Fertilizer for Gardenias

Jeanne Grunert
Unhappy gardenia

Fertilizer provides gardenias with important nutrients to boost plant growth and flowering. However, it takes the right kind of fertilizer applied at the proper time to get the job done.

Fertilize Your Gardenias

Gardenias love acid-rich soils, and the soil pH should be between 5 and 6, with an ideal of 5.5. Before applying fertilizer, have the soil pH tested. If the pH is higher and on the alkaline side, or above 7, a soil acidifier helps bring it back to the level gardenias love.

Signs that your gardenia plant may need fertilizer include:

  • Yellow leaves: Leaf development depends on nitrogen, and a lack of available nitrogen within the soil may contribute to yellow leaves. Without healthy leaves, plants cannot make their food through photosynthesis.
  • New growth stunted: This is another sign the plant needs more nitrogen to support growth.
  • No buds or flowers: When nutrients in the soil are scarce, plants enter survival mode, focusing on basic survival needs like root development. Fertilizing gardenias restores this balance and encourages flower development again.

When to Fertilize Gardenias

Gardenias need fertilizer during their growth cycle to support development and fuel growth and flowering. Flowering is part of the reproductive cycle of plants. Plants expend a great deal of energy creating baby plants! Fueling growth by fertilizing gardenias adds valuable nutrients back into the soil which are used during blooming cycles.

  • Prime time for fertilizing gardenias is April through November for the vast majority of gardeners.
  • Gardeners in southern Florida and similar garden zones should fertilize anytime between March and October.
  • Space the application of fertilizer out in two to four week intervals. It is better to err on the side of caution and fertilize less frequently than more frequently, because too much fertilizer can burn the gardenia's roots.

What to Use

Since gardenias are acid-loving plants, you will need a fertilizer created especially for gardenias and similar plants.

Gardenias in bloom

Scotts Miracle Grow MirAcid is perhaps the most popular brand of fertilizer for gardenias. MirAcid contains a ratio balance of 30-10-10. These numbers represent the ratio of nitrogen (N), phosphorus (P) and potassium (K) contained in the mix. MirAcid also includes copper, manganese and other trace elements, which are great for leaf and flower development. MirAcid fertilizer contains inorganic chemicals, so if organic gardening techniques are important to you, you may want to try one of the many organic fertilizers on the market.

Fox Farm Grow Big fertilizer contains a balance of 6-4-4, and it's readily available online or in your local garden center. It provides a steady, slow release of organic materials into the soil with an emphasis on nitrogen.

Yum Yum Mix is another organic fertilizer which contains a ratio of 2-1-1. Created by Sante Fe landscape design expert Donna Bronner, Yum Yum Mix is especially good for nutrient-poor alkaline soils, such as those found in and around New Mexico and other southwestern states. It includes a rich blend of alfalfa meal, cottonseed meal, rock phosphate and other goodies that not only provide plants with nutrients, they also nurture beneficial soil microorganisms.

How to Fertilize Gardenias

In general, gardenia fertilizers come as powders, pellets or liquids. They're typically mixed with water in a ratio listed on the package direction. Depending on the fertilizer you've chosen, you'll either mix the fertilizer directly into the soil or water it into the soil around the plant.

Avoid sprinkling fertilizer on the leaves because it may disfigure them. A common mistake among neophyte gardeners is to sprinkle water or fertilizer on the leaves, instead of the soil, in the mistaken belief that the leaves take up nutrients. It's the gardenia's roots that need the nutrients, so be sure to get as much as you can into the soil.

Apply pellet fertilizers by mixing gently into the soil around the plant in the recommended amount. Powders and liquid concentrates typically require mixing with water before applying to the soil.

gardenia

Success with Gardenias

Gardenias may not be the easiest plants you can grow, but they are certainly worth the effort once you smell those heavenly flowers. Always read and follow the package directions carefully for whichever fertilize your use, and your gardenias will thank you with an abundance of blossoms.

Fertilizer for Gardenias