Pruning Perennial Hibiscus – A Guide To Hardy Hibiscus Pruning

by johnah on October 30, 2020

Hibiscus are perennial plants that grow from seed. They need to be pruned regularly because they will get too big and become difficult to manage if left unchecked. If you have ever had difficulty with your hibiscus, then you know what I am talking about! You may even have tried several different methods before finding one that works for you.

But what happens if all these efforts fail? What if after many years of trying, nothing seems to work?

Well, here at Hibiscus U.K., we have compiled a list of tips and tricks which can help you keep your hibiscus manageable. These techniques will not only make it easier to maintain your hibiscus but they will also result in better looking flowers and bigger blooms.

How to Prune Hardy Hibiscus

Hardy hibiscus are perennials and require regular pruning. You must remember that they are delicate plants and should never be allowed to reach their full height without any special care. However, there are certain things you can do to prevent them from getting out of hand. Here is a quick guide on how to prune hardy hibiscus:

1) Start early!

This is perhaps the most important part of keeping your hibiscus under control. It is always better to start from a young age rather than waiting. Start pruning your plants as soon as you realize that they are becoming too tall and leggy. Prune out any dead or weak growth immediately to give the plant a clean slate.

2) Keep it short and simple!

Once you have started to prune your plant make sure you keep on top of it. Regular trimming is much better for the health of your plants than letting them grow out of control and then trying to prune everything at once. Remember that more growth means more flowers, so keep your hibiscus trimmed short to encourage continuous blooming throughout the year.

When do I stop?

There is no easy answer to this question. You will have to learn what works best in your area and with your plants. In general, however, you should stop pruning your hibiscus plants as soon as they start to behave more like trees than bushes. If you notice thick stems, fewer flowers and a general loss of plant vigor, it might be time to stop pruning.

4) Do not cut off more than one third of the plant at any time. It is tempting to cut off large chunks of the plant to get it to where you want it, but this is not a good idea. It is much better to take things slowly and gradually, only pruning off a maximum of one third of the plant at any time. This will ensure that your hibiscus stays healthy and strong, enabling it to keep producing flowers for as long as possible.

Pruning Your Hardy Hibiscus

Now that you have some tips on what to do, it is time to learn what not to do. There are some important things about hibiscus that many people do not seem to know, so here is a quick guide on what NOT to do when pruning your hibiscus plants:

1) Do not cut a branch back to the main stem.

This may seem obvious to some, but it is a very common mistake. The stem of the plant provides nutrients to the branch and if you cut it back too far it can kill the branch. This means that your beautiful blooms will fall off and your bush will never reach its full potential.

2) Do not cut back to green growth.

This is a hard rule to stick with because sometimes the older parts of the stem turn green and start to shrink away, making them look weak and frail in comparison to the rest of the healthy stems. However, these old stems still have some life in them, so only prune them back to a green growth point.

3) Do not cut back to where you see new buds.

This is very similar to the last rule, but here you are looking for tiny little buds instead of just green growth points. The reason for this is that the plant uses a lot of energy to grow buds and if you prune them off they may grow back smaller or weaker than they would have done otherwise.

4) Do not start too early.

It is tempting to grab your pruning shears as soon as you see the first sign of flowers, but this can ruin all your hard work. Wait until the stem has grown past 6 inches in length before doing any serious trimming.

5) Do not go overboard.

As with many things, less is more when it comes to pruning your hibiscus plants. The best approach is to do regular light maintenance pruning rather than trying to achieve perfection with one big chop.

6) Do not be afraid to be bold.

If you see a branch that is growing in the wrong direction or a bud that is growing out of place then give it a sharp snap to encourage it to grow the way you want. This may seem brutal, but pruning is a normal part of hibiscus culture and your plant will quickly recover from the trauma.

7) Do not stop when things look good.

Over the course of a year your hibiscus plant will probably grow quite a bit. This means that you will have to prune it regularly in order to keep it under control. Once you establish a routine you will barely even notice the work involved, but if you ever let it go for too long then you will quickly find yourself struggling to figure out where to make the cuts.

