Hibiscus are extremely floriferous plants that produce multiple blooms throughout the season.
Whilst it’s no secret that you need to be pinching off spent flowers to encourage new growth, you do need to know when the flowers are ready to be removed.
How Long Do Hibiscus Blooms Last?
The blooms on hardy and tropical hibiscus plants only last one to two days at most. Specialty hybrids can have longer-lasting blooms, some lasting up to one week. During the bloom cycle, when one flower drops, a new bud opens. On most varieties, the buds emerge on the branch tips, open in the morning and start to wilt late afternoon, then drop in the evening or the next day. The bloom cycle repeats from early Spring to late Fall outdoors. Tropical hibiscus can be kept in bloom all year indoors.
The Low Down on Getting More Blooms from Hibiscus Plants
For hibiscus to bloom, it needs water, sunlight, fertilizer, and a consistent temperature range. Ideal temperatures are 50 to 70 degrees Fahrenheit (10-21 degrees Celsisus).
Watering and light are the two things you should monitor throughout the season as those will change.
Watering Frequency to Encourage Flowering
Watering hibiscus is a tricky balance because the end goal is to prevent the soil from drying out. Once that happens, the blooming processes start to shut down.
You may only see a slight wilting when the soil dries out, but that is the result of the plant shutting down to preserve energy. The only way to counter that is to keep the soil moist by watering more when the temperatures soar.
For hibiscus planted in garden soil, that also means you need to water more deeply.
Perhaps even apply a layer of mulch to prevent the water from evaporating faster than the plant can drink it.
How Container Sizes Impact Flowering
If you’re growing hibiscus in planters, the size of the pot will affect its flowering cycle. In containers, letting a hibiscus become semi-pot bound is good.
Without the space to support root development, most of the plant’s energy is channeled into flowering. The result is you get more blooms from a semi-pot-bound plant.
Fertilizer Requirements and Application Rates
Hibiscus do need feeding with fertilizer but don’t be tempted to use a super blooming plant food.
Bloom boosters are toxic to hibiscus! They tie up other key nutrients like iron.
The key to fertilizing hibiscus is applying it light and often.
Use a low phosphorous fertilizer and even then, still dilute it to half strength and apply it weekly from April through to September.
The phosphorous number is the middle digit on labels. It’s the P in the NPK. Good fertilizers for hibiscus are always lower in phosphorous, such as 12-4-8, or a 7-1-2 fertilizer.
Sunlight Intensity and the Effects of Shade
Sunlight promotes flowering and hibiscus do best with six hours daily. They will bloom with as little as two hours of sunlight, just not as much.
If they receive less than two hours of sunlight, you’d just be growing a green bush without any flowers.
This can happen when you try to grow hibiscus as a houseplant in small pots located near a window. If it doesn’t get at least two hours of sunlight daily, it will not bloom.
Shade affects blooming too because it can block the usable light the plant receives.
While it is true that hibiscus is tolerant to shade, the type of shade matters a lot.
Solid shade caused by sunlight being blocked by a house, fence, shed, or garage reduces PAR (photosynthetically active radiation), which is the usable light plants need for photosynthesis.
Dappled sunlight, such as the shade from the canopy of trees and taller plants around a hibiscus will have more usable light.
The better the light intensity, the faster the photosynthetic rate, and that’s what hibiscus need for flower production.
Frequently Asked Questions about Hibiscus Blooming
Will re-potting a hibiscus encourage blooming?
Potted hibiscus needs to be re-potted every two to three years. They bloom best when they’re semi-pot bound, but if they become entirely root bound, the decrease in oxygen in the soil will cause blooming to suffer.
Why are the buds dropping before they open?
Bud drop is common on double petal varieties of hibiscus. It happens when the plant is under any type of stress. The most common stressor is insufficient watering, usually when temperatures rise at the peak of summer. If water isn’t increased in line with the temperature rise, the plant gets stressed and drops buds instead of blooming. A stressed hibiscus will always bloom less. That’s why it’s imperative to water more in the summer months than you do in early spring when temperatures are cooler.
Marcel runs the place around here. He has a deep passion for houseplants & gardening and is constantly on the lookout for yet another special plant to add to his arsenal of houseplants, succulents & cacti.
Marcel is also the founder of Iseli International Commerce, a sole proprietorship company that publishes a variety of websites and online magazines.