Dawn Redwood Questions - Nursery Stock

[Stickymatch]

Long time lurker and reader but first time posting.

I've been keeping indoor bonsai (ficus, jade, schefflera, etc.), off and on, for a number of years but never very seriously due to other hobbies and mostly already "trained" plants that I just kept trimmed as time presented itself. I learned some but honestly wasn't the best steward.

As I've aged and other hobbies have come and gone I keep getting drawn back to bonsai and the desire to learn more and challenge myself.

I have zero experience with outdoor trees for bonsai and was just gifted this beautiful Amber Glow Dawn Redwood due to an overbuy for a landscaping project. It's about 6.5' tall, trunk is 1" in diameter and currently in a 5-gal nursery pot. I'm in Zone 6b for reference.

Ultimate goals are to have a 3-4' tall formal style (probably ambitious). I know this will take some time and while l'm in no rush, if there are methods to speed up the process, I'm willing to learn and understand the pros and cons. I just want to learn and have fun.

So...what's the best way to thicken the trunk on these? Planting in the ground is currently not an option so containers will have to be the focus in the short term. Everything I've read says larger pots but l'm confused on size and frequency of repotting. What's the recommended size to go to from this 5 gal nursery pot? How long will it stay in that pot (2 years)? What pruning needs to be done during this time as I don't think you'd want to cut it down yet, right? In addition, what's the best soil to use for container growing?

Any info is appreciate and thanks for taking the time to read.

 

[Shibui]

There are no hard and fast answers to your questions because there are so many other factors that can influence growth rates.

Moving from tiny pots to large pots can have undesirable results but by the time you get to 5 gal size, doubling pot volume should not cause problems.
5 gal pot is already quite big. I suspect that tree has not really filled that pot so could still grow well for another year if you keep water and nutrients up to it in the current pot.
How large can you manage? Moving to a 10 gal pot should give you plenty of scope for growth if you really want to upsize.
Larger pots help even out temp and moisture fluctuations which definitely slow growth. I suspect that's more of a factor in growth than the physical space for roots.

Most of the early growth of Dawn Redwood is up as you can already see. How tall can you afford to let it grow? Taller means more problems with wind so at some stage you may need to temporarily sacrifice some thickening and chop the trunk to reduce height. The effect is only temporary because the tree will respond to pruning with lots more growth so soon replace what was lost.

 

[Stickymatch]

There are no hard and fast answers to your questions because there are so many other factors that can influence growth rates.

Moving from tiny pots to large pots can have undesirable results but by the time you get to 5 gal size, doubling pot volume should not cause problems.
5 gal pot is already quite big. I suspect that tree has not really filled that pot so could still grow well for another year if you keep water and nutrients up to it in the current pot.
How large can you manage? Moving to a 10 gal pot should give you plenty of scope for growth if you really want to upsize.
Larger pots help even out temp and moisture fluctuations which definitely slow growth. I suspect that's more of a factor in growth than the physical space for roots.

Most of the early growth of Dawn Redwood is up as you can already see. How tall can you afford to let it grow? Taller means more problems with wind so at some stage you may need to temporarily sacrifice some thickening and chop the trunk to reduce height. The effect is only temporary because the tree will respond to pruning with lots more growth so soon replace what was lost.

Hi Shibui....thanks for your reply.

I'm not sure how much it's filled the 5 gal. pot. My guess is aligned with yours that it's probably hasn't. I'm tempted to lift it out to check but I don't want to disturb it too much and it would require me to dry it out some so I don't create a mess.

I could go pretty large with the pot as I have a patio facing east to get morning/early afternoon sun and then semi-shaded during the hottest parts of the day. I could also allow it to grow fairly tall as well but that will also cause issues, as you said, with wind but also transport to a more secluded area if temps drop too low during the winter. A 10 gal. pot would definitely be manageable and allow portability if needed.

Any recommendations for soil composition and fertilizer?

