Repotting Basics

Cardinal Rules of Transplanting

Timing - Selecting the perfect time to transplant is a supreme technique by itself. See Monthly Tasks for recommended times to repot.
Avoid heavy wiring either right before or after transplanting.
After heavy top pruning, do the same with the roots. The tree above the soil and under the soil must always be in balance.
Select the pot with great discretion. Study the harmony between plant and pot. See Selecting the Right Pot
Make sure the tree was watered the day before so it is well hydrated, but not so wet that it's like mud.
When loosening the soil around the root-ball, be very careful not to damage the root waterline (soft root system surfaces)
Always use sharp scissors to cut the roots. Never pull or tear off roots.
Once you are satisfied with the position, height and angle, securely fasten the tree in the pot.
The soil should be sifted to remove "fines" (dust) before use.
No air pockets (cavities) should remain in the soil after the repot. Use chop stick to remove.

Before repotting any tree it is important that the tree well be hydrated before working on it. During repotting you will break off many of the off fine roots and until they regrow, up to a week later, the tree won't be able to take up more water. After repotting you should keep the tree in the shade so you minimize water loss any the leaves.

After repotting it is important that the tree not move around or you risk of breaking off fine roots. Break enough and the tree will dry out and can die. So it is important to hold the tree firmly in the pot. During Kathy Shaner's demos at our club she often demonstrates her preferrred method to keep the tree from moving. She begins by laying two bamboo chopsticks across the roots to cushion the roots from the tie-down wires which will go on top of the chopsticks.

Kathy Shaner prefers bamboo chopsticks over the roots and then tie down wired over the chopsticks (top view)

Which Wire To Use

Some people like to use aluminum wire to tie their trees into the pot, but it is weaker than anodized copper. Aluminum wire is easier to break if you twist it too much, so you'd have to start over. On small trees this might not be an issue but once you get to trees that are larger than 8 to 12 inches tall, using copper will be less trouble in the long run.

For trees up to about 12 or 14 inches, 16-gauge copper wire is probably strong enough to hold the tree in. Larger trees will benefit from using 14-gauge or even 12-gauge for large trees - say around 36 inches tall. Actually, it's more the size and weight of the tree than it's height, but it's difficult to recommend wire size based on weight. For larger trees you'll use larger pots and need stronger wire to hold larger roots in place. Larger trees can sway more when wind hits them - and that's what you're trying to prevent. Swaying breaks off fine roots - the ones that gather moisture and nutrients to keep your tree healthy.

How Pot Design Affects Repotting

Different pot makers have used different holes in the bottom of the pot. Typically older pots used two holes and sometimes they are very small. These pots don't drain as well a pots with larger holes so the soil can remain wetter than is good for the roots. But they can be used.

As you see below we recommend twisting the wires together underneath the pot. That makes it less likely that the wires will shift as you are tying the wires together on top.

Two Holes At Ends of Pot

When you have a pot with smaller holes along the edge, use those to pass the tie down wires into the pot.

Pot with Two Holes (bottom view of pot)

Now turn the pot over and place a heap of soil in the pot about where your tree will be positioned. Now place your tree on top of the soil and wriggle it. This makes sure that there isn't an air pocket underneath the trunk. If you can see between the roots to the bottom of the pot either lift the tree and add more soil to the pot or add some soil from the top. Use a chopstick to push the soil beneath the roots.

Lay bamboo chopsticks on either side of the trunk so that they protect from the wires.

The tree, chopsticks and wires should look like this:

Pot with Two Holes (top view)

Steps

With your pilers, grab one wire from each end of the pot (Red and Blue in figure) and twist until the wire (1) is somewhat tight. When tightening wires pull them slightly towards you so you can prevent new twists of wire from overlapping earlier twists. Overlapping wires often break.
Repeat with the other two wires (2)
Now re-check that the tree is where you want it to be and then tighten both 1 and 2 until the wire is holding the tree tightly in the pot.
Add more soil on top and use a chopstick to settle soil as described in the section Settling Soil below.

Three-Hole Pots

When you have a pot with three holes, first twist two wires together near the middle so that they won't slip. Now run one leg out the left hole, one out the right hole and two out the middle hole - but spread to either side of the pot as shown below. To wire your tree into the pot see Multi-Point Tie Down later in this document.

Pot with Three Holes

Multiple Wire Holes

Newer pots typically have multiple smaller holes just for tie-down wires. The holes might be along side the long side of the pot like shown below. If the wires are in the corners you need to use a Multi-Point Tie Down

Newer Style Pot with Holes Specifically for Tie-Down Wires

When the holes placed as shown here you can tie your tree in like shown in Figure 3 - except turned 90 degrees. The two wires come up from bottom and tie together across bamboo chopsticks.

Multi-Point Tie Down

When you have multiple wires that are spaced around the pot you need to tie the wires together to form a ring.

Using Multiple Wires (Chopsticks left out for clarity)

Tie Red to Blue, leaving 2+ inches at end of Blue
Tie end of Blue to Green, leaving 2+ inches at end of Green
Tie end of Green to Orange, leaving 2+ inches at end of Orange
Loop a new wire (Purple) around Red and tighten it enough that it won't slip. Don't twist the Red wire of you may break it.
Tie end of Purple and Orange together and tighten until entire ring of wires holds the roots tightly.

As you tie Red to Blue to Green to Orange you want to make each connection as snug as possible. When the final wire is connected it will allow you to really tighten the ring. The ring should be large enough / far enough from the tree trunk to hold down the roots. If you've left each wire too loose you will wind up with a ring that is very small as you tighten the final wire and you won't be holding down the roots.

Settling Soil

Once the tree has been wired in you need to finish the process. If you just pour soil into the pot you will likely get air pockets - bubbles within the soil. Roots that aren't iin contact with soil will not be able to absorb moisture and nutrients and wil die - weaking your tree. The preferred method is to gently agitate the soil with a chopstick so that the air holes collapse. Also known as "chopsticking", this involves inserting a chopstick into every area of the soil and gently wiggling it. The motion will cause the air pockets to collapse, filling with soil. First, make sure there are no pockets underneath the trunk.

Fill Air Pockets Underneath Trunk

Now work the outer edge of the pot to make sure there are no air pockets there.

Wiggle Chopstick to Fill Air Pockets

Finish by compacting the soil - just press down on the top of the soil with your hand or a flat tool and wiggle slightly.

Now water - several times. This first watering is important because it helps the soil settle further. You need to water several times because soil components take time to go from dry to moist enough to sustain your tree.