Andersen Flat Modification for Bonsai purposes!

River's Edge

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Here is a suggestion for improving the function of Andersen Flats. The first change is applying wire on the bottom to hold the flat up if placed on a solid surface, thus allowing better drainage and air movement. The second is a set of holes drilled just above the base rim around the outside perimeter to improve drainage and air flow. I like the shape and depth have just had issues with drainage unless placed on a screen or gravel base.
The wire i chose was thicker aluminum, bent both ends to match outermost holes and using pliers twisted the end down inside. Three wires one on each side and one in the middle!
The last picture shows the location of the additional holes.IMG_0284.JPGIMG_0285.JPGIMG_0286.JPG
 

bwaynef

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I would think the holes that low on the sides would be superfluous with holes in the bottom that close to the ones you're adding.
 

River's Edge

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I would think the holes that low on the sides would be superfluous with holes in the bottom that close to the ones you're adding.
Possibly! I made those to assist when the flat gets set on very level, non porous surfaces before i raised the bottom with wire.
The good thing is it is just a suggestion! Sort of like speed limits;)
 

butlern

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Good suggestions, Frank.

Prior to placing the trees in my flats, I have been wiring lengths of (mostly dimensionally congruent) bamboo across the bottom to raise them enough allow for free drainage.

They eventually decay, but bamboo is pretty tough and light weight and they last long enough between root work activities (several years).

The only downside to my approach is if either the wire or plastic mesh happens to break, then the bamboo shoots are flopping all over the place and it's very hard to get them wired back into the screens on the bottom of the flat when it's filled with soil and weighted by a tree stump.

Keep the innovations coming!

Noah
 

Ohmy222

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They sell feet for them 4 for less than a dollar. I use four wooden blocks under them. Don’t fasten them down.
 

River's Edge

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Good suggestions, Frank.

Prior to placing the trees in my flats, I have been wiring lengths of (mostly dimensionally congruent) bamboo across the bottom to raise them enough allow for free drainage.

They eventually decay, but bamboo is pretty tough and light weight and they last long enough between root work activities (several years).

The only downside to my approach is if either the wire or plastic mesh happens to break, then the bamboo shoots are flopping all over the place and it's very hard to get them wired back into the screens on the bottom of the flat when it's filled with soil and weighted by a tree stump.

Keep the innovations coming!

Noah
Interesting, my first attempt involved wiring chop sticks on the bottom. They eventually rotted and loosened up as they shifted in the wire loops. Not tight enough and hard to fix after the plant was placed in the flat.
Was not convinced it was a good solution.
I think this heavier wire will do a better job for a longer period of time. I need to repot 84 JBP that have outgrown the wooden grow boxes i put them in two growing seasons ago. The flats add some extra area but are about the same depth to continue growing them on.
I am also using them for Tridents that have been in the grow boxes for two years. I place less soil mix in the flats for the maples. The wire legs may reduce the roots escaping with a bit of air pruning activity.
 

River's Edge

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They sell feet for them 4 for less than a dollar. I use four wooden blocks under them. Don’t fasten them down.
I tried the feet and did not like them, wooden blocks would work. For me though i am shifting trees pretty frequently, turning them, wiring, weeding etc. Moving and placeing feet would be an extra. it is different with the number of trees i work with in the nursery!
 

Arcto

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Good idea. I wonder if sloping the flat slightly as well as raising would improve the drainage more? I had the same issue with flats. I just laid a stick across the bench and propped one end of the flat on it.
 

River's Edge

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Good idea. I wonder if sloping the flat slightly as well as raising would improve the drainage more? I had the same issue with flats. I just laid a stick across the bench and propped one end of the flat on it.
That works well too, specially if the flats stay put more than mine do.
I have done that with a few on the bench.
 

butlern

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agree... the feet are good for about 6 minutes
!
 

River's Edge

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agree... the feet are good for about 6 minutes
!
The newer style deep propogation is very useful though. Nice overall size,
15 1/2 by 15 1/2 by 5 1/2 deep. Great for most grow out purposes.
 

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Brian Van Fleet

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I’ve used Anderson flats for 20 years and never found drainage to be an issue. In fact, a key advantage of the grid bottom is the ability to set the flat on the ground and allow roots to escape, while still maintaining a viable root ball inside the pot. It’s a good compromise to ground-growing if you don’t have a lot of space, but you definitely need to keep watering the flat to keep those roots healthy.

I always use tie-down wires, on Anderson flats too. On these, I run the tie down wires just to the outside of the 4 solid squares in the bottom, so when I tighten the wires, they’re not pulling against the grid, but against the solid part.
2AEF666F-E25A-44F7-B1E9-B4D66877FC0B.jpeg
Trident maple, Japanese Red Pine, Prunus Mume, Ilex Serrata:
652D698F-397B-4762-A922-DC9500B53FA7.jpegB9EEBF27-3A7D-406A-BEB1-1E111172B39F.jpeg0F44F42E-10FD-4FFA-9774-EDA8608326FB.jpegE5BAE373-5F7A-4368-A178-8C1A79F0423F.jpeg
 

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