Hibiscus Tree and Plant Care: Leaves Turning Yellow, Fertilizers, and Pruning

Hibiscus plants are famous and grown by many gardeners for their large, showy flowers. At the same time, some are familiar with it due to its flowers’ medicinal properties when served as tea. Hibiscus is one of my favorite flowering plants, along with these plants that bloom with purple flowers. They are originally native to tropical areas like Hawaii and Mauritius. You can also find them in Madagascar and Fiji.

In subtropical and temperate regions, you can find other species grown either in pots or out on the lawn. With over 200 species, it’s easy to get confused about which type is best for temperate zones. Which thrive in tropical zones? For you to easily determine which plant will grow best in your area, we’ll focus on tropical and hardy ones.

Tropical hibiscus thrives best in hot, humid areas and cannot withstand cold temperatures. It is best to grow tropical ones in Zones 10 and above or shelter them indoors or in a greenhouse if you live in Zone 9b. They produce bright blooms that vary in color. Some of their colors include:

  • red
  • orange
  • yellow
  • pink
  • purple
  • and white

Their foliage is glossy and has a deep green color throughout the year. It is perfect for their growth under the heat and sun in tropical areas. One of the most famous tropical varieties is Hibiscus rosa-Sinensis L., commonly known as Chinese hibiscus. It is grown as an ornamental plant in tropical and subtropical areas. This bushy evergreen perennial shrub is native to East Asia. It has various cultivars and hybrids that produce beautiful blooms as well.


Chinese hibiscus

On the other hand, hardy hibiscus can be grown in temperate zones. They are easier to take care of as they can tolerate cold climates. They’re better at withstanding the chilly air of winter in Zone 4, as long as they’re protected from the harsh frost. Some of the notable hardy hibiscus species include H. syriacus, also known as “Rose of Sharon” or “Korean Rose.” Another species is the H. moscheutos, also known as “Rose Mallow” or “Swamp Rose.”

H. syriacus is a deciduous perennial shrub that can grow up to 13 feet tall. It has short-lived flowers ranging from pink to white. They all fall within the day. The shrub continuously blooms during late summer or early fall. As a deciduous option, its leaves drop once a year but come back as a full bush during spring.


blooming hibiscus bush (Rose of Sharon)
Image source: Proven Winners

H. moscheutos is an herbaceous perennial plant that is native to North America. Its delicate showy flowers are named “dinner plate hibiscus.” They are 8-7 inches in size and bloom in different colors. Their colors include:

  • blue
  • pink
  • red
  • and white

It all depends on the variety. As an herbaceous plant, its stems die back to the ground each winter and grow back during spring.


red Rose Mallow hibiscus bush in full bloom
Image source: White Flower Farm

They can live for more than two years, regenerating yearly during spring from protected buds. It brings you colorful blooms for years every late spring without much fuss.

Growing & caring for it

It’s a given fact that you should plan your gardening efforts based on hardiness. Tropical hibiscus cannot handle cold and requires hot, humid areas. In contrast, hardy hibiscus can survive in cool climates. Thus, growing hardy hibiscus is less of a hassle if you’re in a temperate region. However, some people are fine with growing tropical varieties as an annual plant. The life cycle ends once the frost settles in.

Once you decide which type you want to grow, it’s time to familiarize yourself with the growth requirement. That way, you can fully enjoy their daily bloom from late spring to summer.

SOIL

The easiest way to start your gardening journey is to buy transplants from a nursery instead of growing them from seed. If you want to start growing from seed, you should sow your seeds indoors. Use a sterile potting mix a few weeks before the last frost. Follow the instructions in your seed packet. For more detailed instructions, read this article wherein we discuss how to grow them from seeds.

Before planting, it’s important to check the pH and type of your soil. They prefer slightly acidic soil, with a pH range of 5.5-7.5. If your soil is too alkaline, incorporate peat moss into your garden soil to increase its acidity. You can do this by adding 2-3 inches of peat moss on top of your soil and working it into the topsoil of your garden bed. For optimal growth, aim for a pH range of 6.0-6.5 since it thrives when put in soil with this pH range.

