Why Are Your Gardenia Leaves Turning Yellow? We Have Answers

This could be a sign of a few different problems. Here's what to look for to figure out what's going on with your plant.

Why are your gardenia leaves turning yellow? There are a few possibilities. Because they're one of the prima donnas of the plant world, gardenias need everything to be just so, from the soil pH and drainage to the amount of water and fertilizer you give them. Luckily for them, their creamy white flowers have such a bewitching fragrance that they con us into meeting their persnickety needs, or at least trying very hard to keep them happy. So when some leaves on your gardenia start turning yellow, it can be worrisome.

Here, we'll look at possible reasons for this and suggest a few easy solutions. Soon enough, your fussy bloom will be green and gorgeous again, so it can produce more of those fantastic perfumed flowers that made you bring your gardenia home in the first place.

gardenia flowers
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Gardenia Growing Basics

If you live in the warmer regions of the country (USDA Zones 8-11), you can grow gardenias outdoors where they're easier to maintain. However, growing gardenias indoors during cold weather is where it gets tricky. The basic indoor gardenia needs are bright light, humidity, and regular watering. So try to put your plant in your sunniest window, set it on a saucer of rocks with water part way up the saucer to add humidity, and water it as soon as the top inch of soil feels dry.

Gardenia Leaves Turning Yellow

Naturally, some older leaves on gardenias may become yellow and drop off, particularly at the beginning of spring when the new leaves are on their way. This is normal, so there's no need to start worrying. But if too many older leaves are yellowing, your gardenia may be dying from root rot due to overwatering or poor soil drainage. Gently tip it out of its pot, or if it's outdoors, lightly dig away a little soil at the base of the plant. If the roots you see are brown and squishy, your plant isn't salvageable. If you find white, firm roots, it still has a chance.

If root rot doesn't appear to be the problem, the most likely reason for gardenia leaves turning yellow is a nutrient deficiency. Yellowing of many older leaves is often a sign of insufficient nitrogen or magnesium. Young gardenia leaves turning yellow is likely from low iron. All can be fixed by giving your gardenia a dose of an acidic nitrogen fertilizer containing micronutrients. Once your gardenia leaves are green again, use the fertilizer twice a month from early spring to late summer.

Because of their exacting care requirements, gardenias are among the trickier houseplants to grow and can be challenging as outdoor shrubs, too. Knowing what they require to look their best and correctly diagnosing any problems that do crop up will help you enjoy your plant for many years.

Frequently Asked Questions

  • Should yellow leaves be removed from gardenias?

    Most of the time (especially if the leaves are yellowing due to age), the discolored leaves will fall off on their own. If you think gardenia leaves turning yellow is a sign of something more serious (like fungus or rot), snip them off where the leaf meets the branch (being careful not to damage the wood), and dispose of the diseased leaves to prevent further infection. You can also prune off yellow leaves to encourage new growth and improve the look of the plant. Be careful of new buds, and try not to remove more than one-third of the shrub in an overall pruning. 

  • Why do gardenias need iron?

    Iron is an essential nutrient needed for the production of chlorophyll (the green pigment in leaves). Unfortunately, gardenias are fussy, acid-loving plants that prefer to grow in soil with a pH of 5.0 to 6.5—conditions that sometimes result in a lack of sufficient soluble iron for the plant to thrive.  

  • What's the easiest way to test soil pH?

    The easiest way to test your soil pH level is with a kit from your local garden or hardware store. Just collect samples of soil from different areas in your garden and follow the instructions on your kit to evaluate your samples. You’ll only need about a teaspoon of soil (from approximately 6 inches deep) in each area. 

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