Sadly, gardenia augusta plants are cold hardy only in USDA hardiness zones 8 through 10. That leaves Ohio out when it comes to growing this temperamental beauty outdoors year round. And it isn't practical for many gardeners to plant gardenias outside, only to dig them up to bring indoors for the coldest months. Ohio can't offer ideal gardenia weather much of the time. But that's no reason for you to deprive yourself. Simply purchase a lovely nursery-grown specimen, and grow your gardenia indoors.
Move your gardenia plant to a clay pot with drainage holes immediately. Combine two parts good all-purpose potting soil and one part perlite or vermiculite to create your planting medium. Clay or terra cotta containers are best because they allow the planting medium to "breathe." They also facilitate the maximum amount of drainage for any plant.
Add about an inch of organic mulch to the top of your gardenia's potting soil. This will be helpful for keeping the roots moist, as well as for increasing the plant's humidity.
Pour a handful of coarse gravel into the drainage dish. Cover the gravel about halfway with water and place the gardenia on top of it. Don't allow the water in the dish to touch the pot. This setup is helpful in maintaining the gardenia's humidity, particularly during times when you're using artificial heating in your home.
Set your potted gardenia in the sunniest spot available in a warm room. A window with Southeastern exposure is the best choice. This plant needs all the bright light that you can possibly provide. Perfect temperature ranges for ideal gardenia performance are 65 to 73 degrees F during the day and 60 to 62 F at night.
Water your gardenia just enough to keep the soil surface evenly moist. Never allow the soil to become soggy or waterlogged, but don't allow the plant to dry out, either. When the surface dries out, poke your finger 2 inches deep into the soil. If it feels at all moist, don't water the gardenia.
Mist your indoor gardenia daily to add humidity to its environment. When conditions are particularly dry, you may need to mist two or three times each day.
Feed your indoor gardenia a good azalea food throughout the growing season according to the packaging instructions. Like rhododendrons and azaleas, gardenias love acid soil and prefer a pH between 5.0 and 6.0.
Use clean, sharp shears to snip out any stems that are dead or damaged at anytime. Otherwise, the indoor gardenia generally keeps a tidy shape and habit. Snip off the occasional stem that becomes a little too long for your taste to keep your gardenia attractive. Pinch out tips to promote bushiness during winter dormancy.