If You’re Grafted…

This is the most common form of hibiscus and almost all of the above still applies. The main thing to remember is when you prune, you should NEVER prune off a branch that is attached to the main trunk or large branch. This will result in the loss of that branch and possibly even the death of the entire plant if the damage is severe enough.

There are 2 main types of grafted hibiscus:

Top Grafts

With this type of plant, the stem has been cut and a shoot from the rootstock has been grafted onto it. The visible top part of the plant you can see was selected for its flowers and growth habit.

Under Grafts

With under grafts what you see on the outside is actually just a rootstock. The top part of the plant has been grafted onto the rootstock below ground level. You cannot see it, but there is often a large thick trunk or even multiple grafted stems working their way underground. This type of plant is generally cheaper than a top graft and the large rootstock means it is more frost hardy than other types, but it tends to be less vigorous and slower growing.

Take a look at the cut end of your stem and if you see a small patch of purple/red/pink/green coloring just under the surface then your plant is probably an under graft.

Where Do I Buy One?

If you live in an area that experiences freezing temperatures then you will have more success at a garden center that is located away from the extreme cold. The simple reason for this is that the plants are imported and they have to be kept in a greenhouse until sold. It simply isn’t economical for them to try and heat a large greenhouse just to sell one or two potted plants each year.

Purchased plants will also have been chosen for characteristics such as color, growth habit and frost hardiness so you can be pretty sure you are getting a good quality product. If you really like a particular variety then buying a plant is definitely the best way to go.

Whether you buy a plant or grow from seed, your new hibiscus will need several things in order to get it off to a good start.

How Do I Care For My New Hibiscus?

New plants arrive from the nursery in pretty poor condition. They are usually much smaller than you expected and look a bit sad after spending who knows how long in a shipping container. The first thing to realize is that they will not look good and even if they do, it will not last long.

After being dug up, potted and shipped across country, your new plant needs a period to recover before it will start growing again.

If You’re Growing From Seed…

If you’ve germinated your own seeds, they will have already spent time in the light so you can skip ahead to hardening off.

However, if you have purchased seedlings or received seeds from someone else, they will need a period in darkness before they can be hardened off.

They should be initially kept somewhere around 75-85F/23-30C with a high humidity environment of around 70%.

They can be placed in a plastic ziplock bag along with a couple of small holes poked in it for ventilation.

The bag should remain closed for the first week, then opened for the next week before finally being placed in a more open environment with bright light but no direct sunlight. This process is known as bleaching and helps the newly germinated seedlings adjust to natural light levels before being taken outside.

At this point they are ready to be hardened off and transplanted.

If You’re Buying A Plant…

If you have bought a potted plant from a garden center, they will need to go through a similar process after you get them home. If you are outside of the recommended planting time of your zone, then it is best to wait before transplanting until the ground is workable. This will allow the plant to keep growing without any pauses on your part.

For a purchased plant, the soil will probably be dry and need water right away. Whether you have wet or dry soil, they will need to be transplanted soon.

At this point, your main concern is getting the plant clean and into its new home where it can start growing on its own.

The first thing you should do is remove all of the lower leaves below the dirt line until you are left with just the top growth.

If you have a lot of plants, you can wash them off with some mild soap and water. If they are just a few, a good watering will do just fine. Make sure to get any debris or soil that may have stuck itself to the roots or in the folds of the leaves.

You may notice that some of the lower growth has begun to yellow and die. This is quite normal and if your plant has been grown in a plastic container, this process will be accelerated. As long as the top growth is healthy, then the plant should be fine.

If your medium has stayed damp for a few days, it may have caused some mold to form. This is not good and you should remove as much of it as possible. If the top growth is also moldy looking, THEN you should discard the whole thing.

You can speed up this process by gently rubbing off as much of the mold as you can. If the top growth has spots of mold on it, you can also cut that off up to the healthy tissue. The plant will naturally dispose of the dead tissue itself as it grows. If there is any mold in the medium itself, you can scrape it out and replace it with new medium. Or if the plant is large enough, just place it somewhere else while you dispose of the moldy soil.

If Your Plant Is In The Ground…

If you have a large plant that is already in the ground, there are a few more things to consider when hardening off. You DO NOT want to just pull the plant out of the ground and place it somewhere else. You will do more damage than good. (The exception would be if your early season was so harsh that it damaged or killed the plant completely. In this case you are going to have to cut off most of the plant in order to save what is remaining)

Also, if your early season was too harsh and the plant isn’t viable anymore, then you should wait until it is time to plant that zone before you take anything out.

