Chapter 129 Sequoiadendron giganteum; Sequoia sempervirens
129.1 Giant sequoia; California or coastal redwood
A group of giant sequoias in Sequoia National Park. Link to original image.
Coastal redwoods. Link to image source.
129.2 Soil: General Deciduous / Rich Conifer Mix
Ratio: 3 parts bark, 1 part grit
Add-ins: dolomitic limestone (~5 lbs/yd), Tree-Tone (15 lbs/yd)
pH: ~6.5 (slightly below neutral)
Moisture: consistent moisture is ESSENTIAL. Soil needs to be moisture-retaining but free-draining. Spray foliage once or twice a day to maintain high moisture on the needles.
129.3 Light
Routine: prefers full sun for 8 hours a day.
Summer: indirect afternoon sunlight during the hottest parts of the day. ry to keep the roots cool (90° F or less). If needed move the sequoias to a shadier spot so they don’t dry out. High temperatures (>100° F) are not harmful to the foliage but will kill roots.
129.4 Cultivation Notes
This is a Sequoia sempervirens styled to look like the iconic redwoods of California. Link to original image.
Both species do best in cool, moist climates with consistently high moisture levels. They do not tolerate being dry, or temperature extremes.
129.4.1 Potting & Root Pruning
Schedule: spring when the white feeder roots are actively growing.
Notes: one of the main redwood bonsai producers explains how to manage the roots this way:
We advise to avoid root pruning altogether unless you need to reduce the root ball size to fit into a smaller dish. Giant sequoias are able to self root prune to a large extent. Root pruning on a giant sequoia bonsai is performed successfully by slicing off a portion of the root ball with a sharp knife much like one would slice a block of cheese. Take only a conservative portion of about 20% or less. Never completely bare the roots of the giant sequoia. Do not be overly concerned with a root bound condition. Giant sequoias in the wild are naturally root bound for their entire existence.
Do your root pruning when the tree is dormant in the winter. Place the tree back in the shallow pot after root pruning and replace any missing portion of the root ball with good potting soil. Remove an equal or slightly larger portion of the tree’s branches at the same time. Avoid slicing roots solely from the bottom of the root ball. A portion of the bottom of the root ball can be successfully removed. The feeder roots tend to be most prevalent on the bottom of the root ball. Removing all of those can be harmful to the tree. If the root ball needs to be reduced in height remove soil and roots from the top of the root ball instead.
https://www.giant-sequoia.com/about-sequoia-trees/giant-sequoia-bonsai-care/
129.4.1.1 Top & Branch Management
Heavy pruning: should not be needed.
Fine pruning: Keep branches short.
Leaf pruning: Foliage prune by plucking hard once a year. Do itonce at the beginning of summer when the new shoots start to grow. Refine and tidy up in early September.
Wiring: wire in June. Watch for growth and remove when wire starts to cut in.
129.4.2 Feeding
Sequoias are heavy feeders that grow accordingly. Do not try to limit the size by cutting back on feeding. Feed regularly during the growing season using a mix of Espoma Tree-Tone (6-3-2) and Holly-Tone (4-3-4). The organics are preferred because they include beneficial soil bacteria in the mix, and have micronutrients.
If using soluble fertilizer, alternate between Miracle Grow and Miracid. Dilute them BOTH to 1/4 strength (not 1/2), and feed every other week.
129.4.3 Pests & Problems
Generally pest-free.
129.4.4 Winter Storage
The danger is not cold but dehydration. by cold wind. Ideally, place them in a well-drained cold frame and water the trees well before the first hard freeze. Bury the pot in pine needles or chopped leaves to minimize temperature swings.
129.5 Propagation Notes
Both species are highly adapted to very specific microclimates. As a result, they are difficult to grow successfully. I have successfully germinated seed one time, but lost the trees in their first year during our summer heat. If any had survived, I suspect they would have been killed by winter frosts.
My advice would be to purchase an older tree from an online specialty nursery.
129.6 Artistic & Styling Notes
A California redwood styled as a low informal upright. While the tree may be technically well done, I personally think it does not do justice to the species used. Link to original image.
Given how hard they are to grow, both species would look their best if they were styled to match their natural shapes. The natural trees resemble literati in terms of branch placement, but have very straight trunks instead of the bent shapes of typical literati.
To reflect native trees, the diameter of the branching spread should be around 6 times the diameter of the trunk at its base upon completion. The tree height should be 7 to 9 times the trunk diameter and the branching should start about halfway up the trunk.
Be patient. These trees mature at 400 years old, and can live to be 3000 years old. The flared trunk base and deeply fissures bark will take years to form.
129.7 Additional Information
129.7.1 Natural History
Giant sequoias are native to central California’s montane conifer forests, along the western slope of the Sierra Nevada Mountains (4500-8000 feet in elevation).
In its native habitat, young trees have a pyramidal-oval shape. As trees mature, they begin to lose branches from the lower part of the trunk. Mture trees can grow to 200-275’ tall, with trunks 15-20 feet in diameter and weighing 200 or more tons. Trees may live 2000-3000 years.
They can grow in USDA Zones 6 to 8 but will not reach the size of their native zone. Trees planted in the eastern US will grow to only 40-60 feet tall.
Coastal redwoods are native to an ~20-mile wide band of moist, foggy, coastal zones along the Pacific coast. They are fast growing, but also can live 2000 years or more. In ideal conditions they can grow to be the tallest trees in the world. One of the tallest specimens is 350 feet tall with a trunk diameter of 25 feet.
Outside of its native habitat, coastal redwoods are smaller, reaching just 60-90 feet tall. This is because the trees cannot carry water to that height by transpiration alone. They need routine (meaning near-daily) fog cover to provide their tops with sufficient moisture to reach those heights. The fog forms as moist air from the Pacific Ocean moves onshore and up the coastal slopes; the condensing water soaks the tree tops and is absorbed by the needles. There is some evidence that symbiotic bacteria and fungi living in the tree tops capture or synthesize additional nutrients that are absorbed with the condensed fog.
Technically they are winter hardy in USDA Zones 7-9, but they dislike wide temperature swings over the year.
129.7.1.1 Keeping Them Straight
It is very easy to confuse dawn redwoods (Metasequoia glyptostroboides), giant sequoias (Sequoiadendron giganteum), and coastal redwoods (Sequoia sempervirens). It also is forgivable, given that their genetic relationship to each other is still debated by taxonomists. Current thinking is that Sequoia is the result of hybridization many millions of years ago between Metasequoia and Sequoiadendron. This might seem impossible given that natural populations of dawn redwoods are limited to a few valleys in China. Millions of years ago though, they were widespread across the northern hemisphere, and their range overlapped with that of giant redwoods ( Metasequoia).
So how to separate them? The main differences are:
- Dawn redwoods occur naturally only in China. They are the shortest of the three species. They also have a strong tendency to form a distinctive candle flame-shaped crown. They are the only deciduous species of the three.
- Coastal redwoods are the tallest living things on Earth. Their range extends along most of the northern and central coast of California. They have bright green needles. They are evergreen.
- Giant redwoods are the largest by diameter and weight. Their natural range is extremely restricted to just a few slopes in central California. They have steel-blue to blue-green needles. They are evergreen.
Range map showing the natural distributions of coastal redwood (green) and giant redwood (pink). The large inlet half-way up the coast is San Francisco Bay. Link to original image.
