If any of you are like me, you rely on the advice of the employees at your local nursery as to what kind of fertiliser you should use on your plants.
Various nutrients are essential for plant growth and flowering, and although many plants draw enough nutrients from the soil to survive, supplementing them with added nutrients in the form of fertiliser can mean the difference between a plant merely surviving and it flourishing.
However, fertilising is such an integral part of creating a beautiful garden, that I decided to find out a bit more about the various different kinds of fertilisers out there and when the best time to use them is.
What makes fertilisers so important?
Various nutrients are essential for plant growth and flowering, and although many plants draw enough nutrients from the soil to survive, supplementing them with added nutrients in the form of fertiliser can mean the difference between a plant merely surviving and it flourishing.
Over time, rain and irrigation flushes the nutrients away, and as such, periodic fertilising is an essential way of keeping your plants happy and healthy, and your garden looking in tip-top shape.
What is in the different fertilisers?
There are three main nutrients, called macro-nutrients that plants require, including:
There are three main nutrients, called macro-nutrients that plants require.
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Nitrogen: This nutrient’s main responsibility is to ensure that the plant is green. It is found in abundance in rainwater, especially rain that has fallen during a storm with much thunder and lightning, as well as in fertilisers and compost.
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Phosphorus: Also known as phosphates, this is a nutrient that is often missing in our soil. Its main function is to aid root and stem development. It is not efficient to apply this to the soil surface, as it does not leach into the soil well. As such, it is best to incorporate phosphates into the soil when planting.
- Potassium: Another name for potassium is potash, and it aids plants with the production of flowers.
Plants also require what are termed micro-nutrients, but in much smaller quantities, which include nutrients such as iron, manganese, copper and aluminium for example.
Today, fertilisers are available in various combinations for nutrients, for various different applications. They can be divided up into two distinct groups – those with macro-nutrients, which include nitrogen, phosphate and potassium; and those that contain both macro- and micro-nutrients.
Plants also require what are termed micro-nutrients, but in much smaller quantities, which include nutrients such as iron, manganese, copper and aluminium for example.
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Macro-nutrient fertiliser: This kind of fertiliser always contains a mixture of nitrogen, phosphorous and potassium, but the ratio of each varies from product to product. For example, 2:3:2 fertilisers contain 2 parts nitrogen, 3 parts phosphorous and 2 parts potassium. On the other hand, 3:2:1 fertiliser contains 3 parts nitrogen, 2 parts phosphorous and 1 part potassium. Macro-nutrient fertiliser should be used approximately two to three times a year.
- Fertilisers that contain macro- and micro-nutrients: These fertilisers contain everything required by plants – making them a virtual super-food for optimal growth. They are mostly tailor-made to best suit various groups of plants, such as roses, acid-loving plants, ferns, vegetable plants, and so on. There are multi-purpose fertilisers of this ilk, however, that serve plants in general, such as Multifeed and Phostrogen for example.
When is the best time to fertilise your garden?
You should only add fertiliser to your garden from the beginning of spring, through to mid-summer, when most plants are at the peak of their growth and flowering periods.
Adding fertiliser from late-summer, through autumn and winter is a complete waste, as any new growth on plants will be destroyed through the colder months and most plants become dormant throughout winter, so they don’t require added nutrients at all.
What do various plant groups require?
Flowering and fruiting plants: Fertilisers with a high ratio of nitrogen for greening, a low ratio of phosphate and a large ratio of potassium for improving flowering potential, are best for flowering and fruiting plants. For example, macro-nutrient fertiliser such as 6:1:5 is ideal for fruit plants and shrubs, and 8:1:5 is ideal for roses.
New planting: When planting new plants, including trees, shrubs, seedlings and lawn, it is advisable to add Super Phosphate and general fertiliser, such as 2:3:2 to the mix. When planting new vegetables, you can use Super Phosphate and a veggie-specific fertiliser, such as 2:3:4 to the mix. The Super Phosphate is essential for the formation of strong roots and stems, while the fertiliser helps with the greening, stem and root growth and the flowering of the plant as it develops.
Lawn: Since lawn comprises foliage and roots, the ideal fertiliser for lawn should have a high content of nitrogen for greening the foliage, as well as a lot of phosphorous for developing a strong root system. Since it doesn’t have any flowers, it requires a very low potassium content. Ideal lawn fertiliser comprises 7:1:3 or 3:2:1 for example. – Antonella Desi
