Repotting tips for beginners.

[Beng]

Most of you already know how to repot, but for those that don't and with repotting season upon many of us I thought this post might help some.

Repotting and Root Pruning

#1 Remove any wire holding the tree into the pot.

#2 Root Removal: You base the amount of roots you remove on the age of the tree, and the state of the root system as a whole. If you pick up a nursery plant with a large tap root but lots of white feeder roots and the tree is healthy it's usually ok to reduce the tap root by 1/2. For deciduous trees with a large amount of feeder roots cut off the main tap root completely but allow about 1-1.5 inches beneath the feeder root system for potential dieback. View attachment 31954 For healthy evergreens with strong feeder roots you can remove 1/2 to 3/4 of the tap root. Make sure you retain some of the soil when repotting evergreens Pines/Junipers. If the tree has week feeder roots try to keep 1/2 to 3/4 of the tap root and pot it into a faster draining bonsai mix. The following year if strong feeder roots have developed you can remove a portion of the tap root.

If the tree is severely root bound first cut the root ball in 1/2 with a saw. Comb out the remaining roots starting at the bottom of the root ball where you cut. Once this has been loosened move onto the sides of the root ball.

If you are starting with an established bonsai your goal is different. Your goal is only to refresh the soil and trim the roots. Remove around 1/4 - 1/2 of the plants roots, most of the roots you remove should be from the underside of the tree. Remove any large bulky roots heading down http://dupuich.smugmug.com/Bonsai/Development/Japanese-Maple-Grove/i-6Bd9qVc/0/S/DSC_0052-S.jpg, remove any spinning roots, remove crossing roots, remove any thick roots that do not have any feeder root growth attached to them. Do not apply cut paste in the root system!

#3 Comb out the roots. After you've removed the tree from the pot remove as much of the nursery soil as you can. A root hook will work but can be aggressive and will tear a large portion of the roots. Use a chopstick for sensitive areas as it's less aggressive but will still allow you to loosen the soil. http://www.telfarms.com/img/shimp_roots.JPG http://www.gsbf-bonsai.org/hanfordbonsaisociety/fig.11.JPG

Start at the top and remove all moss. Next move to underneath the tree. Follow this by combing out the sides of the root ball. Finally gently work out the nebari. Once the entire root ball has been removed lay the tree on a flat surface and comb away from the trunk to spread the nebari.

#4 Soak the trees root ball. This step is not necessary but i've found it helps in transplanting. Use a Vitamin B and Mycorrhizia solution for about 15 minutes to stimulate root growth. I use "Roots and Great white."

#5 Prepare the pot: Wash the pot, wire in screens, add a grounding wire or two to secure the tree.

#6 Drainage layer: Put a layer of very fast draining soil at the bottom of your pot follow that by a layer of your normal soil mix.

#7 Place your tree. Make sure you have the position right before applying any soil. Push down gently on the root ball and nestle the tree into place.

#8 Fill the pot with soil and tie the tree down. Work the roots with a chopstick to get the soil into all the crevices. Tighten down the grounding wire with pliers securing the tree. Shake the chopstick back and forth with your wrist like seen in this video at 9:21 to get soil into hard to reach spots. http://www.youtube.com/watch?v=9OhuBvfJ8Xw This is a great video to watch, the bonsai they repot are quite established but the techniques are similar.

#9 Knock the pot. Using the handle of a hammer or similar rubber coated metal knock the pot several times on all sides to allow any air pockets to fill with soil particles. You can also tap the pot on the ground but i find the hammer technique to be much safer.

#10 Water the tree for a few minutes till the water drains more clearly out the bottom. If you are using lava rock this will be very apparent!

#11 Place the tree back in a mildly sunny spot till you see growth. Once you see renewed growth move it to a spot that suits how the particular tree prefers to grow.

#12 For deciduous trees you removed a large portion of roots from it can be helpful to remove some branches. You do not have to do this ESP if you repotted at the right time when the buds were just about to open but it can help. If you removed half of the roots it would be good to remove 1/4 or more of the branches. For evergreens it's better to leave all candles and top growth till the tree shows signs of renewed vigor. On pines ESP do not cut candles on repotted trees that don't show signs of growth till the fall.

If I missed anything please post below! Hope this helps.

 

[Poink88]

Great thread. Thank you.

For #1 & #2. If the pot have an inward curve or lip (I personally avoid this pot style if possible) You might have to use a knife or sickle to trim the roots at the edges to slip out a root bound tree. I use an old bread knife and it works very well trimming the root ball walls of nursery trees before I comb them out.

For #2. If you chop a major root on a nursery tree try to envision the final pot size and make sure it will work properly factoring the new root growth. I also use powder rooting hormone on these large root chops after the soak (step #4).

