Hibiscus-specific Fertilizers

Long before I started hosting GardenLine in 1996, I had the question most typical homeowners have: Why isn’t there one fertilizer for everything?

Shouldn’t there be an all-purpose, one-size-fits-all fertilizer I can just throw out maybe a couple of times a year? That would make everything hunky-dory!

Courtesy Michael Manion

Courtesy Michael Manion

But let’s be realistic. If a fertilizer works for the lawn, it’s probably not going to be good for, say, roses. Right? What’s good for roses isn’t good for plumerias. What’s good for plumerias isn’t good for vegetables or herbs. Or hibiscus. Or azaleas.

Sure, there are some great all-purpose fertilizers that can be applied to lawns, trees, shrubs and herbs. But that same blend would have the wrong effect on tropical blooming plants like alamanda, hibiscus and bougainvillea.

So that brings me to the need for fertilizers especially for hibiscus and other blooming tropicals. I decided to write this profile after I saw an exchange on a Texas gardeners Facebook group. A lady asked why her hibiscus buds were dropping, and some of the responses chilled my horticultural spine. Bloom boosters were being recommended in response after response. Bloom boosters are fertilizers with high levels of phosphorous - the middle number in their ratios, like 10-50-10 and 15-30-15.

Randy's braided hibiscus

Randy's braided hibiscus

Sure, one might think that hibiscus fertilizers would have such high-phosphorus ratios to promote blooms. But, that’s entirely too much phosphorus. It’s the first number - the nitrogen - that’s most important. And with plants that need higher nitrogen levels, too much phosphorus usually locks up the other elements and prevents the plant from processing them.

The second most important element in a fertilizer for hibiscus is potassium - the third number in the ratio. Hibiscus have a voracious appetite for potassium, which assists in photosynthesis - the process that uses sunlight and water to create sugars for food. The sugars are needed to build every part of the plant, and hibiscus, with their huge, complex and colorful flowers, need more potassium than most plants. Potassium also draws water into plant cells, keeping them plump, hydrated, and healthy. And that makes the plant lusher, prettier and more resistant to drought and disease.

In fact, any plant that blooms on “new” wood will benefit from hibiscus food. So, if you truly want the best from yours, look for these local foods that have it nailed:

  • Nitro-Phos 12-3-16 (in 4-pound jars)
  • Nelson’s NutriStar 10-4-12
  • Space City Chapter (of the Hibiscus Society) 18-10-28 (I use this exclusively on my braided hibiscus, pictured)
  • Ferti-lome Hibiscus Food - 17-7-10

There are also some all-purpose organic products on the market that can make good stop-gap fertilizers for hibiscus. An example is MicroLife 6-2-4, which has a higher ratio of nitrogen and potassium. But when it comes to optimum hibiscus performance, they’ll be infinitely better off with the synthetic and blended fertilizers listed above.

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