How To Protect Gardenias In Winter

Look around any Southern garden and you'll spot gardenias: those evergreen shrubs with snowy white flowers that release their sweet perfume all summer. Gardenia's glossy leaves tough it out in high heat and dry weather, making it a great landscape choice for the Middle South down to the Tropical South. But gardenias can be sensitive to extended frosts and experience damage from very cold temperatures. Especially if you live on the edge of this shrub's growing range, follow these expert tips to protect your gardenias in winter.

How Cold-Hardy Are Gardenias?

Gardenias can be grown in USDA Plant Hardiness Zones 8-11, with a number of varieties cold hardy enough to survive in Zone 7. But the shrubs can suffer from winter damage when the temperature dips below 15°F. That means gardenias require extra winter protection in Zones 7 and 8, which occasionally experience a cold snap with sub-freezing temperatures. In Zone 7a, the thermometer can dip as low as 0°F on the coldest day in winter, while Zone 8b can get as chilly as 15°F.

You'll know your plant has suffered cold damage if the leaves turn brown or black and crisp. If most of the plant is damaged, you probably won't get to experience the heady scent of gardenia flowers next summer. But don't despair, because new growth can appear at ground level in the spring. With patience and care, you may once again enjoy the perfume of gardenias in future years.

Preparing Gardenias For Winter

You'll want to stop fertilizing gardenias at least two months before your first freeze. Fertilizing can lead to tender new growth that gets damaged in winter.

Refresh the mulch around your gardenias before winter so the roots are blanketed with a layer 2 to 3 inches thick. This will help the roots survive any deep freezes.

Winter Protection During Severe Weather

Keep an eye on the forecast for severe weather so you know when to jump into action. When you're expecting a cold snap, check the soil around your gardenias. If the soil is dry, water plants so that frigid weather doesn't zap the foliage. Don't overwater, though, which can lead to ice forming around the roots.

For extended cold spells, fully wrap gardenias with frost cloth, which you can order online or possibly find at the local garden center. If you're caught unprepared, just use an old sheet or blanket. Use something heavy like bricks or stones to anchor the cloth in place. Remove the cloth once temperatures warm enough for the plant to survive. You may need to remove the cloth during the day and replace it at night.

The thin stems can break from heavy snow or ice. You can protect smaller shrubs by placing a sturdy cardboard box over the plants until severe weather has passed.

Caring For Potted Gardenias In Winter

Container-grown plants are more susceptible to freezes because the roots are unprotected. During cold spells, temporarily move your containers to a sheltered spot that will stay warmer, like a garage. You can also bury containers underground for the entire winter and add a thick layer of leaves or mulch around the base of the plant. Small pots can be brought indoors for winter and grown as a houseplant until spring.

If you prefer to leave your pots in place outdoors, heap an insulating pile of leaves or straw around the pot all the way to the top edge. You can use a tomato cage to hold the insulation in place.

Indoor Winter Care For Gardenias

If you plan to bring your gardenia indoors for winter, start preparing the plant in fall. Prune off any diseased or dead branches. Move the pot to a sheltered spot in the shade and check it regularly for pests. Spray the foliage with insecticidal soap, making sure to soak the tops and bottoms of all leaves. You don't want to infest any other houseplants, so this may require more than one treatment.

Move the plant indoors as soon as temperatures begin to drop down into the 50s at night (waiting until freezing weather will be too much of a shock). Place the gardenia in a south-facing window and keep soil lightly moist. Don't prune or fertilize the plant before spring.

Homes tend to be very dry in winter. Gardenias like humidity, so place your pot on a tray of wet pebbles or mist the leaves lightly in the mornings.

When temperatures start to warm in spring, begin to harden off the plant by placing it in a shady spot during the daytime. Gradually increase exposure to sunlight and cold temperatures over a couple of weeks before leaving the container outdoors.

Dealing With Cold Damage

Wait to prune damaged stems and foliage until spring when temperatures are above freezing. This prevents further damage and gives your gardenia a chance to sprout new buds before you start cutting. Prune off brittle brown stems, but leave anything pliable in place for several weeks in case new growth appears. Apply slow-release fertilizer for acid-loving plants and keep soil lightly moist to encourage your gardenia's recovery.

If your shrub died back to the ground, wait to see if it sprouts new shoots before tossing it out. You'll know by summer if your gardenia survived. Let shoots grow to at least 6 inches before you do any pruning or shaping. With any luck, you'll enjoy new blooms on your gardenia next year.