Transferring or transplanting gardenia shrubs is not a difficult task, but for the move to be successful long term the new location needs to provide the basic cultural conditions gardenias require. Gardenias are most commonly grown in ground soil but can also be cultivated in containers, which is necessary in cooler climes when the plants need to overwinter indoors for protection from cold and wind.
Prepare the planting bed where the gardenia will reside so that the surrounding soil is easy draining, loose, light and rich in organic material. Improve average quality ground soil or potting mix with several lbs. of compost and/or aged livestock manure. Till the planting area to a depth of at least half again the depth of the gardenia plant root mass so that the soil is light and new roots can easily penetrate it.
Adjust the pH of the planting soil to make it acidic in keeping with gardenias' needs between 5.0 and 6.5 pH. Till ground sulfur into the planting soil to lower the pH level and increase the localized acidity. Conduct a soil test if in doubt of the soil makeup and amend according to the product label to bring the soil into the desired range.
Excavate a planting hole twice the diameter of the gardenia root mass and a few inches deeper. Fill the bottom of the hole with a few inches of the loose and amended soil.
Tip the gardenia pot on its side and slide the plant out of the pot, keeping the root mass and surrounding soil intact as much as possible. Set the gardenia in the hole and add or subtract soil beneath the root mass so that the top of the root ball sits level with or just above the surrounding soil.
Back fill the loosened soil around the root mass, pausing halfway up to tamp the soil down lightly before filling in the rest of the hole.
Use the remaining soil to create a watering moat just outside the drip line of the shrub. Fill the moat with water, allowing it to percolate down into the soil before filling a second time. Water again two times each week for six weeks while the gardenia acclimates and establishes roots in the area.