Giant sequoia, Sequoiadendron giganteum (giant redwood), is not only the world’s biggest tree species, but both the biggest living thing in the entire world and the fastest growing (though not in the way you’d expect – keep reading).
General Sherman in Sequoia National Park is the record breaker – it’s 275 feet tall (imagine a football field stood on its end!) and the trunk is almost 37 feet wide at the base ¹. But how big do they usually get, and how fast do they grow? Are they a good choice for everyday property-owners and gardeners? What things do you need to consider?
As a general rule, giant sequoia grow 100 feet in their first 100 years in good conditions. Factors including drought, competition and sunlight have been noted to affect growth rate. 400-year-old sequoias range from 110 to 240 feet; thereafter most growth is in trunk expansion rather than height.
aniels, Gene, photographer, Photographer (NARA record: 8463941), Public domain, via Wikimedia Commons
Various websites will tell you that these trees grow to, for example, 200 feet. But how long does that take? Does it just stop growing then? And how come General Sherman so much bigger?
I’m a huge fan of these trees, and have geekily sifted through numerous books and read lots of academic papers to unpack all of this, and bring you reliable info on how quickly YOU can expect these trees to grow and how big they’ll get in YOUR lifetime.
How fast do young giant sequoias grow?
Most property owners have relatively young giant sequoias, by which I mean anything from 0 to 100 years old – unless you a) inherited one or b) were alive and tenderly planting your own seedlings several centuries ago.
During this time, giant sequoias grow at their most rapidly.
Not all giant sequoia will grow at the same rate, but some have been recorded in the literature² as achieving:
- 1 foot in height at age 2
- 8 feet in height at age 5
- 10-26 feet (one or two stories) at age 13 (another source³ 15-20 feet at age 15)
- 30 feet at age 18
A 1990 publication by P. Weatherspoon noted that giant sequoias under 50 years of age were noted to grow in height at 1.6 to 2.3 ft per year. The trunk diameter expanded by 0.5-0.8 inches per year.
So this seems to amount to 1-2 feet a year during the early stages of a giant sequoia’s life once it’s past the stage of being a small seedling. This is a similar speed to many young evergreen trees that are planted in good conditions.
If you’ve planted a giant sequoia or are planning to plant one, you could use this table as a guide for what to expect:
|Giant sequoia age
|Height (lower estimate) in feet
|Height (upper estimate) in feet
|Height in building stories*
If you’re planting a giant sequoia, watch this short video in which a man shows us some giant sequoias he planted 40 years ago.
Giant sequoias usually grow in a pyramidal fashion when in the open, and when ancient, lose their lower branches. However, they remain relatively columnar. General Sherman, while 275 feet tall, only has a maximum spread at the crown of 106.5 feet ¹.
Growth rate of maturing giant sequoias
We have several accounts of sequoias around a century old that have been measured.
Upon further review of the literature, we can find out what to expect from giant sequoias that live past 100 years. We have accounts of:
- 102-year-old sequoias averaging 125-135 feet tall ⁵
- 122-year-old specimens averaging 127 feet (the tallest was 154 feet) ⁵
For a visual aid here, check out this fascinating video. In 2017, A 105-year-old, 98-foot-tall giant sequoia was moved in Boise Idaho to make room for a campus expansion!
So most accounts agree that giant sequoias will reach around 100 feet in height in their first 100 years. This is the height of a 10-story building, so think carefully if you want to plant one of these!
As the trees become ancient, the upward growth slows substantially. According to Weatherspoon, at age 400, trees range in height from about 110 to 240 ft. At this stage, the trees can reach a maximum height, and the main growth is by expansion in the trunk’s width, as the tree puts on growth rings.
The maximum height of giant sequoias
The maximum height of mature Sequoiadendron Giganteum which survive to become ancient trees is believed to be between 250 and 275 feet 2,5, with record-breaking General Sherman at the tallest end of this scale. We’ve mentioned that it’s 275 feet tall. It’s barely putting on any additional height as the centuries roll by.
That’s not far off the height of Big Ben clock tower in London, which is 316 feet tall!
Giant sequoia trunk thickness and trunk growth
Giant sequoia’s renowned for its huge tree trunk in ancient specimens. General Sherman’s is an astounding 25 feet at chest height 1 (diameter at breast height or d.b.h. is a standard way of measuring trunks). How long will it be until your sequoia has a mighty trunk?
In 50-year-old giant sequoias, an increase in trunk diameter of 0.5 to 0.8 inches per year has been observed 4, while in ‘old growth’ ancient specimens, a much slower increase of only 0.04 inches (about 1mm) per year is seen 5.
Even though this expansion seems incredibly slow, it’s enough to increase General Sherman’s trunk volume by (according to estimates) between 40 and 51 square feet a year 4 – making it, amazingly, possibly the world’s fastest-growing tree as well as the largest!
Here are some recorded trunk thicknesses (diameter at breast height or d.b.h.) that I found within arboricultural literature: 2,4,5
|Giant sequoia age (years)
|Trunk diameter at breast height (d.b.h.) in inches
|2200-2700 (estimated age of General Sherman, world’s largest giant sequoia)
So from this data, we can gather that a giant sequoia that’s planted today will have a trunk that’s a foot or so thick after 15 years, achieving a width of 2-3 feet in the next century after that. Then it keeps on growing, potentially for millennia!
