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Gardenias can survive cold winter in southern New Jersey with a little care

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I love gardenias. Whenever I pass the hardy gardenia plants in the nursery, I have to stop to smell them. They are truly one of my favorite scents. I have a beautiful bloom on my kitchen table right now.

I had these fragrant, romantic flowers in my August wedding bouquet almost 50 years ago. When I stop to sniff the gardenia plants in the nursery, I often pick a few to add to the wedding bouquets or arrangements that I am making for customers. Most people do not realize that these hardy gardenias can be planted outside year round and they will bloom all summer. There are hardy and there are tender gardenias. The hardy will grow outside all year long and the tender must be taken inside. You can plant some hardy ones now so they will establish prior to winter.

Some winters, I have tender gardenia in my sunny bay window. We take them inside and they bloom for a while, but as the days get long, cold and dark, they often do not bloom much until the longer days of spring begin after Valentine’s Day. They love sun and do not mind being cool at night. They especially want to have long drinks of water with plant food in it all summer and again in spring as the days get longer. I also have a spoon or so of time-release osmocote plant food in each pot or around plants outdoors each spring. This is a plant, like azalea, that will benefit when you dump your coffee grounds all around it. 

In reading about gardenia, I found that they are related to the coffee plant. They are shiny evergreens and most grow in tropical places. There are a few, however, that will make it through the winter here in our USDA Zone 7 if they are planted in a somewhat protected site close to a wall and out of the wind. I have been reading a lot of online forums and discussion groups to see just how far north they have been grown outside and just what varieties do well. Many folks love their success with growing hardy gardenia outside all year long. With a somewhat protected site up along a house foundation, they seem to do well here in southern New Jersey.

Our son Joe has planted several outside. He seems to think that a good summer with adequate food and water, as well as a rich soil with a lot of humus in it and a site that is somewhat protected, will ensure success.

Sometimes a corner location with good morning sun that is protected by two walls helps these hardy perennials to survive a winter. Raking lots of leaves to almost cover the plant can also work wonders for winter protection. Last winter was cold for so long that some plants were damaged, but according to Joe, leave them in the ground and they often come back. He has some now sending up shoots. I just planted one along my walkway to the front door.  

You, too, can plant a hardy gardenia, but try to do so soon so they can establish good roots long before winter. Since they like acidic soil, I will mulch each with chopped leaves in fall. That will also help moderate the soil for winter. Because we have sandy soil, I have to be sure to never allow the  gardenia to dry out. 

In summary, hardy gardenias should be planted in well-conditioned soil containing compost. Avoid cultivating around the plants, because that may damage their shallow roots. Mulch the plant with triple-shredded root mulch  or chopped leaves to keep the soil moist, cool and weed-free. Feed the plants in spring with a time-release such as osmocote. Do not feed after July, as that might produce tender growth that will not be hardy in winter temperature. If the plant looks pale, yellowish-green, however, feed it now. I like a mild does of plant nutrient to restore plants to good health.

They seem to bloom best with moderate temperatures that drop down a bit in the evening. The ideal blooming temperature range is  65 to 85  degrees during the day and 60 to 65 degrees at night. Plants can be pruned as they finish a blooming cycle. If you want your plant to become bushier, pinch out the tips. Pinching will usually promote a heavier bloom the following year.  

Although there are said to be several hardy gardenia, here are a few that have made it through the winter for us when planted in a protected area: Gardenia Frostprof, Gardenia Daisy, Gardenia Chuck Hayes and Gardenia Variegata. All can also be grown in a large urn or pot out on a deck and then kept in a bright, sunny garage or unheated porch or cool greenhouse over the winter. I like gardenia so much that I always try to have several in sunny windows. Email garden questions to lorrainekiefer@gmail.com