I’ve been frequently asked this question in recent years since fig trees became a bit more popular. You can never be too careful with fruit trees and their roots. Luckily, some are less dangerous than others. Even within a certain species, there are such varieties that a question like this requires some knowledge and experience to answer correctly.
I’m not an agronomist specializing in fig trees, but me and my family have generations of experience passed on down the family line about cultivating many fig tree subspecies. Based on that, I will try to explain how invasive fig tree roots are and how you can restrict them, even for the benefit of the tree.
Are fig trees and roots invasive?
Yes, fig trees and roots of certain species are invasive. Bigger fig tree species like the Brown Turkey Fig tree have more invasive roots that spread on the large area while species like Celeste or Malta Fig tree tend to have less aggressive roots covering a smaller area.
How Deep Are Fig Tree Roots?
Most fig tree species, like other species from the Ficus genus, spread their roots wide and shallow. You will find roots between 1 and 5 feet(0.5-1.5m) deep. However, being a member of the Ficus genus means their roots will follow any source of water and fertility. Meaning, if there is an underground source of water and fertilizer, especially leaky sewage pipes, the roots can grow as deep as 20 feet (6m).
That counts for cultivated fig trees. However, if the trees are left to grow wild, in perfect conditions, the roots can become enormous.
Will Fig Tree Roots Damage the Foundations of My House?
The whole reason for me writing this article is that fig trees are known for damaging pipework and house foundations. As soon as there are questions about this, means there is something to it. Since I never had an issue like this, I asked older members of my family and several people that I know have large fig trees. The answers I got only confirmed my own thoughts about this matter.
The question about fig tree roots being damaging to house foundations isn’t a simple yes or no answer. It depends on many different things which I will try to explain in detail. Most of it depends on the correlation between positioning, climate, soil conditions, and how well the tree is cared for in the first few years.
Are Fig Tree Roots Strong?
Unlike what most people will tell you, fig tree roots are not actually that strong. Most fruit trees have way stronger roots than figs but they don’t spread that aggressively. The word I would use to describe fig tree roots is greedy. In a similar way that many biologists describe genes as greedy and selfish.
Fig tree roots are not the strongest but it’s like they have their own stubborn will. After the first few years they just refuse to bend around objects and in time go right through them.
How Close to a House Can You Plant a Fig Tree?
On average, I would recommend planting a fig tree from 10 feet (3m) all the way up to the far end of your yard. The reason why it’s such a wide area where it can flourish is that different climates affect roots differently.
In colder or humid climates, fig tree roots are smaller and weaker because they don’t need to go far to get everything they for the tree to grow. In colder climates especially, fig trees don’t even become that large because winters cripple their growth. In conditions like these fig trees can be planted close to a house without fear of their roots become too invasive. They even benefit by being close to the southern wall of a house because they can absorb more heat that way.
In areas with warm and dry climates, I always suggest planting fig trees at or near the corner of your backyard. Since their roots will aggressively look for water in these situations, it’s best to give them as much room to grow as possible.
There are methods to restrict fig tree roots from growing towards your neighbor’s backyard or even towards your own house’s foundations, and I will explain them in detail later on.
Now that I’ve explained few things about fig tree roots in different situations it’s time to give a definitive answer to the previous question.
Will Fig Tree Roots Damage the Foundations of My House?
Fig tree roots growing in dry warm areas will damage the foundations of your house due to being aggressively invasive, however, it can be prevented. In colder and more humid areas, fig tree roots don’t grow as big and strong and rarely cause any damage to house foundations.
How To Contain Fig Tree Roots?
There are several ways to prevent fig tree roots from growing uncontrollably. Each of these relies upon an area in which you want to plant them, and how much care will you be able to provide them through the years.
Pruning Fig Tree Roots
Root pruning is usually done before the tree is planted in the ground. While it’s being grown in a pot you can take time to prune its roots to about two-thirds of their length several times to force the fig tree to develop lots of thinner, weaker roots that won’t become invasive later on. The tree can still grow large because even though roots are thinner and weaker, there are a lot more than of them than it would’ve been without pruning.
Roots can be cut when the tree is planted in-ground as well, even when it becomes quite large. For example, I prefer cutting roots that go toward my house from time to time, just to be safe. It won’t damage the tree because not all the roots are being cut. On the side where you decide to cut roots, the same thing happens as with pruning. However, the older the tree is, the less effective this method becomes.
Pruning Fig Trees
I found that pruning fig trees correctly during their first three to four years is also an effective method of controlling their roots. Pruning the tree, by removing bigger branches to keep the shape proportional on each side, slows down root growth. My guess on why fig trees behave this way is because the tree doesn’t require as much water and energy when big branches are removed from it.
I find it effective to prune fig trees in late winter, just before it starts growing again. That way, the places where branches get cut aren’t exposed to winter conditions as much which makes rotting easy to prevent.
Restricting Fig Tree Roots
Another method of controlling fig tree roots that I used many times is literally restricting them from growing in a certain direction.
Some people plant a fig tree in a pot by placing it all together into the ground. That method is great if you want to keep your fig tree smaller for many years. I never liked recommending this method to other people because it requires constant care while most people choose fig trees specifically because they require less care than most fruits. Roots being restricted inside a pot means you need to provide everything the fig tree needs countering, the biggest biological advantage of fig trees, being able to spread roots until they find everything they require.
My preference is blocking access to three out of four sides by placing a “U” shaped wall inside the hole before I will plant a fig tree. This will force roots to spread in the direction you want while allowing the tree to grow large. That is the way I always protected the foundations of my house.
Why both of these methods work is because restricting fig tree roots is crucial within the first few years. When an older fig tree encounters an obstacle it forces its way through because roots are already strong and “stubborn”. Younger fig trees tend to adapt to obstacles rather than forcing their way through.