Lemon myrtles are beautiful evergreen trees with lemon-scented leaves. These trees produce masses of fantastic white flowers during the summer. In this article, I’ll share my experience on when and how to fertilize lemon myrtle.
Which Type of Fertilizer is Best for Lemon Myrtles?
Lemon myrtle trees (Backhousia citriodora) need well-draining soils that retain some moisture. The soil needs to contain plenty of nutrients to fuel flower production. Lemon myrtles also prefer slightly acidic to neutral soils with pH levels between 5.5 and 6.5.
Adding organic matter, such as compost, helps enrich the soil around your lemon myrtle. Lemon myrtles only need fertilizing once a year, so give them a slow-release fertilizer. This allows your lemon myrtle to access nutrients for most of the year, whether from the soil or fertilizer.
Choose nitrogen-rich fertilizers if you want a bumper crop of lemon myrtle leaves to use in the kitchen. This promotes the growth of bushy foliage rather than flowers. If you want lots of blooms, use balanced fertilizers or ones that are higher in phosphorus.
When to Fertilize Lemon Myrtles
Fertilize lemon myrtles once a year in the fall, just after the flowers finish. Use slow-release fertilizers to give your lemon myrtle plenty of nutrients throughout the winter. There will still be plenty of nutrients left in the spring for your tree to use to produce new growth.
If you’re using lemon myrtle leaves for cooking, keep in mind that fertilizers may affect the taste of the leaves. To be on the safe side, avoid picking lemon myrtle leaves for a few days after fertilizing.
How to Fertilize Lemon Myrtles
Here’s a quick guide explaining how to fertilize lemon myrtle trees:
- Fertilize your lemon myrtle in the fall once the flowers have finished.
- Sprinkle some slow-release fertilizer granules around the base of your lemon myrtle.
- Gently mix the granules into the soil.
- Water the soil thoroughly to activate the granules.
- You can also add a layer of organic matter as mulch. This provides extra nutrition, helps the tree conserve moisture, and provides insulation during the winter.
The Role of Fertilizers in Plant Health, Growth, and Development
Plants require four main types of nutrients; structural macronutrients, primary macronutrients, secondary macronutrients, and micronutrients.
The three structural macronutrients are carbon (C), hydrogen (H), and oxygen (O). These structural macronutrients are vital for the production of glucose. This important sugar is used to manufacture cellulose – the basic building block of all plant tissue.
Nitrogen (N), phosphorus (P), and potassium (K) are the three primary macronutrients. Nitrogen produces bushy foliage, while phosphorus is vital for flower production. Potassium helps plants circulate water and other nutrients more efficiently.
Secondary macronutrients perform various other functions and include calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), and sulfur (S).
Although plants get most of these nutrients through the soil, nutrients run out over time. That’s where fertilizers come in. Fertilizers replenish the nutrients in the soil, providing plants with optimum nutrition throughout the year.
Types of Fertilizers
Most fertilizers are either organic or synthetic. Organic fertilizers must be broken down by organisms within the soil before plants can absorb the nutrients. Synthetic fertilizers don’t need to break down, allowing plants to access the nutrients instantly.
However, synthetic fertilizers contain chemicals and salts that can kill beneficial organisms within the soil. Over time, this may reduce soil quality.
A fertilizer’s NPK ratio details how much nitrogen, phosphorus, and potassium each dose contains. Use fertilizers with more nitrogen if you want bushy foliage. If you want a beautiful display of flowers, choose fertilizers that contain more phosphorus.
Feed lemon myrtle trees once a year in the fall after the flowers stop blooming. Use slow-release fertilizers to give your lemon myrtle plenty of nutrition throughout winter and spring. Avoid harvesting the leaves for a few days after applying fertilizer.
For more, see our in-depth guide to growing and caring for lemon myrtles.