Gardenia has very exacting growth requirements and numerous problems develop due to an unfavorable environment. Grow gardenia in sun during the winter and partial shade in summer. Use an acid soil with a pH between 5 and 6. Keep the soil moist and use an acidifying fertilizer twice monthly from midwinter to early autumn.
Proper temperatures are necessary to force gardenia into bloom.
No flower buds set at night temperatures above 65 degrees. Keep small plants growing by providing night temperatures above 65 degrees. Night temperature above 65 degrees causes drop of buds already formed. Ideal forcing temperatures are 65 to 70 degrees during the day and 60 to 62 degrees at night. The flowering response requires 14 hour nights.