Posted by Brent Wilson on 11/1/2017 to FAQ (Frequently Asked Questions)
Desired for their wonderfully fragrant flowers and lustrous evergreen foliage why wouldn't anyone want to grow a gardenia indoors...especially those who live and garden in climates where they are not reliably cold hardy outdoors. With the exception of a few gardenia varieties that are cold hardy to USDA Zone 7 most are not cold hardy above USDA Zone 8. Find your USDA Zone here.
So, is it possible to grow Gardenia plants indoors? Yes! That said, they aren't the easiest plant to grow as a house plant...but with the proper care and attention you can do it. Below are some helpful tips that will help in your success.
Soil pH is very important!
Soil pH is one of if not the most important factors in successfully growing a gardenia plant indoors. Gardenias prefer a much more acidic soil than most other plants; between 4.5 to 6.0 on the pH scale. Gardenia growing in an alkaline soil will often develop chlorosis (yellowing of leaves) and won't bloom. Maintaining acid soil conditions in a pot or other container requires more attention than plants growing outdoors in the ground. So it's a good idea to occasionally test soil pH and adjust if necessary to maintain an acid soil.
When growing outdoors, gardenias appreciate some bright light, but not too much. Four hours of sun per day is suggested for best blooms. Morning sun with afternoon shade is recommended as they don't like direct afternoon sunlight. The same will apply when growing gardenias indoors. An east facing room that allows the morning sun in but is shady in the afternoon is ideal. A south facing room is okay but just make sure the plant is positioned so that it doesn't receive the hot afternoon sun rays. During the winter months or other times of year when there might be insufficient light you might have to reposition the plant or use artificial light source to supplement.
Humidity is important as well. Gardenias prefer a relative humidity around 50 percent. This might be normal during summer but can be a challenge during winter. You can use a hygrometer to monitor humidity. There are several ways you can increase the humidity around your plants. Though not necessary to do, one way is to mist plants daily with water during dry periods. You can also place the potted plant on a saucer filled with gravel or pea pebbles adding water as needed. As the water evaporates it increases the humidity around the plant. Perhaps the easiest thing to do is place a humidifier near your plants.
Whether growing in the ground or in pots gardenias prefer a moist but well-drained soil, not constantly soggy, which can cause root disease. On the other hand, dry soil can effect bloom and even cause buds to drop.
When growing indoors gardenias prefer consistent temperatures. Cool nights and warm days trigger bud development, so your gardenias growing indoors may bloom at different times than those growing outdoors. Gardenias produce the most flower buds when nighttime temperatures are between 60 and 66 degrees F and when daytime temperatures are not exceeding 75 degrees, which is usually not a concern indoors.
Gardenias appreciate fertilizer for optimum growth and flowering. Feed gardenias growing in pots with a well-balanced water soluble plant food such as 20-20-20 as directed on the product label 3 or 4 times a year. Avoid excess fertilizer, which can cause plant damaging salt buildup in the soil and root dehydration. If gardenia leaves become yellow (chlorotic), an iron deficiency can be corrected by acidifying the soil as mentioned above.
Hope this info was helpful.
Plant Long & Prosper!
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