 

[dbonsaiw]

You picked a good species for a first time outdoor tree. They are hardy, very fast growers and can take a beating. In a large pot, I personally don't see a need to move it around based on cold and don't move mine around when they are in larger pots (I have one in a bonsai pot that gets mulched in for the winter). For more growth, you could also just put the pot on the ground and let the roots escape into the ground. They grow so aggressively that you could (should????) cut it down every year or so to get better taper. This is one of those species for which a large trunk/large bonsai is possible in a "reasonable" amount of time.

 

[Stickymatch]

You picked a good species for a first time outdoor tree. They are hardy, very fast growers and can take a beating. In a large pot, I personally don't see a need to move it around based on cold and don't move mine around when they are in larger pots (I have one in a bonsai pot that gets mulched in for the winter). For more growth, you could also just put the pot on the ground and let the roots escape into the ground. They grow so aggressively that you could (should????) cut it down every year or so to get better taper. This is one of those species for which a large trunk/large bonsai is possible in a "reasonable" amount of time.

Thanks for the reply. I've seen it multiple times in posts that I've been reading and you mention it as well is taper. Where do you decide to cut to then grow out a new leader? How often? If I wanted a 48" tall tree, am I looking at around a 6-8" diameter trunk? How do I know when and where to cut to ultimately achieve this over "x" period of time?

Maybe this all comes with experience, but I also can't find a general consensus either.

 

[dbonsaiw]

Thanks for the reply. I've seen it multiple times in posts that I've been reading and you mention it as well is taper. Where do you decide to cut to then grow out a new leader? How often? If I wanted a 48" tall tree, am I looking at around a 6-8" diameter trunk? How do I know when and where to cut to ultimately achieve this over "x" period of time?

Maybe this all comes with experience, but I also can't find a general consensus either.

I'm still learning as well. I set out a few years back to do basically what you are doing, except I planted it in the ground. After 3 years of unhindered growth, the tree was nearly 25 feet tall and about 6" thick. It was cut back this spring to 18" or so and I will work on a new leader over the next few years (assuming I don't chop it lower first). The goal initially was to cut the tree down to 1/3 of its final size and then start to build the next section of trunk.

I have a trial and error way of learning (lots of error) and lately I seem more inclined towards a cut and grow method of developing trunks (but I'm still kind of clueless). Maybe the more experienced folks will chime in, but I don't see the cut and grow method to be as mathematical as the alternative version (one-third rule). Rather, the tree is cut back to a low point and the tree allowed to grow again. Next year, it is cut back a little higher than where you were a year before and continue this process year after year. The year of growth adds to the girth, while the more frequent cutting adds to movement and taper. On a more straight-up deciduous tree (like a JM), I would cut back to a lower node.

Conceptually, we are always growing for size and cutting for taper and movement. The question is simply how you want to go about this. You can let the tree grow freely until the trunk is basically the size you want and then cut the tree back to 1/3 of its final height. Then grow the tree out again until the new leader is big enough (2/3 the size of the lower trunk????) and cut back so that the new section of leader is 1/3 of the way to the final height - rinse lather repeat. The pros are faster growth. The cons are bigger scars and I'm finding more clunky-looking movement that keeps bringing me to "S" shapes. Alternatively, by using a cut and grow method you will get slower thickening, but get smaller scars and much better movement and taper. I'm doing this too short a time to decide which method gets one to a bonsai in a pot faster, but I seem to moving more towards cut and grow.

 

[Jrmcmich]

I'm still learning as well. I set out a few years back to do basically what you are doing, except I planted it in the ground. After 3 years of unhindered growth, the tree was nearly 25 feet tall and about 6" thick. It was cut back this spring to 18" or so and I will work on a new leader over the next few years (assuming I don't chop it lower first). The goal initially was to cut the tree down to 1/3 of its final size and then start to build the next section of trunk.

I have a trial and error way of learning (lots of error) and lately I seem more inclined towards a cut and grow method of developing trunks (but I'm still kind of clueless). Maybe the more experienced folks will chime in, but I don't see the cut and grow method to be as mathematical as the alternative version (one-third rule). Rather, the tree is cut back to a low point and the tree allowed to grow again. Next year, it is cut back a little higher than where you were a year before and continue this process year after year. The year of growth adds to the girth, while the more frequent cutting adds to movement and taper. On a more straight-up deciduous tree (like a JM), I would cut back to a lower node.

