I spied some gardenias in my local garden centre this weekend, with their beautifully pristine flower heads and gorgeous scent. If the fragrance of flowers could be measured by a scentometer, gardenias would career off the charts. The perfume is intoxicating, a sultry mix of jasmine and bubblegum with a soft fruity note.

Gardenias are a much-loved garden plant but they have a reputation for being difficult to grow. That might be because they’re prone to yellowing leaves, or chlorosis as it’s called, which is caused by lack of chlorophyll. Why that happens could be any number of reasons, including poor drainage, damaged roots, high alkaline soils (gardenias like an acidic soil), wet or cold conditions, or nutrient deficiencies. Iron and magnesium deficiencies are the most common, but you need to look closely at the leaves to determine which deficiency your plant has. Iron deficiencies show up on the newer leaves, first turning pale green, then yellow. The veins themselves remain green. With a magnesium deficiency, the tip and edges of old leaves turn yellow first, leaving a green triangle at the base.

A small handful of epsom salts (magnesium sulfate) can be given to magnesium deficient plants, while iron chelates are ideal for iron-deficient plants. Although a regular feed with something like Burnets’ Sequestron, or a slow-release fertiliser with good N-P-K and micronutrients, should prevent deficiencies.

You might want to consider your water supply too. If you have hard water in your area, use rainwater instead of tapwater. Gardenias hate lime, and hard water is water that has high mineral content, mainly calcium – in the form of limestone and chalk – and magnesium ions.

Bottom image is from Karen Tran Florals.


  1. Your pictures are great! I love gardenias. Gardenias is an easy grown shrub here in Indonesia.

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