Sequoia – cultivation and care as a tree and bonsai

Sequoias are the record holders among trees in three directions – the largest, the thickest and the oldest. No wonder that tree lovers almost adore the sequoia tree, no wonder that there are gardeners who dream of planting a sequoia tree or even shaping it into a bonsai. If you are one of them, you will learn a lot about the cultivation and care of the sequoia tree as a tree and as a bonsai in the following article.

Which sequoia should it be?

So you would first have to decide on one type of sequoia tree. There are three sequoias:

  • The coastal redwood Sequoia sempervirens is the sequoia that can hold the record when it comes to the tallest trees in the world. The most famous of these “California Redwoods” or “Coast Redwoods” is located in Redwood National Park in California and is called Hyperion. At 115.55 meters, it is currently the tallest tree in the world.
  • The mountain sequoia or giant sequoia is botanically called Sequoiadendron giganteum. It competes with a Mexican bald cypress for the title of “thickest or most voluminous tree in the world”. The title contenders: A Mexican bald cypress in Santa María del Tule (Oaxaca, Mexico, the trunk diameter was measured at 11.42 and 14.05 meters) and the General Sherman Tree (Sequoia National Park, California, USA, trunk diameter 11.1 meters) .
  • The primeval sequoia Metasequoia glyptostroboides, on the other hand, remains a real dwarf with a final height of around 40 meters. But he can come up with a really amazing age. It is about 70 million years old, which is 5 million years older than the dinosaurs. It was dying out, too, but only nearly. A “living fossil” survived in a hidden mountain region in China, was discovered in 1941 and has since spread out into the world again from there. In many places it is already represented as an ornamental tree in parks and gardens.

Small decision-making aid when choosing

The sequoia trees are amazing. However, there are arguments why you should only put a sequoia tree in your garden after careful consideration. Which variety should be considered just as carefully, here are a few key points:

Coast redwoods

Sequoia sempervirens are evergreen, their needles look a bit like yew needles. You would not see these needles very long if you put a coastal redwood in your garden: It grows up to 2 meters per year, with the foliage in the upper area. On the other hand, the rest of your property would become more and more bare, because the coast redwood conquers large areas with its shallow roots. It is sure to completely root a German garden of average size. It is then difficult to introduce other plants.

Mountain sequoia trees

Sequoiadendron giganteum stay green all year round. Their needles are a little finer than those of the coastal redwoods. Mountain sequoias look pretty much like a Christmas tree when they are young. If you want to plant a mountain sequoia tree in a freely accessible piece of forest, you should probably expect it to become a Christmas tree.

In the garden there is a completely different danger: mountain sequoias are shallow-rooted in and of themselves. In trees growing in our latitudes, however, tap roots have already been dug up, which went down to almost 2 meters. These roots were dug up because a sequoia tree, like any tree, seeks water, in case of doubt also where a sewer goes through. However, the roots of the sequoia tree can cover amazing distances and develop amazing strength in this search. Your mountain sequoia wouldn’t be the first sequoia to cause sewer rehabilitation.

Primeval sequoia

The Metasequoia glyptostroboides sheds its needles in autumn, but is certainly the most attractive sequoia in its summer dress. Ancient sequoias are said to be very good carbon sinks. As they grow, they take up a lot of carbon dioxide from the air and store it in their biomass. That is why there should already be initial attempts to use primeval sequoia trees in our forestry.

The primeval sequoia is also the species of sequoia that is said to get along best with the climate in Germany. Although the climate in its Chinese homeland is a little milder than here, it should not grow any worse in Germany than in Sechuan. In contrast to mountain and coastal sequoia trees, young primeval sequoias can be planted in the garden in the first year. Only the first winter should be done with some winter protection. From the second year on, the primeval sequoia trees should be able to withstand temperatures of up to minus 30 degrees.

Incidentally, for all sequoia trees you should take a very close look at the local tree protection law before planting them in the garden. Because the regulations are partly formulated in such a way that it states what can be felled, every other tree is then actually protected – even if it has now reached dimensions that unfortunately put your house in shadow all day …

Stratifying the seeds of the coastal redwood

If you want to grow a small coastal sequoia, the first thing you need to do is stratify the seeds. The coast redwood’s coastal sequoia seeds are quite dark, not as flat as the other sequoia seeds, and they look a little misshapen and uneven.

Stratifying is the simulation of a cold season, because in nature seeds should germinate in spring and the cold season before that gives them the starting signal. In the season in which the seeds ripened, they were given a sprout inhibitor so that they do not germinate straight away in autumn; hardly a seedling would survive the winter. This inhibition of germination is broken down by the winter cold, and the seeds are ready in spring. For the gardener, the cold season of the year simulates the refrigerator in which they go to stratify, for different lengths of time, depending on the seeds. A duration of 5 to 7 days is recommended for the coastal redwood, the refrigerator should be set to 5 degrees.

In case of doubt (if the first seeds of the batch have not germinated, for example) it is recommended to stratify the next seeds longer, the specified stratification times may differ from source to source. Perhaps the safest thing to do is to try to imitate winter in the tree’s home in terms of duration and temperature?

