Replant in ground or pond basket or BOTH??

[OneFeather]

I develop a lot of trees in the ground but don't use colanders or pond baskets. I can get really good root systems just by judicious root pruning. I know there are plenty who swear by baskets in ground but I can't see any advantages.
I would urge you to dig yearly to see how the roots are developing. Digging yearly makes sure no roots get over thick and it is still quite easy to cut through 1 year roots. After 2-3 years roots of some species can get thick and hard which makes digging a real chore. Regular root pruning also helps the roots ramify into lots of small feeder roots closer to the trunk which is needed for life in a small bonsai pot.
Pomegranate and citrus are often a bit slower so may benefit from 2 years at a time but be prepared to change depending on how they appear to be growing.
Trees will grow in soil but, depending what the soil is like, may do better with some additives to break up dense clays or really rocky soils. My native soils are quite good so I just add some compost and manures to help open the structure a bit. There should be no problem changing the roots to bonsai type mixes when they go into pots.

3-5 years is not overly optimistic to develop trunks in ground but be prepared for a few more years after that to grow the branches and final leaders in pots before finally calling them bonsai.

What additives would you advise? I'm gonna create a new post for my specific issue but I have clay heavy soil I mixed with some compost. What else can I add?

 

[dbonsaiw]

I would urge you to dig yearly to see how the roots are developing. Digging yearly makes sure no roots get over thick and it is still quite easy to cut through 1 year roots. After 2-3 years roots of some species can get thick and hard which makes digging a real chore. Regular root pruning also helps the roots ramify into lots of small feeder roots closer to the trunk which is needed for life in a small bonsai pot.

Is there any downside to repotting developing trees every year? I typically repot every year, but read somewhere this may weaken the tree over time. Thoughts?

 

[Shibui]

Is there any downside to repotting developing trees every year? I typically repot every year, but read somewhere this may weaken the tree over time. Thoughts?

Lots of people have opinions and love to air them publicly even those with little practical experience.
All I can say is that if yearly repotting weakens trees I have not yet seen it. Maybe the 4 or 5 years it takes me to develop a trunk is not enough time for problems to show but I suspect this weakening from root pruning is another bonsai myth.

What additives would you advise? I'm gonna create a new post for my specific issue but I have clay heavy soil I mixed with some compost. What else can I add?

Gypsum is often recommended to help break clay soils. The calcium in gypsum helps counteract the sodic nature of many clays without changing pH. Lime or dolomite can be used of the pH is low.
Sand and gravel are also used to help separate clay particles.
Compost or other organic matter can also help break up clays in the short term but typically need to be added year after year. It is possible to add organic matter to soils just by maintaining good surface mulches and relying on worms and soil life to take it down and incorporate into the soil below. Slow but reliable and much easier than digging it directly into sticky clay soils.

All the above can be used together or alternating depending what is available and affordable in your area and what area needs to be treated.
How much of anything will be needed will depend on the exact nature of the soil as there's many sorts of clay soils around the world and also what result you'd be happy with.

A quicker and less backbreaking alternative is to ignore the clay soil and garden above it. Plants will grow in raised garden beds or on mounds where roots can go down into the clay for water and nutrients but have good aeration above clay level. Probably higher initial cost depending on material availability and your skills but easier and more effective long term.

 

[dbonsaiw]

Lots of people have opinions and love to air them publicly even those with little practical experience.
All I can say is that if yearly repotting weakens trees I have not yet seen it. Maybe the 4 or 5 years it takes me to develop a trunk is not enough time for problems to show but I suspect this weakening from root pruning is another bonsai myth.

Many thanks

 

[Maiden69]

Is there any downside to repotting developing trees every year? I typically repot every year, but read somewhere this may weaken the tree over time. Thoughts?

I don't think that it would weaken the tree, but I do believe that it will slow down the development. The more roots you have the stronger the growth... with a caveat, the more feeder roots you have. If you let the roots go wild and run long you will probably end with not enough roots close to the trunk. This is one of the reasons many cut the roots around the trees when planted in the ground. I go around this by using Root Pouch, and replant every 2-3 years depending on how strong the roots of the tree grow. In the case of say a BC, a ficus, or a liquidambar which are notorious for super strong roots I would probably repot/replant every year or use an oversize bag and do two years.

This is why Root Pouch and colanders or any other air pruning device are so good for development. Because they prune the tip of the growing root forcing it to branch out and create a plethora of feeder roots close to the trunk. Draw back of the colander and air pruners is that they dry out too quick, which is why I chose to use the Root Pouch brand grey or black bags and place as pot-in-pot or in-ground.

I have noticed good growth on year one of the repot into a bag, colander, or ground, but year two and three are always better. Especially for trees in development where you want trunk and branch development. Once that is done, a pot that restrict the growth is the way to go to move into secondary/tertiary refinement.