Put it in well-drained soils since stagnant water will promote root rot and cause it to wilt or get diseases. Keep in mind that some varieties like H. moscheutos prefer wet soils, which is why it garnered the name “Swamp Rose.”

The Miracle-Gro potting mix is a really good solution, and it even contains nutrients for six months.

miracle gro potting mix

TEMPERATURE AND HUMIDITY

They flower best when grown in humid areas with a temperature range of 60-90°F. When winter is approaching, you should transfer them indoors if they’re grown in containers and the temperature drops to 32°F. It’s at least the case for hardy hibiscus. If you’ve planted perennial hibiscus outdoors, it will die down into the ground during winter. You don’t have to worry since it will revive during spring.

For tropical hibiscus, move it indoors since a temperature lower than this can kill it when you notice the temperature nearing 55°F. Make sure to mist it when the temperature exceeds 70°F since too much heat may dry it out. Remember that tropical hibiscus thrives in humid areas.

This temperature rule extends to the water you use for your plants. It is important to never expose them to temperatures they cannot handle, especially for tropical hibiscus. Whether the room or water temperature, make sure it’s adequate. Take the extra step and get warm water from the faucet. Let the tap run until you get the right temperature. This way, your plant won’t suffer during watering.

Get a good hot water recirculating pump system in your home and an appropriate heater. It can provide the right environment for your hibiscus plants, even during winter.

How do I take care of hibiscus in the fall and in winter

As mentioned, you should bring tropical hibiscus inside once the temperature drops to 55°F. Not all varieties can handle the winter season outdoors. They still need to be transferred indoors when the temperatures reach below freezing. These varieties are better off put in containers or pots for easy transfer indoors.

To prepare for winter, prune up to a quarter of the new growth in fall. Remove all pests and insects, such as fruit flies. You can use neem oil or spray it with a strong water jet. It can’t be too strong, or you’ll damage it. For potted ones, move the pot indoors. You will need to dig it up and repot it into a container for ones grown directly in the soil. Use a soilless potting mix to avoid bringing soil-borne diseases into your home.

Once indoors, make sure to provide proper light and water to tropical hibiscus. Place it in a sunny window and use heating mats. If you don’t have a good amount of light shining through your window, make use of grow lights. You will need to tone down watering indoors during winter since the weather is cool. In contrast to tropical varieties, perennials will go into a dormant state during winter. They require a cool, damp location.

You will know which perennials can handle winter temperatures below freezing based on their hardiness. Those are the ones best planted directly in the ground. Just make sure to protect the roots with 3-4 inches of mulch. Come spring, it will revive with no problem at all.

There are simply some instructions to follow when it comes to Hibiscus.

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LIGHT

Hibiscus likes full to partial sun. When the sun gets too intense, there is a risk of damage during the summer. So if you live in a tropical region, aim for an area on your lawn that will not be too exposed to the blazing afternoon sun. If you live in a cooler temperate region, it is alright to plant it where the light during noon will reach them. Make sure that they are receiving around six hours of direct light daily.

When growing them indoors, you should situate the plants in a room with a southwest-facing window. There, they can get enough direct light daily. Suppose the sunlight cannot reach far into your room. It will be best to situate your potted plants on a multi-layered shelf. Give them enough space to be exposed to direct light without blocking each other. Suppose you’re worried about mold or fungi infestation on your shelves due to the chances of it getting wet while watering. Use a shelf made up of a material that won’t allow fungus growth that easily and can withstand humid conditions, which they prefer.

One example is this marine-grade plywood, which can survive repeated contact with water. It is made of high-quality wood that is cross-laminated and held together by waterproof glue. While we’re on the topic of making shelves, you might be interested in checking out portable bandsaw sawmills and wide belt sanders. They make woodworking much easier.

Suppose you’re doing well with providing yours with the amount of light they need. They will consistently produce flowers every day during their blooming season. Lack of bloom signifies it is not getting enough light. If the environment is unfavorable, they prioritize other growth or functions over flower production.