Conceptually, we are always growing for size and cutting for taper and movement. The question is simply how you want to go about this. You can let the tree grow freely until the trunk is basically the size you want and then cut the tree back to 1/3 of its final height. Then grow the tree out again until the new leader is big enough (2/3 the size of the lower trunk????) and cut back so that the new section of leader is 1/3 of the way to the final height - rinse lather repeat. The pros are faster growth. The cons are bigger scars and I'm finding more clunky-looking movement that keeps bringing me to "S" shapes. Alternatively, by using a cut and grow method you will get slower thickening, but get smaller scars and much better movement and taper. I'm doing this too short a time to decide which method gets one to a bonsai in a pot faster, but I seem to moving more towards cut and grow.

At first confused by your cut and grow vs chop as technically both cut and grow but assume your referring to much smaller cuts which produces smaller scars to heal. @Shibui discusses this often and uses that method. I do agree larger chops do seem to produce more clunky bends but only have a few big enough where I’ve been doing that myself. Too many sticks I need to plant in ground next year

 

[rockm]

At first confused by your cut and grow vs chop as technically both cut and grow but assume your referring to much smaller cuts which produces smaller scars to heal. @Shibui discusses this often and uses that method. I do agree larger chops do seem to produce more clunky bends but only have a few big enough where I’ve been doing that myself. Too many sticks I need to plant in ground next year

Do a search on bald cypress trunk reduction. Mostly the same procedure. Species is pretty strong grower. Like BC it can take drastic reduction and fill in matching taper pretty quickly (quickly is relative a few years of growing out and chopping back. Sounds scary but it’s not really.

 

[Shibui]

Any recommendations for soil composition and fertilizer?

Trees in large grow pots do well in almost any reasonable soil mix. No need for special soil mix at this stage. I use the same mix for all trees here. Not sure what's available in your area but I'd probably just buy a bag of good quality potting soil. Dawn Redwood love water so waterlogging is rarely a problem. Many of us sit the pots in a water tray through Summer to keep them happy.

Fertilizers are all good. Trees cannot read so they don't care what brand you use. They only care if there's nutrients and all fertilizers should have nutrients.

48 inches is 4 foot tall. That's a big tree.
Consider the weight - you WILL need to move the tree - to get sun on all sides, to overwinter, to repot. don't be fooled into thinking it will be light because it's a bonsai. tree trunk that size will weigh 20-30kg, add a pot at say 5kg, damp soil - 5-10kg. The whole thing could weigh 45 kg - 100lb, maybe more!
Consider the size of the pot it will need - cost of such a pot? Sourcing a big pot?

As I get older I'm moving to smaller and smaller bonsai so I can manage them better. Maybe you are still young and silly and think you can manage heavy pots and trees? Maybe you have fit, young friends who will help?

Thanks for the reply. I've seen it multiple times in posts that I've been reading and you mention it as well is taper. Where do you decide to cut to then grow out a new leader? How often? If I wanted a 48" tall tree, am I looking at around a 6-8" diameter trunk? How do I know when and where to cut to ultimately achieve this over "x" period of time?

You can't find consensus because there's no single correct recipe to create a bonsai. Lots of slightly different methods all end up with good results.
Generally, the first chop is usually around 1/4-1/3 of planned final height. Then build the trunk with successive chops above that initial one, gradually decreasing the added height as you go - Something like: Chop 1 - 12", Chop 2- 18", Chop 3 - 22", chop 4 - 26", etc. That seems to give reasonable taper in the developing trunk and branching in good locations.
First chop might be at 2-3 years old, 2nd chop at 5-6 years, 3rd chop 7 years, 4th chop 7.5 years, etc.

 

[dbonsaiw]

Do a search on bald cypress trunk reduction. Mostly the same procedure.

Apropos of the similarities between BC and DR, attached are some illustrations by Zach Smith on developing BC.