its roots. This means you can grow trees closer together and share the space with companion plants.
Take care of orange tree surface roots with mulch and water
Take care of your orange tree by protecting their surface roots with mulch. Mulch is important to keep the water in the soil for longer. This will help to feed worms and soil bacteria which will slowly break down the mulch over time. This will release nutrients to the plant and increase organic matter in the soil.
While there is often a short term decrease in nitrogen in the soil when the mulch is added, this is easily offset by the pelleted chicken manure to boost the nitrogen for your tree.
Mulch placed over the roots will also help to cushion the soil in case kids or dogs (or you) end up walking over the root system. This is sometimes necessary when you are harvesting oranges. In this case, mulch can protect the roots.
Are orange tree roots invasive? | Summary
Orange tree roots are not invasive and their spread is determined by how good the soil is, how old the tree is and how much water it gets. Roots can spread out further to find water if the deeper soil is poor quality. Orange trees that are watered deeply with good ground soil will grow a balanced, deep root system to support the plant.
Dwarf orange trees will stay smaller as a tree with smaller root systems but any tree can be kept small through trimming. I trim my orange tree at the beginning of spring and fall to keep it small and then I won’t prune again once the small oranges have appeared.
This will allow the orange tree to develop fruit while still keeping the tree small.
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