WATER

Tropical and hardy hibiscus differ in water requirements. Since tropical hibiscus is grown in warmer areas, you’ll need to water it more frequently. Their watering schedules range from once to twice a day, depending on the heat and humidity. This is why it must be planted in well-drained soil since frequent watering is needed. You don’t want stagnant water to accumulate, encouraging root rot.

In temperate regions, make sure to adjust your watering schedule based on the temperature. Water once or twice a day during summer. It needs less watering when the weather is cool since moisture is retained well in lower temperatures. Always check if the soil is dry to the touch before watering during fall and winter.

Maybe you’re a seasoned gardener or a dedicated hobbyist. You have a lot of plants to attend to that need frequent watering during the summer. You might want to check out these fuel transfer tanks that you can use to store water and fertilizer. These tanks will be especially useful if growing is your business and you have more than one garden or nursery to take care of.

Why do their leaves turn yellow (and how to avoid it)

When its leaves turn yellow, this is a sign that you’re overwatering. To avoid this, tone down watering during cool weather and only water when the soil is dry to the touch. But suppose you’ve already adjusted your watering appropriately, yet the leaves are still turning yellow. There might be an issue of stagnant water around it. If yours is located outdoors, try to have an irrigation system to drain excess water. If it is in a container, ensure that its drainage holes are not clogged.

FERTILIZER

Like flowering plants, they need fertilizers to support their blooming process. Unlike other varieties that do not require much fertilizing, supply these with well-balanced liquid or slow-release fertilizers. Remember never to overdo feeding, especially during winter when dormant. Overfertilizing may lead to toxicity and the burning of roots.

Best fertilizer

Hardy ones require a lot of potassium and a moderate amount of nitrogen. It only needs a low amount of phosphorus. You can opt for a fertilizer with an NPK ratio of 9-3-13 or 17-5-24 for your plants. Using diluted liquid fertilizer, only feed it once a week. You only need to apply slow-release fertilizers four times a year. It’s done during early spring, after the first bloom, during mid-summer, and during early winter. If your soil is fairly rich in nutrients to start with, lessen your feeding up to only twice a year. Only do it during early spring and at the end of summer.

The Miracle-Gro Shake ‘n Feed is our overall favorite fertilizer for all your gardening needs.

PRUNING

They do not require pruning, but they will encourage more bloom and a bushier plant since new branches will grow. However, you won’t want to use a lawn tractor for it. Here’s how to do it. 

When and how to prune

It is best to prune in the fall or early spring for tropical ones. Trim the growing stem tips to encourage more growth. If you prune too late in the season, do not cut too far back on the stems. Always prune dead or diseased branches. Only trim just enough branches to make the shrub less crowded to let in more light. You’ll see it thrive with more flowers and a fuller bush during summer.

Since perennial ones die down during winter, you can prune them down to the ground in fall. Do it preferably six inches above the ground. There’s no need to worry since it will revive in spring. You can also prune it just before the blooming season in early spring, when it has revived. Trim growing stem tips for more flowers.

Propagating

To propagate, you can use stem cuttings or seeds. The former is much easier and faster to grow. Check this article to learn how to grow seeds into plants.

shears

Propagating via stem cuttings

  • In spring, cut a section of a stem that has not fully matured yet. It can be a section with leaves but no flowers. Cut the section around 4-6 inches long. Make sure that there are no flower buds in the stem cutting. Trim any flowers if you see one.
  • Prepare a sterile potting mix in a container and moisten it. Make a shallow hole. Place the stem cutting in the groove and water the cutting. Gently pat down the potting mix around the stem. Cover the setup to create a greenhouse effect.
  • Place the pot in a warm area and out of direct sunlight, between 60-90°F. Keep the soil moist until the cutting takes root.
  • After eight weeks or so, you should see new leaves and your stem cutting properly rooted in the potting mix.

