A fig tree can grow in tree or bush shape, making it problematic for the tree to know if the tree trunk needs more strength. The strength comes from tree trunk thickness.
In ideal conditions, a fig tree could be left to grow on its own, and it would grow a perfectly thick and strong trunk. However, this happens only in warm climates. While in colder climates, we have no choice but to help it develop strength before it grows in size.
Leaving it to grow on its own is not optimal for fruiting even in warm climates. Therefore, we are stuck with restricting its growth with pruning, pinching, and so on, while at the same time wanting it to grow thick and strong.
The real question is how to make a fig tree thicker while growing the best fruit possible. These two things actually oppose each other.
Let’s see how we can make this work!
Staking a Fig Tree
The first mistake everyone does is staking a fig tree when unnecessary. Especially potted fig tree.
Assisting fig trees with stakes is necessary only at certain times and growth conditions, such as the first year of growth, if deciding to focus on side branches.
Other than that, stakes only retard the growth making a fig tree rely on it for strength and never develop its own.
Personally, I avoid staking fig trees unless absolutely necessary.
The first step of pruning is to know what shape you want your fig tree to have.
To be fair, pruning doesn’t need to be more than usual unless the situation requires it. As I mentioned before, fig trees grow thick trunks if conditions for their growth are above average. However, in colder and humid climates, fig trees tend to grow in length more than thickness.
Generally speaking, shortening a fig tree only makes it effectively stronger against some conditions due to how bending force is increased by length. If the conditions that want to bend the tree are not present, shortening the tree is counterproductive unless done for other reasons like fruiting.
Because staking is not an option, fig trees require length restriction in these conditions. By length, I mean pruning the top and length of side branches each year to give it time to thicken.
It would be difficult to give some specific rules about it, because the way the fig tree grows can differ a lot depending on the variety and many other factors.
The best advice I can give is to prune the tree’s top the same way as you would to increase sun absorption.
The main growth, which is an extension of the tree trunk, should be let to grow a bit each year and only then cut off. If you cut it off immediately, the trunk won’t thicken as much because it gives the tree a signal to ignore trunk development more than absolutely necessary to support side branches.
A perfect balance between the two will keep the tree from growing in height while making the trunk thicker at the same time.
To conclude what I just explained; In above-average climate conditions, you can let the tree grow tall, and it will strengthen the main growth and its trunk faster. In poor climate conditions, the tree will try to grow tall but ignore the trunk thickness, resulting in the fig tree breaking when exposed to strong winds.
Fig Tree Pinching
You can achieve the same thing by additionally pinching new growth each spring or early summer. Ideally, you want to let the fig tree extend new growth by about 6 inches before pinching the tip.
Six inches is just a general rule, and a more precise estimate would require seeing the tree in person and deciding where the growth needs to be kept longer or shorter.
Exposing a Fig Tree to Wind Regularly
Exposing a potted fig tree to wind will strengthen its trunk and even make it thicker and girthier.
It’s sometimes tricky to estimate if a fig tree is strong enough to survive a certain wind strength. If your estimation isn’t great, you are risking it breaking.
I broke a potted fig tree once this way, and I still regret it. However, it helped countless fig trees of mine grow strong.
Silica, or silicon dioxide, has proven very useful as a fertilizing additive for plants and trees. It’s completely natural and normally found in the ground. It strengthens the core cells of any plant, including stems and sapwood.
Adding it to a fig tree while young can ensure the trunk gets thick and strong to withstand a lot of pressure from the wind or tree size.
I used Silica Blast some years ago, and it worked great. I don’t always use it only because I know how to prune the tree perfectly for trunk size. However, it’s the perfect tree supplement for people with less experience.
Reasons Why a Fig Tree Refuses to Grow Thick
I already mentioned cold climates as the main reason fig trees tend to grow thin because they prioritize height over strength. That may sound illogical, so I will explain why they behave like that.
Not Enough Sun Hours
Every plant on our planet grows towards the sun. If it’s getting fewer sun hours than it requires, it will “mindlessly” grow in height before it is ready for it.
Fig trees won’t grow tall if they are not getting enough sun, but they will still grow taller than their trunks can support. That is closely connected to colder climates and likely why fig trees in conditions like these develop bush forms often.
You can provide more sunlight by pruning fig trees into an open-top shape. Additionally, I like to keep my potted fig trees near the south wall of my home. That way, they absorb reflected light and warmth.
You can even bring potted fig trees inside and use growing lights to provide them some extra light.
A cool trick that I haven’t found anyone was mentioning on the web is pointing growing light low towards the fig tree trunk and even shooting from down under. It is not relevant in the dormant season because the tree will not grow. However, once the growing season starts, you can trick the tree into growing its lower parts large instead of growing tall.
Too Much Water
Giving water to a tree promotes its growth, but since fig trees don’t like too much water, they tend to grow poorly.
By poorly, I mean growing weak wood and stems. The trunk especially will grow in height but stay as weak as it was before.
High humidity affects fig trees almost the same. Not only that, but fig tree wood starts to rot quite easily when given water in abundance.
Consider sheltering potted fig trees from excessive rain to avoid this problem. In-ground fig trees will experience problems with water when young, so there is still time to replant them on an artificially made ridge or elevated part of the garden.
Does Thicker Fig Tree Trunk Help With Surviving Cold?
Yes, a thicker fig tree trunk helps a great deal with surviving cold weather. That is one of the main reasons older fig trees have no trouble surviving winter, while young ones need more protection.
Sapwood covers a larger area in thicker tree trunks, so it’s less likely to freeze and stop sap flow to other parts of the tree. The sap is highly relevant even in dormant trees. Without it, the tree immediately starts drying, and then it dies.