The coastal sequoia seeds do not need to be soaked after stratification, they go straight to the ground.

Stratifying the seeds of the mountain sequoia

The seeds of the mountain sequoia are light to medium brown and are somewhat reminiscent of coffee beans. For the mountain sequoia, the recommended stratification temperature is also 5 degrees, there are many indications about the duration, from three days to two months. It is reported on the Internet that half of the seeds can be germinated with a stratification period of two weeks, which is a huge germination rate for sequoia seeds. The sequoia seeds should be soaked in room warm water after the stratification has been completed. How long cannot be determined exactly, between 12 and 24 hours.

Stratification of the seeds of the primeval sequoia

The primeval sequoia seeds look similar to those of the mountain sequoia tree, maybe a bit lighter, and probably a little flatter too.

The primeval sequoia seeds are stratified at the same temperature as the other two; the recommended stratification period is 5 to 10 days. Then the seeds should be soaked in lukewarm water for 12 hours.

Growing the sequoias

When the seeds have stratified and possibly soaked, they are allowed into the potting soil. Which potting soil is recommended is also a matter of dispute, here are the variants:

  • One part each of garden soil, humus and sand
  • reine Kokoserde
  • Coconut soil with crushed eggshells
  • Coconut soil with wood ash could be logical because coastal redwood and mountain sequoia germinate in the wild after forest fires.

The seeds are distributed on the potting soil and loosely covered with earth, sequoias are light germs. The soil should be kept moist, but not wet, throughout. This works well if you use an indoor greenhouse or cover the nursery pots with glass or foil. You should then ventilate regularly, otherwise mold could develop quickly.

The germination period for the coastal redwood and the mountain redwood should be between 2 to 5 weeks, for the primeval sequoia one to three weeks.

Further rearing of the sequoia trees

When you have managed to grow stable young plants from the seeds, you have to prick them out, that is, separate them. It is recommended not to prick out too early, five weeks after germination at the earliest.

The sequoia trees should be planted in nutrient-rich soil that is kept well moist, the young plants must be watered regularly.

In summer, the small sequoia trees are welcome to go outside, in a sheltered place that does not get direct midday sun. That should even work better than the rearing in the house, where the trees often go moldy or buckle. With the young plants in particular, it should be very important that they are anything but pampered. You can safely expose them to the wind and the weather, the stronger the trees will grow.

Further rearing should take place in a protected location in partial shade, without waterlogging and initially with winter storage in the house. There the sequoia shouldn’t be placed near the heater, because the air would be too dry for it.

Coast redwoods and mountain sequoias can be planted outdoors from the third year. Primeval sequoia trees after their first overwintering. In the case of grim cold, young trees should get some protection of the root system. The best time to plant a sequoia tree in the garden is in September and October. In the garden, the sequoias want to enjoy a location with full sun.

Caring for the sequoia tree

Once something has developed that really deserves the name tree, maintenance is no longer complicated:

  • If the sequoia is exposed to the blazing sun, it needs to be watered well.
  • Especially in the summer months, you really need to be careful not to let the roots dry out.
  • In its first years of life, the sequoia gets some fertilizer every spring.
  • As the sequoia grows larger, it is regularly pruned for thinning.

The tree as a bonsai

Because not very many gardeners here have a plot of land that is big enough for a sequoia tree and hardly any gardener has their own forest, sequoia trees are also often grown as bonsai.

It seems a bit absurd to want to turn the thickest and tallest tree in the world into a bonsai. In the case of the mountain sequoia, however, the growth-retarding pruning should definitely work. Seeds from the coastal sequoia are also offered for cultivation as bonsai. How easily they can be persuaded by the constant pruning not to grow 100 meters high is another question. The most widespread is of course the bonsai from the primeval sequoia tree.

 

The bonsai sequoias are pruned and wired as usual with bonsai. In spring and summer you can simply cut off too many young shoots. It is said that Japanese gardeners imitate the wind by stroking the young plants, which are supposed to react with compressed growth so that they are not kinked by the wind. Dead wood in the primeval sequoia is best removed during the winter months because it is then bare.

The sequoia bonsais are well placed by the window in partial shade. You want sun but not too much heat. All sequoias are of course very fast-growing bonsai that need quite a lot of nutrients. Therefore, you should fertilize them every three weeks in the first growth phase. Even with sequoia bonsais, the soil should always be kept well moist, they also don’t like the dry air above the heater. From the third year the sequoia bonsai can also be kept in the garden. It spends the winter sheltered in a cool, bright room, it continues to be watered.

Conclusion
Sequoias are absolutely fascinating, both as a tree and as a bonsai, but not necessarily easy to grow. If you have the patience, however, you will at some point have to deal with trees that are very easy to care for, which you can proudly report on in the fairly large German sequoia community.

Kira Bellingham

I'm a homes writer and editor with more than 20 years' experience in publishing. I have worked across many titles, including Ideal Home and, of course, Homes & Gardens. My day job is as Chief Group Sub Editor across the homes and interiors titles in the group. This has given me broad experience in interiors advice on just about every subject. I'm obsessed with interiors and delighted to be part of the Homes & Gardens team.

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