Caliper Tree Planting Instructions
A caliper tree is described as a tree that has a stem diameter of 5cm (2”) or more when measured 15cm (6”) from the soil level or top of the bud union. Most caliper trees are dug; their roots are wrapped in burlap and placed in a large wire basket. Some caliper trees are also available in large plastic pots. This tree size, when planted needs very special care to survive the first growing season. Please read carefully before planting.
- Have at least .5 cu meter of good modified soil available for each tree that is to be planted.
- Carefully measure the diameter of the root ball and the depth of the root ball. This is important because if the root ball doesn’t fit it is difficult to correct once it is in the hole.
- Dig the hole at least 15 cm (6”) wider and deeper that the root ball.
- If the sub soil of the hole is hard pan clay, then it is advisable to dig the hole deeper and add about 10cm (4”) of washed rock to the bottom of the hole. This will allow some drainage as the clay will hold water which can cause the tree to drown.
- Add 15cm (6”) of soil to the bottom of the hole and pack it down.
- Add three generous handfuls of bone meal to the bottom of the hole. Add two more to the remaining soil.
- Do Not Add Water at this Point.
Planting the Tree
- Place the tree in the prepared hole.
- The top of the root ball must be level with the final grade.
- If a filter fabric and mulch is to be added, the top of the root ball can be 5cm (2”) below the final grade to accommodate the mulch.
- Do not allow any soil to be up on the mail stem above the root ball. Even 5cm (2”) up the stem will kill the tree.
- Now take the rest of the prepared soil and pack it around the root ball. Here is where you make sure that the is straight and the packed soil supports the tree in an up right position.
- Remove the burlap ties and bend the wire from the top of the root ball, but do not attempt to remove any burlap from the sides. It will rot away after the tree is planted.
- Finish planting by filling the side of the hole and the root ball with the prepared soil. Remember the top of the root ball is level with the finished grade.
- Firm the soil around the root ball using the handle of the shovel, this ensures that the soil is in close contact with the root ball (no air spaces).
- Make a mound of soil around the circumference of the root ball to form a bowl to accommodate the water that will be added.
- There must be a circle of open soil at least as large as the drip line of the tree with no lawn growing in the circle. Note that a lawn will absorb the 2.5 cm (1”) of water before any water penetrates into the root ball.
Staking the Tree
- Stake the tree with three support lines, one line on the windward side of the tree (northwest is the windward side).
- To avoid damaging the bark, put your rope or wire through a short length of hose, wrap it around the tree at 1 – 1.5 m. (3-4’) above the root ball.
- The three stakes must be pounded into the firm soil (outside the root ball) so that they will stop the root ball from moving during heavy winds.
- You are not trying to prevent the top portion of the tree from moving, only the root ball. If the root ball moves it breaks the tender roots that are trying to get established.
- The tree should be staked for one year after planting.
Watering the Tree
This is by far the most important process that you do for the tree in the first year of planting. Note most irrigation systems will not provide enough water for the newly planted root ball. You must water with a slow drip system that applies the water slowly over a long period of time to allow the root ball to completely absorb the all of the water. Hippo Bags are an ideal watering solution.
- A caliper tree needs 60 liters (15 gallons) of water at least twice a week and if the temperature is 25C or higher three times a week.
- Add the water close to the stem so that all of it drains through the root ball and not into the new soil surrounding it.
- Do not use a root feeder for at least one full year after planting as it will wash out the soil from the root ball and push the water to the surrounding soil not leaving any for the tree.
- If you are adding a filter fabric and mulch to the surface you must be careful that the tree does not get over watered. Remember the fabric and mulch are used to prevent evaporation so that the water you add stays in the root ball. A moisture meter is a great inexpensive tool. Push it into the soil near the trunk and check if it is time to water.