Growing them in a container

It is easier to grow them in a container if you don’t have enough space outside your home or grow a species that cannot survive winter. Here are a few reminders if you’re planning to grow them in pots:

  • Pick a container that has proper drainage holes and use a well-drained potting mix. It will be better if you use a soilless potting mix to avoid exposure to soil-borne diseases.
  • It is better to use stone pots instead of clay pots. The latter can make the soil alkaline over time. Since they prefer slightly acidic soil, you should avoid clay pots.
  • Newly planted transplants or stem cuttings must be kept away from direct light for the first two weeks. This allows them to adjust and take root growth seriously. Once the plat is well-established, place the container in an area where it can have six hours of direct light.
  • Feed them liquid fertilizers weekly, or use slow-release fertilizer that can last up to six weeks.
  • Water them only when the root is dry to touch in winter and fall. Water more frequently in summer, once to twice a day.

If you’re looking for more plants to grow that are easier to take care of compared to hibiscus, I have a few suggestions for you:

  • You can check out Sansevieria or snake plants, which are options that can thrive indoors. They can survive even in low to medium light and need only minimal watering. Once a week or every two weeks is all they need. Some cultivars can easily fit on your desk, growing only up to 6 inches tall. There are also varieties that can grow up to 4 feet tall. They can remove toxic pollutants in your home and are featured in a clean air study conducted by NASA. We also have a guide on cucumber leaves.
  • If you want another outdoor type that can give you shade and bloom, check out these dwarf shrubs. You can pair both non-flowering and flowering perennial dwarf shrubs with the hibiscus on your lawn. It will give you a wonderful and balanced bloom during spring through summer.

Making a microclimate

Plan to grow and propagate many tropical plants, whether for business or as a hobby. If the climate in your area is not suitable for it, explore microclimates and use greenhouses to shelter them.

A microclimate is an environment within a restricted area that differs from the surrounding area, wherein your plant can thrive. Using a microclimate can be done in numerous ways. You can use grow lights as a source of heat and light indoors. Otherwise, use greenhouse covers or humidifiers to increase moisture and humidity. It will be best to build a nursery in a greenhouse so you can shelter more of them.

If you plan to do this, use materials that will not easily rot or get infested with molds. They need to withstand hot temperatures and humidity, such as this marine-grade plywood. Wood is not the only thing you will require to build a proper greenhouse.

You might want to check out this plasma cutter that can easily cut through stainless steel. Since you’re still setting up a new greenhouse, power sources may not be readily available at the start. Check out this portable engine-driven welder that you can take anywhere so you can weld anytime. You don’t even need an external power source.

FAQ

What kills a hibiscus tree?

A Hibiscus plant is native to warm temperatures and is typically found in tropical regions. Therefore a sudden drop in temperature or frost is likely to kill the plant. Additionally, low humidity or direct airflow and dried-up soil significantly destroy the plant’s health.

Are hibiscus trees hard to take care of?

Hibiscus trees are hyper-specific about the climate. They can’t survive in sub-zero temperatures and require certain warmth to grow. They also need to be watered with warm water and require tons of direct sunlight to bloom. Apart from the climatic conditions, the plant isn’t too specific about the container size or spacing. With the climatic conditions met, it tends to be a low-maintenance plant otherwise.

Why are my hibiscus leaves turning yellow and falling off?

There are multiple reasons why the leaves of your Hibiscus are turning yellow. However, at the top of the list is nutrient deficiency. If your plant isn’t getting the required blend of nutrients, it’s likely to develop iron chlorosis which causes the leaves to turn yellow. Other than that, changes in the temperature or the environmental conditions also affect the pigmentation of the leaves. Lastly, the damage caused by an insect infestation could result in a yellowing plant.  

How much sun does a hibiscus need?

A Hibiscus requires ample amounts of direct sunlight so it can fully bloom. The plant’s growth isn’t affected by low sunlight, but the flowering process is highly dependent on it.

How big do hibiscus trees get?

Make sure a Hibiscus tree is well taken care of with the right blend of required nutrients and a thorough watering schedule. It can grow up to 8 feet tall and 6 feet wide.  

How fast does a hibiscus tree grow?

The Hibiscus plant reaches maturity within 2 to 3 years. The growth rate is considered considerably high given the height it reaches. 

Where is the best place to plant a hibiscus tree?

The growth of a hibiscus tree is highly dependent on direct sunlight. Therefore, an area that gets sunlight for 5 to 6 hours a day is ideal.