Hibiscus Fertilizer
Choosing The Right Hibiscus Fertilizer
Choosing the correct hibiscus fertilizer can be a bit tricky. It's not that the hibiscus, be it a tropical hibiscus or hardy hibiscus, won't tolerate an all purpose fertilizer, but if you want the plant and its lovely blossoms to be at its best, a fertilizer with just the right mix of ingredients is a better choice. Those hibiscus lovers who enter their plants in competitive shows are often very picky when it comes to choosing what they consider to be the right hibiscus fertilizer.
The hibiscus is a member of the mallow family, and there are just over 200 different species of the plant. The species vary from small single annual plants to perennial plants, shrubs, and small trees. Hibiscus shrubs often form the basis for hedges, which can be quite stunning. The tropical varieties generally have blooms in the neighborhood of 3" to 6" in diameter, although a few hybrids have blooms nearly double that size. The hardy hibiscus often has slightly larger blooms with a number of varieties having blooms that fall into the dinner plate category. Hardy hibiscus will generally overwinter in Zone 5 and above. The hardy hibiscus is not suitable for a shrub or hedge as it dies back to the ground each fall.
Hibiscus are heavy feeders and need to be transplanted as soon as is practical if they are purchased in a pot containing peat most or ordinary potting soil, neither of which contains nutrients sufficient for the plant's needs. To get the right kind of hibiscus fertilizer, is pays to know what the numbers on a box of bag of fertilizer stand for.
The NPK Numbers - The three numbers on the container of fertilizer are called the NPK numbers. The letters stand for the chemical elements nitrogen (N), phosphorus (P), and potassium (K). The value indicates how many pounds of a given element there are in each 100 pounds of fertilizer. The ratios between the numbers are key, as the amount of one element with respect to the others is of significance, a while the value of the three elements indicates the strength of the fertilizer. A 10-10-10 fertilizer is twice as strong as a 5-5-5 fertilizer. 100 pounds of a 7-2-7 fertilizer would contain 7 pounds of nitrogen, 2 pounds of phosphorus, and 7 pounds of potassium.
Potassium Requirements - Of the three elements, potassium is generally considered to be the most important when growing hibiscus. Potassium plays a key role in photosynthesis, helps keep the plant hydrated, and also plays a key role in building the large beautiful flowers the hibiscus is noted for. As much as the hibiscus plant needs potassium, it is not particularly efficient when it comes to storing it, and the supply needs to be constantly replenished to keep the plant at its best.
Phosphorous Requirements - Phosphorus is a key nutritional element for many plants, especially when it comes to root development. This is definitely not the case with the hibiscus however, which can be damaged over time if an excess of phosphorus is being provided. High phosphorus fertilizers are sometimes applied to hibiscus plants with the objective of obtaining larger booms. While this has certain validity, it is usually a one time benefit, if the blossoms benefit at all. Too much phosphorous ties up other minerals the plant must have, with the result the plant slowly, and in some instances rapidly, starves to death.
Nitrogen Requirements - The hibiscus needs nitrogen, as do all plants, especially if the plant is to have attractive and healthy foliage. The hibiscus only requires nitrogen in medium amounts. Too much will not be as damaging to the plant as would too much phosphorus, but an excess of nitrogen can in some instances make the edges of the leaves of the plant "burn" and turn brown.
Optimum NPK Numbers - The NPK number 7-2-7 quoted above, is a good ratio for a hibiscus fertilizer. It contains a small percentage of phosphorus and the amount of nitrogen is not too high at 7 pounds per 100 pounds of fertilizer. A general purpose 10-10-10 fertilizer may work in some instances, though the amount of phosphorus is a bit high. An optimum NPK number would be in the order of 15-5-25. In this case the hibiscus would get an ample feeding of potassium, very little phosphorus, and a medium amount of nitrogen. Higher values of nitrogen could cause leaf burn. If that were the case, the best remedy is to let the plant go without fertilizer for a period of time, and then feed it with a hibiscus fertilizer containing a smaller proportion of nitrogen.