Mexican petunia plants are perennials that grow in USDA hardiness zones 7 to 9. They come in several varieties with either pink or purple flowers. Mexican petunias are resilient plants that can withstand transplanting. It is best to transplant perennial plants like Mexican petunias in the fall before their dormant season; however, you can transplant them anytime if necessary. It may just take a few days or a couple weeks for them to bounce back after transplanting.
Water your Mexican petunia plants the day before transplanting. The extra moisture will enable them to better weather any transplant shock.
Amend the soil in the new planting location, which should provide full sun or partial shade. The soil should be well draining, so if necessary, add a few inches of compost or peat moss to the planting site prior to digging and replanting.
Transplant in the evening when it is cooler, especially on hot days. This will give the petunias a chance to adjust to their new planting site before they experience the hot sun.
Water the plants one last time. Use a trowel and dig carefully several inches away from the base of your plants and at least 6 inches deep to clear most of the roots.
Replant the plants immediately. Keep the soil that is surrounding the roots when you dug them up and replant them as deep as they were previously planted. Pack down the soil firmly so there are no air pockets. Water again. Cover the area with a couple inches of mulch, especially if it is extremely hot.