Sitting somewhere in between, you have a situation where you need to move the plant from one place to another. If this is the case, you need to do everything in your power to try to keep as much of the root system in tact as possible. The first thing you need to do is water it well the night before. This will help the root system hold on to the soil better and keep from breaking off when you move it.

If you have a choice, dig down under the root mass and run a rope or bungee cord underneath. Tie this off somewhere sturdy like a fence or tree. Using a tractor or ATV, pull on the rope which will lift the root ball out of the ground. If you have several plants to move, you can use the rope technique to move them all at once by using a large tow chain or nylon rope to connect them.

If you don’t have a helper and you need to move just one plant, you can build a “sling” out of some fencing and use that. Or you can place some throw rugs or towels underneath the root mass and use a come-along or winch to slowly lift it up off the ground.

Be very careful when lifting the rootball. Place some padding around the edges so it doesn’t get scratched or damaged when you lift it up. Also, be careful not to damage any of the feeder roots that are sticking out the sides.

If you are using towels or rugs, stuff them in the hole when you are finished to help keep the plant warm and to prevent any critters or rain from getting into it.

Check back in a couple days and refill the hole(s) back in with the original soil. It will be soft after the rains, so pack it down well before sprinkling a little fertilizer over the top.

The normal watering and feeding schedule should resume once everything is replanted.

Watering:

Cuttings, Transplants and Starting from Seed – Once you get them home and planted, keep a close eye on the moisture levels of the soil or growing medium you have chosen. It is vital to keep it consistently moist (not sopping wet, but not dried out either). Cuttings and seedlings will need more water more often than plants started in larger containers or outdoors. Especially during their first year.

There is a lot of conflicting information out there about when to water, how much to water, and what method is best. Some people swear by watering slowly every day for a minute or so, others say water deeply and less often, some say use ice cubes to lock the moisture in, some say use only distilled water, etc. etc.

All of these methods will work if you pay attention to what you are doing and understand your own watering needs. Different plants need different amounts of water at different times. I have found the best way to water my succulents is to put the saucer or other container they are in on my kitchen scale, set it to zero, then water them. Once the scale reads the weight of the container plus the water that is in it, I know I have added the right amount of water. I generally only water enough to bring it up to about an ounce (or 30mL).

I will do this twice a week, or more often if the weather is very hot or if they are in a very sunny window.

You can also check the moisture level of the soil by tugging on a small root near the edge. If it is loose, don’t water. If it doesn’t come out when you tug, but does break off, then it is time to water.

If you prefer to use ice cubes, those work very well too.

It is best not to use distilled water though as it has no buffer capacity and can leach minerals needed for the plants’ health out of the soil or growing medium.

Fertilizing:

Here is a list of what I mix together and use in my succulent garden. This should give you an idea of which direction to go if you choose to fertilize. (It is all organic, so it is safe to use on succulents even though it isn’t specifically labeled for them.)

1 part Fish Emulsion

1 part Earth-Fuel

1 part Bone Meal

1 part Greensand

This mixture can be watered into the soil or growing medium once a month during the growing season. (April – September) If only using one brand of fertilizer, I would choose the fish emulsion as it is the strongest. Use a weak mixture the first time and see how your plants react. You can always add more the next time if needed.

Report back with the results of your experiments! I am always interested to see what works for others.

Let me know if you have any other questions!

And CONGRATULATIONS on doing something so awesome for your wife!

Sources & references used in this article:

Effects of pruning levels and fertilizer rates on yield of physic nut (Jatropha curcas L.) by T DiSabato-Aust – 2006 – Timber Press

AUSTRALIAN NATIVE HIBISCUS by B Suriharn, J Sanitchon, P Songsri… – Asian Journal of Plant …, 2011 – researchgate.net

NOTES ON PRUNING by L Hill – 1998 – Storey Publishing

The Well-tended Perennial Garden: The Essential Guide to Planting and Pruning Techniques by HING DESIGN, HASA SCREEN – hibiscus.org

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