For #8 & #9. I find that filling the pot a scoop (or thin layer) at a time and using the chopstick to fill the crevices to be most effective (esp since I use deeper training pots still). Knocking, tapping and shaking the pot after, sometimes doesn't fill the crevices as well as we'd hope.

For #10. I usually use some of the soaking solution used at #4 to water the newly transplanted tree. I do this AFTER the major soaking have drained out. Note that the soaking also help fill the crevices with soil (if there are still any) so it is very important.

For #11. Factor draft as well. Windy locations can dry your plants fast so avoid such locations if possible or provide your tree added protection.

For #12. The goal is reduce transpiration so you can cut branches OR just remove some old leaves. Usually cutting branches is best if it is needed to make the tree more compact anyway.

 

[Beng]

Great thread. Thank you.

For #1 & #2. If the pot have an inward curve or lip (I personally avoid this pot style if possible) You might have to use a knife or sickle to trim the roots at the edges to slip out a root bound tree. I use an old bread knife and it works very well trimming the root ball walls of nursery trees before I comb them out.

For #2. If you chop a major root on a nursery tree try to envision the final pot size and make sure it will work properly factoring the new root growth. I also use powder rooting hormone on these large root chops after the soak (step #4).

For #8 & #9. I find that filling the pot a scoop (or thin layer) at a time and using the chopstick to fill the crevices to be most effective (esp since I use deeper training pots still). Knocking, tapping and shaking the pot after, sometimes doesn't fill the crevices as well as we'd hope.

For #10. I usually use some of the soaking solution used at #4 to water the newly transplanted tree. I do this AFTER the major soaking have drained out. Note that the soaking also help fill the crevices with soil (if there are still any) so it is very important.

For #11. Factor draft as well. Windy locations can dry your plants fast so avoid such locations if possible or provide your tree added protection.

For #12. The goal is reduce transpiration so you can cut branches OR just remove some old leaves. Usually cutting branches is best if it is needed to make the tree more compact anyway.

Used to use rooting hormone on large cuts but stopped as I wasn't sure it did anything the vitamin b soak didn't already do.

This year I put a black pine I've been growing in a pot with a lip curved in. It's a semi cascade that has a odd pigeons breast bulge from where i folded it over on itself years ago one Horst Heinzlreiters strange egg pots (kind of like this one http://www.hhpots.com/bei2618.html ) fit its oddness perfectly... I know I'm gonna be kicking myself in a few years. Will probably repot it in 2 years rather then 3 so I don't have to damage the pot getting it out.

 

[Poink88]

Used to use rooting hormone on large cuts but stopped as I wasn't sure it did anything the vitamin b soak didn't already do.

This year I put a black pine I've been growing for a long time in a pot with a lip curved in. It's a semi cascade that has a odd pigeons breast bulge from where i folded it over on itself years ago one Horst Heinzlreiters strange egg pots (kind of like this one http://www.hhpots.com/bei2618.html ) fit its oddness perfectly... I know I'm gonna be kicking myself in a few years. Will probably repot it in 2 years rather then 3 so I don't have to damage the pot getting it out.

Ever considered putting fillers inside to make the wall vertical? I know you will loose soil volume and space but it is an option I've been considering if I ever find a pot I cannot go without. Maybe use a sturdy foam insert...or even a spray foam then trim.

 

[Beng]

Ever considered putting fillers inside to make the wall vertical? I know you will loose soil volume and space but it is an option I've been considering if I ever find a pot I cannot go without. Maybe use a sturdy foam insert...or even a spray foam then trim.

I potted a cork oak on top of a flipped upside down azalea pot to keep the nebari flat in spring 2012. Then potted that pot and tree inside a larger pot and filled with bonsai soil. This was my first time trying this I will repot it again in spring 2014. I did this as the roots kept trying to grow down with enthusiasm rather then radially ramification.

 

[Poink88]

I potted a cork oak on top of a flipped upside down azalea pot to keep the nebari flat in spring 2012. Then potted that pot and tree inside a larger pot and filled with bonsai soil. This was my first time trying this I will repot it again in spring 2014. I did this as the roots kept trying to grow down with enthusiasm rather then radially ramification.

I have a few trident seedling I planted on top of a plastic sheet. I figured all the talk about using tiles is great but why use tiles when you can use a plastic sheet (HDPE) which is much easier to handle, won't rot, and can't be penetrated by roots. Much easier to remove too later...esp if you are planting in the ground (nothing to break when digging it out).

 

[Beng]

I have a few trident seedling I planted on top of a plastic sheet. I figured all the talk about using tiles is great but why use tiles when you can use a plastic sheet (HDPE) which is much easier to handle, won't rot, and can't be penetrated by roots. Much easier to remove too later...esp if you are planting in the ground (nothing to break when digging it out).

Whats HDPE?

 

[Poink88]

Whats HDPE?

High Density Polyethylene. A very durable plastic...same as the ones they use on soda bottles.