Can Gardenias Tolerate Heavy Rainfall?

Water

• Regular watering -- about 1 inch per week and more often during hot, dry periods -- keeps gardenia flowers and greenery from wilting. Stream the water directly into the ground to keep leaves and flowers dry. Because plants lose moisture through their foliage, maintaining a regular watering schedule is important. Too much water -- or the lack of it -- may lead to flower bud drop, especially on a heavily blooming shrub. In periods of drought or limited rainfall, dry soil may lead to shrinking and cracking of the shrub’s root system.

Rain

• Gardenia root systems damaged by heavy rainfall may kill the plant but you can install concrete or plastic drainage tubes, also called “tiles,” to lead excess moisture away from the shrubbery bed. You can also determine how much water a particular soil holds or drains by its texture or type, advises Washington State University Extension. For example, adding 1 inch of water to loamy soil moves about 6 to 10 inches into the foundation. In clay soil, 1 inch of water settles down about 4 to 5 inches under the surface.

Environment

• Gardenias prefer full sunlight but they grow well in partial shade if there are no tree roots nearby. Depending on growing environment, soil must be moist and acidic with pH of 5.0 to 5.5; anything above 6.0 may indicate an iron deficiency. You can test the soil prior to planting gardenias and then add organic materials such as peat moss, manure or compost to keep nutrients into the soil. Shrubs may be grown in containers but transplanting often damages root systems. Gardenias can tolerate occasional frosts down to 20 degrees Fahrenheit.

Planting

• Plant gardenia bushes in the spring or fall in a permanent location; shrubs do not transplant easily once root systems are set firmly in the ground. When setting the plant in its hole, the top of the root ball should be even with, or slightly above, the ground. The size of the hole depends on the size of the plant; however, the opening must be large enough to fill soil around the shrub’s trunk stems. Add water and then fill the hole with soil. Place a 2- or 3-inch layer of mulch around the base of the shrub. Water the gardenia plant two times a week for six weeks.

Care

• Feeding gardenias in March and June with chemical mixes, blood meal or fish emulsion helps shrubs produce healthy flowers. Fertilizing in the fall spurs new growth, but because gardenias are cold-sensitive evergreens, winter temperatures below 15 degrees Fahrenheit can kill them to the ground. Springtime feedings encourage plants to reemerge. Prune gardenia bushes after flowers have faded in the summer.