There are hundreds of different trees around the world, and they are essential for a healthy, clean environment. Since trees are a common and vital part of our world, it’s good to know how they grow. So, you might be asking yourself if trees grow from the top or bottom.
Trees primarily grow from the top because most of the growth occurs at the branch tips, where meristems are located. Meristems are places where the most cell division occurs (and, in turn, where the most growth occurs). Meristems are also found in tree roots, trunks, and buds.
This article will discuss how trees grow in greater detail. Read on to learn more about this important and exciting topic!
Why Do Trees Grow From the Top?
Trees grow from the top because the growing cells are located at the branch tips and tree shoots. Therefore, trees get longer and taller because of the cells in these locations. However, roots are essential for growth because they provide the tree’s body with nutrients and water.
Plus, the meristems at the roots of trees allow the roots to expand through the soil. Tree roots will grow in any direction that suits them. While it’s common for them to grow outward, many roots will grow up toward the surface of the earth, where there are more significant amounts of water, oxygen, and essential nutrients.
Still, when you notice a tree getting taller each year, it’s because it’s growing from the top. In the next section, I’ll discuss how this works in more detail.
Understanding How Trees Grow
The science behind how trees grow can be highly complicated if you get into the details. Luckily, for most people, it’s only necessary to understand the basics. The first thing to note is that trees have three main areas of growth:
- The buds on the branches and twigs
- The root tips
- The cambium section
Below, I’ll discuss each section in detail.
Buds Grow on Branches and Twigs
Some prominent growth places on a tree are the twigs and branches. This growth occurs directly at the tips, where buds form and grow.
Eventually, these buds turn into leaves and flowers (or fruits if it’s a fruit tree), and they expand the height and diameter of the tree. This is why most people say that trees grow from the top rather than the bottom, and they’re technically correct.
The bud growth at the branch and twig tips allows the tree to grow taller, but this process doesn’t occur all year long for perennials. During winter, perennial trees will go dormant, and growth at the branch tips will halt; this also means buds won’t form on the branches and twigs during winter.
However, growth occurs all year long for evergreen trees.
Root Tips Grow in All Directions
Another place where lots of growth occurs is the root tips of a tree. Although trees technically grow taller from the top, the roots are still essential for nutrients and water transportation. For example, if the roots don’t receive enough water from the soil, they won’t be able to grow anymore.
They also won’t be able to supply the rest of the tree with water, meaning it will likely die eventually. Without healthy roots, your tree will become unhealthy and endangered.
It’s also important to note that roots don’t grow in a particular direction, unlike the rest of the tree. While the body of a tree tends to grow mostly upward, roots can grow in all directions.
You may be wondering what factors determine where roots will grow, and the answer is simple: tree roots will grow toward the most favorable location (i.e., the place with the most water, nutrients, and oxygen). Roots can grow upward, outward, and downward.
While the growth of tree roots doesn’t necessarily affect how the rest of the tree grows (i.e., how it grows from the branches), the roots are vital for the transportation of nutrients and photosynthesis.
The Cambium Section Grows and Increases Tree Width
The cambium section of a tree is the part of the trunk that grows. It is located between the xylem and phloem layers of the tree. The meristems at both the branch tips and the cambium section increase the tree’s diameter. But while the meristems at the branch tips also help the tree grow taller, the meristems at the cambium don’t.
Each year, the cambium produces new bark and wood. As a result, cambium growth allows trees to get wider, increasing the tree’s dripline. The cambium also encourages the development of the tree’s roots and stems.
Can Tree Roots Grow Once a Tree Is Cut?
Tree roots can’t grow once a tree is cut because trees grow primarily from the top, not the roots at the bottom (unlike many other plants). While the roots must provide nutrients to the rest of the tree, it’s also essential for the leaves to give nutrients to the roots.
Without this dynamic, the roots won’t be able to grow, and the tree likely won’t grow back. However, in rare cases, some new growth may occur after cutting down a tree. If this happens when you don’t want it to, you should remove any new growth as soon as you notice it. Eventually, the problem should go away.
You should only worry about the roots continuing to grow if you notice new sprouts appearing. If you don’t see anything, the roots will likely stop growing and eventually decay in the ground. It’s important to note that some trees are more likely to redevelop than others.
For example, trees of heaven are invasive and are more likely to continue growing after being cut down.
As you know from earlier in this article, trees grow from the top because the buds at the branch tips are what give trees their increased height (and diameter). So, once you cut down all these parts of the tree and leave the roots behind, there’s usually no way for the tree or roots to continue growing.
Do Trees Ever Grow From the Bottom?
Trees never grow from the bottom. The increase in height always comes from buds forming at the branch tips. Although growth occurs at tree roots, this growth doesn’t directly contribute to the growing stature of a tree.
That’s not to say that a tree’s roots aren’t important—they certainly are. A tree’s roots must continue thriving to supply the branches with the nutrients they need to keep producing and growing new buds.
However, it’s always important to remember that trees never actually grow from the bottom.
The Importance of Proper Soil for Tree Growth
Since trees grow in height from the top (rather than the bottom), some people might assume the soil and roots don’t matter.
However, this is far from the truth. A tree growing in the appropriate soil conditions will surely last longer (and remain healthier) than a tree surrounded by unfavorable soil.
The soil is the first thing you should consider when you want to plant and grow a tree. Trees receive water and nutrients from the earth, so if it doesn’t have enough of these (or if it has too much), the trees won’t be able to grow and thrive as much as possible.
Soil Should Be Rich in Essential Nutrients
When growing a tree, the soil should have adequate phosphorus, potassium, and nitrogen, among other micronutrients. Thankfully, these nutrients occur naturally in the earth. However, there isn’t always enough of them to support tree growth. You can get a soil test to learn more about your soil’s required nutrients.
If a tree is surrounded by soil with these vital nutrients, the roots can support the rest of the tree, encouraging growth from the top.
Soil Should Be Well-Draining
It’s also essential to ensure the soil is well-draining so the roots don’t get waterlogged. You want the roots to have enough water to remain hydrated and support the rest of the tree’s growth. However, you don’t want there to be so much water that the roots get saturated.
You also want to make sure the soil isn’t compacted. Although some trees won’t have a problem growing in hard clay soil, others will struggle to grow. When the earth is rigid and compacted, it can be challenging for the roots to grow freely. As a result, they become damaged and can no longer support the rest of the tree.
Eventually, the tree will stop growing because it’s no longer receiving nutrients from the roots, so the buds can no longer form and grow from the top.
Trees grow from the top because the buds develop at the branch tips, increasing trees’ height and diameter. Although growth occurs in other parts of trees, the branch tips are what give them their increased height.
The root tips and the cambium section are the other places that experience growth in trees. The root tips grow primarily under the soil and can grow in many directions. The cambium is the part of the tree trunk that grows. While trees don’t grow from the bottom, the roots are still vital for trees’ overall health and growth.