Plants growing in the garden sometimes need to be put in large pots to shift locations or to move the plant indoors. Plants that are moved into pots will experience different degrees of transplant shock as roots are damaged and environmental conditions such as light and moisture levels change. In order to prepare an outdoor plant that was growing in the ground for a large pot, you need to follow certain procedures to minimize transplant shock. If possible, the plant should be removed from the garden during the winter or when the plant is dormant.
Choose a container that is 2 to 4 inches larger in diameter than the root base of the plant you are removing from the garden. Try to match the plant's root base with the size of the container by looking at the diameter of the main trunk of the plant. For every inch in diameter of the trunk of the tree or plant you will need to dig up a ball of earth containing the roots that is one foot in diameter. For example, a bush or tree with a one inch diameter trunk will need a root ball one foot in diameter to survive the transplanting process.
Water the plant by deeply soaking the roots a day or two before the plant will be removed from the garden and placed into the large container.
Take a shovel and push the blade straight down into the soil. Forming a circle around the plant at the correct diameter to cut the roots of the plant so the plant will fit in the large pot. For example, because the plant with a 1-inch diameter trunk needs a 1 foot root ball in diameter, you will need to begin digging and cutting roots in a circle 6 inches from the trunk.
Dig under the plant to cut the roots in order to move the plant. Carefully pull the plant from the ground after you have completed the digging process and lightly mist the root ball with water to keep the root ball damp, but not wet, while preparing the plant container. Soaking the root ball will make it very heavy to move.
Prepare the large plant container by putting a 1-inch layer of small gravel across the bottom to ensure drainage. Add a layer of potting soil. Lift the plant into the container and add potting soil around the edges of the root ball and across the top, firmly tamping down the potting soil and adding water to settle the potting soil around the roots. The plant should be planted at the same level it was planted in the ground. Add a one-inch layer of decorative mulch over the top of the potting soil in the pot to help retain moisture.