Mistakes To Avoid If You Want Healthy Gardenias In The Garden

Mistakes To Avoid If You Want Healthy Gardenias In The Garden

Gardenias are a popular plant in the Southern United States. They have a sweet aroma and beautiful, white flowers that contrast nicely with their green leaves. However, they require a lot of attention to grow properly. Overwatering, lack of sunlight, and poor nutrition can all damage the plant, causing it to grow poorly or even die.

Gardenias prefer soil with a pH between 5 and 6.5, so if your soil is too alkaline, you may need to plant them in containers. Gardenias have shallow roots and need plenty of space to grow, so be sure to plant them in a location where they won’t be disturbed. If you make a mistake, raised beds can help you correct it.

Overwatering and poor drainage are major slip-ups

brown gardenia leaf

Bhupinder Bagga/Shutterstock

Acing the acidity test isn’t sufficient to coax your gardenias into displaying their ornamental beauty; balancing their relationship with water is a must, too. The evergreen shrubs enjoy moist soils, but abhor drenched feet. Excessive watering can cause the green, unripe buds to drop off prematurely, leading to a poor show during flowering. Fungal diseases like root rot, powdery mildew, and cankers are a bother, as they thrive in wet roots. To stave them away, maintain the right irrigation schedule and ensure adequate drainage.

Without rainfall, soak gardenias weekly in 1 inch of water — use even more water during drought. If unsure of when you should water next, conduct a finger test, checking that the top inch isn’t dry to the touch at any time between soakings. While at it, avoid getting water over the foliage, lest it develop leaf spot, a vicious bacterial disease that covers the leaves in circular, tan spots. At the same time, avoid using salt-rich or reclaimed water to achieve the healthiest growth. Instead of cultivation, improve drainage by mulching plants with compost, bark, pine needles, and other organic matter, going at least 2 to 3 inches deep.

Fall fertilization, insufficient sunlight, and poor pruning practices are gardenia no-nos

Pruning gardenia


Mulching doesn’t discount the need for fertilization, given these flowering plants’ propensity to suffer iron deficiencies, causing yellowing shrubbery. Treating them to chelated iron becomes a requisite, in addition to routinely applying a slow-release, balanced azalea fertilizer at least two to three times a year. Just be sure to avoid fall fertilization, as it stimulates new growth in overwintering gardenias, exposing them to winter injury. That being said, given their tropical lineage, gardenia plants enjoy their fair share of sunbathing. So, don’t make the mistake of placing them in shaded spots unless you want to be stuck with small blooms. Instead, keep the multi-stemmed shrubs in full or partially sun-lit areas.

However, gardeners living in USDA zones 8 and above must provide sun protection during the midday highs to prevent the plants from scorching under intense heat. In their zest for higher spring blooms, many erroneously indulge in hard pruning practices during the fall, which doesn’t bode well for your broadleaf beauties. Although gardenias can be shaped throughout flowering, you must wait for the last blooms to wither out (mid-summer) before carrying out any major pruning. While the schedules will vary depending on the growth zones, pruning after October is generally looked down upon because the perennials already support new buds that will eventually bloom next year. Moreover, removing damaged branches improves air circulation, keeping powdery mildew and pests at bay.

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Dr Heidi Parkes

By Dr Heidi Parkes

Senior Information Extension Officer QLD Dept of Agriculture & Fisheries.