Chapter 108 Metasequoia glyptostroboides

108.1 Dawn redwood

A dawn redwood just starting out in training. When mature, most dawn redwoods have a distinctive candle-flame shaped crown that projects well above the surrounding canopy. To recreate this, the stylist will need to clip back some branches while letting others build out in thinner areas. Link to original image.

108.2 Soil: Moist Deciduous Mix

Ratio: 4 parts bark, 1 part grit

Add-ins: dolomitic limestone (~5 lbs/yd), Tree-Tone (15 lbs/yd)

pH: ~6.5 (slightly below neutral). Likes more acidic, ericaceous soil too.

Moisture: Ample to regular

Dawn redwoods are very much like bald cypresses that they will adapt to a variety of soils, but prefer moist, deep, well drained soil. The best way to ensure proper moisture levels is to reach down an inch or two into the soil with a finger. They are not drought tolerant in pots.

108.3 Light

Does best in full sun (six hours of direct, unfiltered sunlight each day.) Protect first-year seedlings from strong summer sun. No additional protection is needed in summer.

108.4 Cultivation Notes

108.4.1 Potting & Root Pruning

Repot every other year in the springtime. The strongly growing roots fill up the pot quickly and soon push the rootball up in the pot. Considerable root pruning is inevitable each time they are repotted.

108.4.1.1 Top & Branch Management

Best trained in a formal or informal upright style. Also works very well for clump and slanting styles, and for bonsai forests.

Dawn redwoods often produce a lot of new buds, especially near scars from pruning. Unneeded buds should be removed immediately. Twigs with long internodes should be pruned in spring before the new buds open.

Prune in the summer by trimming back new shoots.

If needed, wire and shape branches from early winter to early spring when the tree is dormant. Leave wire in place for 3-6 months, and make sure damage to the bark is prevented. It is better to avoid wiring, a let the tree grow in a natural shape.

Pinch back green tips throughout the course of the year.

108.4.2 Feeding

Fertilize from late spring to late summer with a well balanced fertilizer. Slow-release formulations are best. Studies from North Carolina State University and the University of California, Davis found that dawn redwoods do best with fertilizers in a 3-1-2 ratio (ex. 12-4-8 or even diluted 18-6-12). Dawn redwoods also thrive with iron-rich fertilizer or plant food.

Avoid fertilizers with nitrogen content any more than three times higher than phosphorus or potassium, as high-nitrogen fertilizer may exacerbate diseases such as redwood canker. Fast-release nitrogen-rich fertilizer is especially harmful.

Do not feed in the fall. Dawn redwoods will continue growing if fed, and this new foliage will be damaged by cold.

108.4.3 Pests & Problems

I have never had any pests that affected my dawn redwoods.

108.4.4 Winter Storage

Store in mulch outdoors. Do not let them dry out. Protect from extremely cold weather. No other special precautions are needed.

108.5 Propagation Notes

Dawn redwood is easily confused with bald cypress (Taxodium distichum), especially as seedlings. The needles on dawn redwood are opposite, meaning they are positioned directly across from each other on the stem, while bald cypress needles are alternate (staggered).

Dawn redwoods produce cones the size and shape of seedless white grapes. I tried several times to grow them from seed, but never succeeded in getting more than 1-2 seedlings that usually died within a couple months. I learned that dawn redwoods have very particular requirements for seed germination and survival.

First, like other wind-dispersed seeds, they require light to germinate. Seed buried in even 1/8th inch of soil will not break. That explained why mine never grew. Second, like bald cypress, dawn redwood seeds need very moist to nearly water-saturated soil all winter to break dormancy. Third, the new seedlings are EXTREMELY sensitive to drying out. The first time the top inch of soil dries out, even for just a day, the seedlings die.

I learned that the best way to get dawn redwoods is not to sow the seed, but harvest them from beneath a nurse tree. We have two such trees behind the biology building on campus that bear and drop hundreds of cones each year. They are in a protected area adjacent to two magnolia trees, so the soil beneath these trees stays very moist all winter. Starting in mid-February, I check every few days to see if any seeds have germinated. Usually they all come up in a flush sometime before mid-March. Once the seedlings emerge, I watch the weather carefully. I want the seedlings to stay in the ground as long as possible, but if the weather is going to warm up suddenly or we are expected to have a dry spell, I collect immediately.

The latest I have ever been able to push collection is the middle of April. I rarely see any seedlings after the end of April.

I bring a tub with black topsoil and bark mix and a cheap metal spoon. I lift seedlings individually (they have very shallow roots) and position them in the soil immediately. Back at home I put the tub in shade and keep it thoroughly watered.

I collect a lot of seedlings at once because survival of lifted seedlings is <50% in the best years, and can be as low as 10% if I get to them too late. I also expect to lose another 20% over the course of the year. After a year in the collecting tub, trees are potted up to 4-inch or 1-gallon nursery pots. About 10% of the seedlings moved to nursery pots also die; I am not sure why. Once they are in 1-gallon pots though, seedlings stabilize and start growing quickly.

I used to be concerned about losing so many young seedlings until I talked to a conifer grower who confirmed that my seedling losses are similar to what they see normally in commercial production.

108.6 Artistic & Styling Notes

Naturally growing, well-proportioned mature dawn redwoods have a 4:1 height:width ratio. Unlike many trees, they have mostly upturned branches, even at the bottom of the crown.

108.7 Additional Information

108.7.1 Natural History

If you do not know their story, fossils of dawn redwood are found throughout the Northern Hemisphere, ranging in age from ~100 million to ~10 million years old. All traces of their fossils disappeared after that, which is why it was assumed to be extinct. It was the dominant conifer of the north; extensive forests once occurred as far north as Ellesmere Island and Axel Heiberg Island (northern Canada) at around 80° N latitude.

In 1944, a small stand of an unidentified tree species was discovered in China by Zhan Wang in Modaoxi, in Lichuan County, Hubei. In 1948 it was identified by Wan Chun Cheng and Hu Hsen Hsu. In 1948, the Arnold Arboretum of Harvard University sent an expedition to collect seeds and they sent seedling trees to various universities and arboreta worldwide for growth trials.

A few natural groves still exist in Hubei’s Lichuan County, China, where it is called a “water fir.” Most of the natural groves have fewer than 30 trees each, but one grove has around 5,400 trees.

There is interest in re-establishing dawn redwood groves outside of China. One such effort is the Crescent Ridge Dawn Redwoods Preserve, located in the Sauratown Mountains here in Piedmont North Carolina.

108.7.2 In Cultivation

Physically, our modern dawn redwood appears identical to its fossilized ancestors. It seems not to have changed in more than 60 million years.

It is thought that all cultivated dawn redwoods in the world today are descendants of the original Arnold Arboretum specimens.

In terms of growth habits, dawn redwoods resemble bald cypresses. However, their closest relatives are Sequoia sempervirens (coast redwood) and Sequoiadendron giganteum (giant sequoia) of California. Dawn redwoods are the smallest member of their family, but still grow to at least 165 feet tall.

They are more distantly related to cypresses, junipers, and cryptomeria.