My parents have a fig tree in their backyard and they were wondering if it would be a good idea to plant another fig tree closer to the house. To help them out, I did some research. Here’s what I found about the invasiveness of fig roots.
Fig trees have some of the most invasive roots out of all of the fruit trees. If left unchecked, a fig tree’s roots can cause damage to sidewalks, driveways, and walls. For best results, plant the fig tree at least 25-50 feet from structures or grow the tree in a pot or root barrier.
So, while fig tree roots are generally invasive, just how invasive are they, and what are some ways we can control them? Let’s take a closer look.
How Long Do Fig Tree Roots Grow?
Generally, fig tree roots grow up to 25 feet long, or about the length of the tree’s drip line. On the other hand, dwarf fig trees have roots about 15 feet long. Because of this, it’s best to keep fig trees at least 25 feet from structures such as fences, walls, and foundations to avoid damage.
Fig tree roots are responsible for gathering primary resources from the surrounding environment such as:
Ideally, the best soil for fig trees is one that’s loose, rich, moist, and slightly acidic (pH of 5.5-6.5). Soil that meets all three of these qualities will promote the best root growth.
The reason why fig trees grow such long roots is that the topsoil is where much of the nutrients and water is located. Additionally, by spreading their roots out, fig trees anchor themselves from the wind and pressing herbivores.
On the other hand, the growth of fig tree roots is limited by:
- Cold weather
- Compacted soil
- Lack of water or nutrients
Compacted soil is common in suburban areas or construction sites and will give fig trees a hard time growing their roots.
The same is true with heavy clay soils. The compact nature of clay soil not only makes it difficult for the tree’s roots to grow but creates poor drainage and makes nutrients in the soil unavailable (via its alkalinity).
If you’d like to learn more about planting or amending clay soil, check out my recent post: Can Fruit Trees Grow in Clay Soil (& How To Plant Them)?.
So, fig tree roots can grow up to 25 feet long, but how deep do they grow, and will they damage pipes?
How Deep Do Fig Tree Roots Grow?
Fig trees have shallow roots, with 90% of the roots found in the first 2′ of soil. Other, deeper roots can reach up to 3′ deep. While many factors contribute to the depth of fig tree roots, the main factors are water, nutrients, and space. Fig trees are unlikely to damage pipes, but should be placed away to be safe.
Most roots are found close to the surface, with 90% or more of all roots located in the upper 60cm [24 inches].Martin Dobson, Arboricultural Advisory and Information Service
Fig tree roots grow to different depths depending on environmental conditions such as:
- Soil packing and quality
- Water content
Generally, fig trees have two types of roots: shallow and deep. While the tree’s shallow roots are effective at growing through the topsoil and gathering fresher nutrients, the deeper roots specialize in accessing deeper water tables (along with stored nutrients). They commonly reach 2-3 feet deep.
Dwarf rootstocks feature an effective feeding root depth of 1-2’, while full-size trees probe 2-3’ deep.The University of California, Santa Cruz, Center for Agroecology & Sustainable Food Systems
The deepest root is the taproot, which has the main function of establishing a foundation for the rest of the roots. The taproot is one of the first roots to grow and can access the nutrient and water potency of the soil. It commonly grows to a depth of around 3 feet. If the taproot is damaged, the rest of the tree will likely become stunted.
Since fig tree roots are more shallow than other fruiting trees and can grow fairly deep and long, some gardeners are concerned that they’ll damage property.
Can Fig Trees Damage Property or Structures?
The roots of fig trees are rarely the cause of foundation damage but can displace walls or fences as they grow. This is due to the shallow root systems that spread horizontally just under the surface. Fig tree root systems are more likely to destabilize the ground than directly cause any damage.
While unlikely, fig tree roots can cause potential damage to:
- Fire Hydrants
Also, the most invasive fig tree varieties include:
- Brown Turkey
- Florida Strangler Fig
Even though the above fig varieties have the most aggressive growth, other varieties are still capable of possible damage.
However, fig tree roots are not as strong as other, larger trees, such as oaks. For this reason, fig trees are not likely to pose an issue compared to other trees.
The California Polytechnic State University lists fig trees with a low root damage potential (source).
The most likely scenario is the fig tree’s roots displacing a light fence or wall as the tree is growing.
In the book The Hidden Life of Trees, Peter Wohlleben busts the myth that a tree’s roots are attracted to water from water pipes. He shows that the more likely case why they’re attracted to the pipes is that they generally have looser ground, which allows for more air and space for root growth. The water is more of a bonus.
However, if there is water under the foundation, roots can dry out shrinkable clay soils. This indirectly causes damage by contributing to the depletion of soil moisture which can cause the foundation to recede into the ground. But this situation is uncommon and old age is a more likely culprit in foundation damage.
Still, it’s better to be safe than sorry. Because of this, plant fig trees away from structures if possible.
How Far Away Should You Plant Fig Trees From Structures?
As a general rule, fig trees should be planted at least 25 feet away from structures such as foundations and walls. This will avoid any potential damage from the tree’s roots or branches. It will also ensure that the plant has enough space to grow and find sufficient nutrients in the soil.
When you’re planting your fig tree, aim to keep it at least 25 feet away from structures, but no more than 50 feet away from the rest of your garden. This is because other plants, such as companion plants, can’t benefit fig trees when they’re out of range.
Simply put, it’s not likely that pollinators, such as bees, butterflies, and hummingbirds, will visit both the companion plants and the fig tree.
Speaking of companion plants, if you’re interested in seeing the 10 best companion plants for fig trees, check out my recent post: The Top 10 Companion Plants for Figs.
Planting your fig tree away from structures is the best way you can prevent any potential damage. However, what are some other methods of control?
How To Control Fig Tree Roots
The best way to control the growth of a fig tree’s roots is with a root barrier. You can also prune the roots or keep the tree in a raised bed or pot. While all of these options are sufficient in managing a fig tree’s roots, pruning can stunt the tree and is more upkeep than simply planting in a root barrier or pot.
Generally, the best ways to control a fig tree’s roots are with the following four methods:
- Root Barrier
- Root Pruning
- Raised Beds
Root barriers are used to redirect the tree’s roots deeper into the soil and away from fences or foundations. This physical blocker protects your property as well as the fig tree. On the other hand, planting the fig tree in a pot will naturally bind its roots.
Keep in mind that fig trees grow an average of 36 inches per year, so they can quickly outgrow their pot. Because of this, it’s best to provide potted fig trees with a new, larger container every 3-5 years. If you feel comfortable, you can also prune the roots during this time to slow the tree’s growth.
If you’d like to get an idea of a good root barrier you can use for your fig tree, this root barrier on Amazon is a popular choice.