Not all plants need sunlight to grow while germinating. In fact, as little as one third of the seeds of all common garden and house plants need any light to germinate. Some plants actually do better with no light and thus their seeds are usually best placed deeper in the soil.
But what about Hibiscus seeds? Which group do they fall under?
Hibiscus seeds need sunlight to fully germinate, at least six to seven hours of exposure per day.
But that’s not all. For best results during germination, Hibiscus seeds need to be soaked for up to eight hours. And certain varieties may need to encounter several freeze/thaw cycles (known as stratification) before they will try to germinate.
While only the basics are necessary for Hibiscus seeds to germinate, if you provide them with these additional care practices, they will germinate and grow faster into a sprout, and will be ready to be transplanted in around ten weeks.
How Long Does it Take Hibiscus Seeds to Germinate?
Generally, Hibiscus seeds require two to three weeks to germinate. However, this is in ideal conditions. Otherwise, your plant may grow slower, potentially taking several months to germinate.
You want to make sure that the soil stays damp, exposed to plenty of sunlight, and that the temperature is around 75 to 85°F (24 to 29°C) constantly to provide the most effective growing conditions.
How Do You Grow Hibiscus From a Seed?
Growing Hibiscus from seed requires a little more care than growing from many other types of seeds. You can’t just simply place them in a pot with soil and expect good results. Instead, there are a couple of other steps you must take.
Do Hibiscus Seeds Need Light to Germinate?
Hibiscus are one of the plant species that need light to germinate. They enjoy having a lot of sun, usually at least six or seven hours sitting on a windowsill. If you are going to use plant lights instead of natural lights, aim for about sixteen hours of light via plant light per day.
Hibiscus need both a lot of light and warm growing conditions. This is true of both Hardy Hibiscus and Tropical Hibiscus.
How Do You Prepare Hibiscus Seeds for Planting?
To make sure your Hibiscus will be ready in time for planting outdoors, you want to make sure that you start planting seeds 10 to 14 weeks before the last estimated frost in spring. It is best to do this prep indoors, as you will want to keep the soil damp and warm.
If you plant outside, you will want to cover the ground to keep it warmer and to prevent the seed from dying.
Should I Soak Hibiscus Seeds Before Planting?
Hibiscus seeds have a hard outer pod that must be broken before the seed can start to germinate. There are two ways to do this. You can either nick the plant, or you can soak it.
Nicking is a delicate business and often more trouble than it is worth. You can either cut the seed pod open with a razor blade while being careful to not damage the insides or you can use sandpaper to open a small hole in the pod.
The easier method is to soak Hibiscus seeds. All you have to do is soak the seeds for about eight hours in room-temperature water. This allows the pods to soften up so that you can crack, or break off, the outer layer.
However, most people actually recommend doing both. After nicking the seed pod, soaking it for anywhere between one and eight hours helps to ensure that moisture manages to enter the seed.
While both of these methods aren’t technically necessary, they are important if you are trying to encourage your Hibiscus to germinate quickly. Generally, if these methods are used, Hibiscus seeds can germinate in just a couple of weeks, or a month if other conditions aren’t ideal.
However, if not done, then the seeds could take several months before they begin to germinate if they even do.
On the other hand, some people say that they do neither method and still manage to have their seeds sprout in just a few days, so it’s up to you how extensively you want to prepare.
How Deep Do I Plant Hibiscus?
Since Hibiscus need a lot of light you don’t want to plant them too deeply. Usually, a quarter inch (6 mm) deep into the soil is fine. As long as the seeds can manage to stay moist, you can even get away with just planting the seeds on top of the soil.
When planting outside, you generally want to situate Hibiscus about 2 to 3 feet (0.6 to 0.9 m) apart. This allows them to grow without competing for light, or space for their roots.
Note that Hibiscus roots are pretty shallow as well, so when it is time to plant them outside it is a good idea to make sure they aren’t in a place that is too exposed and windy.
Do Hibiscus Seeds Need Cold Stratification?
There are two main kinds of Hibiscus: Hardy and Tropical. For the most part, they look and function the same, but Hardy Hibiscus was designed to be able to survive colder winters.
The other significant difference is that Hardy Hibiscus will need to undergo several freeze/thaw cycles, also called stratification, before they will germinate. While you can just leave the seeds in a container outside and wait for a few freeze and thaw cycles to occur, you can also artificially create stratification.
The easiest way to do that is simply to place your seed pods in the freezer for a couple of days before taking them out and letting them thaw. Then repeat this a few times. This is a good option if you live in an area that doesn’t naturally undergo many freeze/thaw cycles.
Tropical Hibiscus don’t need to be stratified and are ready to undergo the germination process right away.
Besides the stratification process, both types of Hibiscus plants undergo and have the same requirements for germination, including nicking or soaking the seed pods.
Germinating Hibiscus Seeds in a Paper Towel
Germinating a Hibiscus seed can be done in a paper towel, too. This is a common way of germinating seeds to ensure that they will grow before planting them into the soil.
A lot of gardeners do the paper towel method first, as it stops you from wasting time with a pot and soil if the seeds aren’t healthy or strong enough to germinate.
For this method, all you need is water, your seeds, a container, and a paper towel. In lieu of paper towels, cotton or toilet paper are also effective.
Set the paper towel on a table, several layers thick. Then, place your seeds on top. You will want to space the seeds far enough apart that they have room to grow and sprout.
Make sure the materials are damp but not wet enough that water is dripping off. Most people will put another layer of damp paper towel over the seeds when using this method, but with Hibiscus that isn’t necessary as they like the light.
Once the plant starts to grow out of the seed and a green sprout appears, you can plant it outside or in a pot.
When to Plant Hibiscus Seeds Outside
While Hardy Hibiscus are designed to handle colder winters, when first planting your Hibiscus outside, it is a good idea to make sure the danger of frost has passed for the season.
To make sure you get the full benefit of summer growth, you will want to start germinating roughly 10 to 14 weeks before the last frost is supposed to occur. Once that last frost has thawed, you can start transplanting.
If you live in a warmer environment, Tropical Hibiscus can be planted in spring, summer, or fall.
Hibiscus seeds, whether Hardy or Tropical, do best with plenty of light (at least six to seven hours per day), warm temperatures around 75 to 85°F (24 to 29°C), and plenty of water. They are often planted just under, or even on top of the soil so that they can receive lots of light to allow for proper germination.
If you have struggled with Hibiscus in the past, you may need to consider putting the seeds through a few freeze/thaw cycles, nicking the seed pods, and soaking them before germinating. This encourages the seed to prepare for the process and often you’ll end up with seeds that are ready to grow and sprout faster.