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Hibiscus Plant Care

Pruning Hibiscus


Saffron a few months after a full pruning
If you grow any kind of plant, shrub, or tree, sooner or later you will have to decide whether or not to prune. But what is pruning really? Do all plants need it? Are there any benefits of pruning? This article should tell you everything you need to know about pruning.

 

What is Pruning?

Pruning is defined as "trimming or cutting branches to improve growth and appearance." There are many different pruning techniques, depending on what you want to achieve. Some people equate pruning with chopping a plant down to the ground. For others it's nipping off the green tip of a branch. Any time you physically interfere with the natural growth of your plant, you're pruning. To make it easier, let us break down pruning into the following categories:

 

Why Prune?

So why prune? We all grow hibiscus primarily for the flowers. We tend to forget how important the bush is. Pruning stimulates branching and makes a fuller bush. Why is that so great? Hibiscus form buds at the end of each branch. The more branches, the more flowers. It's that simple. If that's not a compelling argument to prune, we don't know what is!

We all hate to prune our plants while they are blooming because we don't want to lose any flowers! But the long-term payoff is that pruning stimulates more side branches on your plants, and every one of these new branches will produce even more blooms eventually. That is the basic equation for pruning - some blooms now if you don't prune or more blooms later if you do. You also get the added benefit of having a better looking bush if you prune.

There are compromises luckily! You don't have to prune all the branches at once. You can selectively prune a few branches at a time, and keep some flowering branches on your plant through the blooming season. Or you can just selectively prune stray, unattractive, or sick branches. Any pruning helps the plant and produces more blooms in the long run.

 

When to Prune

When to prune depends on the specifics of your area and growing conditions. The main idea is to prune just before a warming trend is coming, so that your hibiscus will grow very actively, and the increasing warmth will pull them forward into lush new growth. Pruning just before very cold weather can be so stressful that it can cause severe dieback, and you can lose more of your plant than you want to. But pruning in extreme heat can be equally stressful. The very best time to prune is times of sunny, mild weather. For some of you, this will mean you can prune any time all summer long. For some of us, it means spring or fall are our optimum times for pruning. Here are some basic guidelines:


A tall skinny hibiscus can be pruned
to create a rounder, fuller bush.

 

First, Take a Good Look at Your Plant

Okay, you're now ready to put the pruners to the plant, but wait a minute. There is one more thing to take into consideration. As you look at the branches, you will see that the leaf nodes (eyes) point in different directions, some in toward the center of the plant, others sideways, outward, and some even downward. You may also have some branches with an almost horizontal or downward pointing growth habit. Perhaps there is a "hole" in the leaf canopy. Where you place your cut will either correct the problem or make it worse.

The general rule of thumb is to make the cut 1/4" (1/2 cm) above an outward pointing node. This works well with staunchly upright plants, as they do need to spread a little. You do want a little spreading of the branches to encourage lateral growth and increase flowering. This is how the majority of us have learned to prune and in most instances it works very well.

However, if a plant has a spreading growth habit, you don't want it to fall apart but make it more upright. "Spreading" means plants where the majority of the branches point outward at an angle that exceeds 45°. For these plants we recommend cutting 1/4" (1/2 cm) above an inward-pointing node instead. This will force new growth to become more upright.

 

Tools


Pruning forces branching,
which means more buds & flowers
For pruning only one tool is generally needed - a pair of good pruning shears, often referred to as pruners. Your pruners need to be sharp and clean. Dull or dirty pruners can spread disease all through your garden. So along with your pruners, get a bottle of alcohol gel hand cleaner, and use it on your pruners every time you move to a new bush, or after every cut of diseased wood.

 

Let's Start Pruning!
  1. Thoroughly clean a pair of sharp pruning shears. Wipe the cutting surfaces with a disinfectant such as alcohol gel hand cleaner. Rubbing alcohol, bleach and water, or nursery products such as Physan can all be used to sterilize pruners. Take your time and leave the sterilizer on the blades. Most sterilizing materials need time to kill disease-causing organisms, so go slowly and let your sterilizer do its job.

  2. Take a good look at the plant to be pruned. Because the new growth will start below any cut you make, you want to plan accordingly. Cutting a few inches off the top is usually not a good idea, as the new growth sprouting off the end of the existing branch will not look quite right.

  3. Instead, plan to cut most branches back by about 1/3 or even more. The new growth that emerges will be strong and will blend in with the rest of the plant.

  4. Choose a long or out of proportion branch to start with. Look about 1/3 of the way down the branch until you find a leaf node (eye) that is facing the direction you want the new branch to grow. Leaf nodes are dormant growth points that sit at the base of every leaf stem (petiole) where it connects to the branch. If the leaf has fallen off, the node will still be there, visible as a small indention or bump along the trunk. Up or out is usually better than down or inward facing but let the plant shape guide you.


  5. To make a new branch grow to the left,
    cut above the node on the left side.
    To make a new branch grow to the right,
    cut above the node on the right side.
    Make the cut just above the eye that you located, leaving about 1/4" (1/2 cm) of wood between the eye and the cut.

