The Hibiscus genus contains hundreds of gorgeous plants with large, showy flowers that only last for a few days. Applying fertilizer at the right time helps you enjoy a beautiful bounty of hibiscus flowers throughout the season. In this article, I’ll share my experience of fertilizing hibiscus for optimal plant health and maximum blooms each season.
When to Fertilize Hibiscus Plants
The best time to fertilize your hibiscus plants depends on what type of fertilizer you’re using. If you’re using slow-release fertilizers, apply four doses each year throughout the season. Apply the first dose in early spring, followed by a second dose once the first round of flowers finishes. Add a third dose in mid-summer and the final dose in early winter.
If you’re using liquid fertilizer, apply a diluted dose every two weeks throughout the growing season. In fall and winter, reduce the frequency to once every four weeks for tropical hibiscus. Hardy hibiscus goes dormant during the winter, so stop feeding them once they lose their leaves.
The Role of Fertilizer in Plant Health, Growth, and Development
Plants need nutrients to produce new tissues, which form leaves and flower buds. Plants obtain nutrients from the soil, but these nutrients get depleted over time. Fertilizer replenishes the nutrients in the soil, helping plants continue to develop and grow throughout the season.
All plants require four types of nutrients;
- Structural macronutrients – Carbon (C), Hydrogen (H), Oxygen (O)
- Primary macronutrients – Nitrogen (N), Phosphorus (P), Potassium (K)
- Secondary macronutrients – Calcium (Ca), Magnesium (Mg), Sulfur (S)
- Micronutrients – Copper (Cu), Iron (Fe), Manganese (Mn), Zinc (Zn)
The structural macronutrients, carbon, hydrogen, and oxygen, come from water and the surrounding air. During photosynthesis, these nutrients are used to produce glucose. This important sugar allows plants to manufacture cellulose, the building block of plant tissue.
Fertilizer is primarily used to replenish the three primary macronutrients in the soil. Nitrogen helps produce bushy foliage, phosphorus helps produce flowers, and potassium helps improve overall health and fight off diseases. All fertilizers have an NPK ratio that reflects how much nitrogen, phosphorus, and potassium each dose contains.
Fertilizers may also contain secondary macronutrients like calcium or magnesium and micronutrients like iron and zinc.
Types of Fertilizers
Most fertilizers are divided into two types; organic and synthetic fertilizers. Organic fertilizers must be broken down by organisms within the soil before plants can absorb the nutrients. Synthetic fertilizers don’t need to be broken down, allowing plants to access nutrients instantly.
Fertilizers are typically sold either as liquid fertilizers or slow-release granules. Liquid fertilizers must be diluted before being applied, while slow-release granules are mixed into the soil.
Which Type of Fertilizer is Best for Hibiscus Plants?
Hibiscus plants are divided into two types; hardy hibiscus and tropical hibiscus. While both types of hibiscus thrive in different climates, they have similar fertilizer requirements. You can use both liquid fertilizers and slow-release granules for hibiscus plants.
To grow at their best, hibiscus plants need high levels of nitrogen, low levels of phosphorus, and medium amounts of potassium. Use fertilizers with NPK ratios similar to 12-4-8 or 7-1-2.
How to Fertilize Hibiscus Plants
If fertilizer is misapplied, it can damage your hibiscus plants. Here’s a quick guide to fertilizing hibiscus:
- If you’re using liquid fertilizer, lightly water the soil around your hibiscus. Then dilute the recommended dose of fertilizer according to the packet instructions.
- Apply the liquid fertilizer to the soil every two weeks, taking care not to splash any on the leaves or flowers.
- If you’re using slow-release granules, simply mix them into the soil four times a year.
- Thoroughly water the soil to activate the granules.
Hibiscus Fertilizer Needs FAQs:
When Should You Fertilize Hibiscus?
If you’re using liquid fertilizer, feed hibiscus plants once every two weeks throughout the growing season. If you’re using slow-release fertilizers, feed your hibiscus four times a year.
Does Hibiscus Need Special Fertilizer?
Hibiscus plants don’t require any special fertilizer. Both liquid fertilizers and slow-release granules work well. Use fertilizers that provide high amounts of nitrogen (N), low amounts of phosphorus (P), and medium amounts of potassium (K).
Should I Use Miracle-Gro on My Hibiscus?
Some Miracle-Gro products are suitable for hibiscus plants. Choose products that have a suitable NPK ratio for hibiscus and apply each dose according to the packet instructions.
Fertilize hibiscus plants every two weeks during the growing season if you’re using liquid fertilizer. Apply slow-release fertilizers four times a year. Use fertilizers that provide high levels of nitrogen, low amounts of phosphorus, and medium levels of potassium.
For more, see our in-depth guide to troubleshooting non-flowering hibiscus plants, common causes of yellow leaves on hibiscus, and 32 amazing uses and benefits of hibiscus plants.
Edd is a budding content writer and gardener living in the United Kingdom. He has a bachelor's degree in Creative and Professional Writing and has written for several gardening publications online. He is passionate about nature and sustainability with a focus on gardening and wildlife.
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