What makes giant sequoias grow faster, or slower
Shade and moisture
In general, giant sequoias are regarded as shade-intolerant. Seeds that land close together are likely to compete with one another so that one will shade out the other. If you’re planting a sequoia, it’s recommended it’s in a site that received ‘full sun’ if you’re hoping to reach its growth potential.
Those that are growing naturally in groves grow more slowly (particularly when young) because of both shade, and competition for moisture from surrounding vegetation. One paper described that seedlings up to 2-3 years of age grow poorly and abnormally if they’re shaded out by other plants 4. As a general rule, young giant sequoias need to be watered weekly during the warm months, and monthly through the cool months.
Drought has been a major factor in death of many ancient giant sequoias in recent years. This can occur directly or can predispose the trees to pest and disease problems, such as bark beetle infestation. I’ve written more about sick giant sequoias in this article.
Closely related to water is soil – giant sequoias like it to be well-drained and acidic. They’re known to be fairly intolerant of poorly-drained soil and struggle to grow well in such conditions.
Sequoias have shallow, fragile roots (particularly when young) and soil impaction from vehicles, machinery, or footfall can compact soil and affect the absorptive capabilities of the roots. This can impact sequoia in a similar way to drought and ultimately limit the growth potential of a young tree.
Read more about sequoias and soil here.
Climate and location
Giant sequoias growth has been found to be slightly less towards the southern reaches of their natural range in western North America 5. They’re tolerant to being buried in snow, but are susceptible to winter desiccation caused by wind, particularly in dry winters or when the ground is frozen. Again, in the linked article I’ve outlined the signs and impacts of winter injury and how to prevent it!
Giant sequoia root growth
What’s the root system of a giant sequoia like? Giant sequoias have a surprisingly shallow root system and don’t develop a deep taproot. It’s rather remarkable considering the vast bulk that these trees can carry.
3-year-old seedlings have roots that go down to about 14 inches 4. In massive specimens, the main roots are often 2 feet wide, but they spread outwards in a mat of tangled, thin feeders. When giant sequoias fall, these break off, leaving a dense proximal root system.
To give you an idea of what the roots of a massive mature specimen are like, check out this video – particularly the part where size is compared to a car!
Roots of mature trees often extend 100 feet or more from the trunk and can take up most of an acre in space 4. The roots furthest from the tree will mostly be within the uppermost 2 feet of soil 4 .
Giant sequoia lifespan
Felled specimens up to 3000 years old have been found (from counting rings in their stump). But it’s more difficult to tell the age of trees that are still upright! General Sherman’s estimated to be 2200-2700 years old 4.
However, very very few sequoias will live to become ancient trees like these. Many are outcompeted while still very small seedlings, while those surviving to adulthood will survive hundreds or thousands of years only through having ideal conditions of sun, moisture and soil, and fortunate avoidance of disease, wildfires, wind damage and lightning strikes.
What kind of diseases do giant sequoia get? Read about them here.
Can trees like General Sherman keep on living forever? Why, I wrote an article to tell you the answer!
How close can I plant giant sequoia to a house?
As a general rule, it’s best to plant giant sequoia at least 100 feet from buildings or other properties.
But have a look at the growth charts further up the article. It depends on how long into the future you’re thinking. If a tree survives to 100 years old it’ll reach about 100 feet. That’s about 4 times the height of a 2 story house. And then it may keep on growing and more than double that (albeit over hundreds of years).
The most important thing’s the safety aspect – a giant sequoia that topples (and in forests, they can and do) will destroy anything that should be unfortunate enough to be in its landing zone.
Also bear in mind the roots, which stay close to the surface even in very mature sequoias and can spread out to cover more than half an acre. These have the potential to invade foundations, pavements, driveways, septic tanks and fire hydrants.
As a tree enthusiast who can’t walk down the street without inspecting everyone’s yards, I constantly see trees that will eventually dwarf the very home of the person who planted it.
Think long term – maybe not on the millennial scale, but in a couple of generations your giant sequoia may truly live up to its name.
- “The General Sherman Tree”. Sequoia National Park. U.S. National Park Service. 1997-03-27
- Heald RC. Management of giant sequoia at Blodgett Forest Research Station. InIn: Weatherspoon, C. Phillip; Iwamoto, Y. Robert; Piirto, Douglas D., technical coordinators. Proceedings of the workshop on management of giant sequoia; May 24-25, 1985; Reedley, California. Gen. Tech. Rep. PSW-GTR-95. Berkeley, CA: Pacific Southwest Forest and Range Experiment Station, Forest Service, US Department of Agriculture: p. 37-39 1986 (Vol. 95).
- Size of the Giant Sequoia. National Park Service: The Giant Sequoias of California, 2007.
- Weatherspoon CP. Sequoiadendron giganteum (Lindl.) Buchholz Giant Sequoia. Silvics of North America. 1990;1:552-62.
- Dulitz DJ. Growth and Yield of Giant Sequoia1. of Giant Sequoia. 1986 Dec:14.