  6. If your pruners are sharp, the cut will be smooth and not strip the wood or bark from the stem. Try to avoid doing so if possible.

  7. Move on to the next branch and repeat. Hibiscus are very resilient and will actually grow better after this treatment, so do not hesitate to make those cuts.

  8. Take a final look, as it is still possible to cut the pruned branches even further back if that appears desirable for shaping purposes.


Nodes without leaves ~
any node works for pruning
Choose the node on the side you
want the branch to grow from.
What about branches that grow almost horizontally or, even worse, flop downward? All isn't lost. For such branches you cut 1/4" (1/2 cm) above an upward pointing node close to the main stem as we want to eliminate as much of this undesirable growth as possible. This will cause the plant to grow in the preferred direction.

Sometimes there might be sparsely leafed out areas where we want to see more growth. So we look for a sideways pointing node on one of the surrounding branches that faces toward the direction of the empty spot. This node will grow into a new branch, filling the "hole" in the foliage.

 

How to Hard Prune Old Hibiscus

Sometimes you may have a lack of stem growth on the bottom of a plant. This "caney" look is often a sign of an aging plant. It will not grow new branches without encouragement. This is when you may want to do a hard pruning. It might seem strange that cutting off the upper part of the stems will make the plant branch out lower down but when you do so you change the hormone flow in the plant and it will start branching.

Don't be afraid to cut far down the stem, leaving 3-4 nodes on each main branch, but don't cut closer to the ground than one foot. Be sure to leave some leaves on the plant. After a heavy pruning there should still be a dozen or so healthy green leaves to carry on the photosynthesis the plant needs. This rejuvenating process should not be carried out very often - no more than every 3-5 years. In the intervening years follow the general pruning advice above.

 

How to Prune a Hibiscus Tree Standard


Hibiscus Tree Standards
Many people enjoy the look and convenience of the "tree standard" form of popular ornamental plants such as roses, miniature citrus trees, and even garden variety hibiscus. The look of plants grown this way is neater, perhaps more sophisticated than the look of a typical potted plant. What characterizes such plants is a straight, bare main stem that supports a "head" of branches, leaves, and flowers. Such plants are considered easier to grow than regular bushes since there is less foliage to attract insects, they use less water due to less foliage, and have an all around neater appearance. Prune them a little from time to time to keep the shape of the round "head" and that is about it for routine maintenance. Over time a standard will continue to grow taller, until the 2' plant purchased in a 6" pot will stand 4-6' tall in a 5-10 gallon pot. Standards have been grown since Roman times, and are still as popular as ever.

 

How to Create Your Own Hibiscus Standard
  1. Select a plant that has one straight main stem with a minimum height of two feet.

  2. Cut the top off the main trunk about 2-4" above where you want the "head" of your tree to be.

  3. Cut away all lower side branches close to the main trunk, leaving only branches within 6" from the top of the main stem.

  4. Prune back the remaining branches that will form the "ball" on top of the standard, leaving 2-3 nodes which will grow out.

  5. Continue trimming off new growth as it appears on the main stem. Make the cut flush with the main stem so it will not regrow from that point.

  6. As the top branches grows out, which will take 2-4 months depending on variety, pinch back the tips on the new growth, leaving 2 to 3 nodes on each branch.

  7. Trim off overlong or lopsided growth wherever it occurs to create a round, well shaped crown. By continuing to trim away any new growth on the main stem and pruning the crown, your standard will keep its shape and appeal for a long time to come.

 

Stimulate New Growth

Now that you're finished pruning, give your hibiscus a healthy dose of nutrition, including fertilizer and ideally a good growth enhancer. This will help prevent any shock or distress to the plant due to the pruning, and it will also jump-start new growth at each of the remaining nodes. Keep fertilizing and treating with growth enhancer until your plant is fully leafed out, looking beautiful, and starting to bloom.

 


Pruning a Damaged Hibiscus

Be sure to have plenty of water-free hand cleaner with you because you will need to sterilize your pruners after every cut into damaged wood. Once you start pruning, you'll also need to collect all dead, possibly diseased wood and put it in a plastic trash bag. You want to send all bad wood off to the dump in plastic bags rather than leave it lying around where it can spread disease back to your healthy hibiscus plants.

Checking for Live Wood

First check your plants for dead stems and branches. The test is simple enough. Working from the tip of each plant stem down toward the base, use a strong fingernail or a small knife to make a small scratch test (1/4-1/2 inch long). Scrape away a tiny bit of the brown outer bark of the stem that you are not sure about and look at the color underneath. A live branch will be bright green underneath the bark. If the branch is brown or light tan, it is dead. Some dead stems may be rotten, soft and squishy to the touch. There's no need to do a scratch test on stems that are soft and squishy - they are clearly rotting and dead. Just keep working your way down the stem, doing scratch tests, until you find the point where scratching away the bark reveals bright, healthy, green plant tissue underneath. Plant tissue that is dull green with brown mixed in is not likely to live, so keep moving your way down the branch until you find a bright green patch. Now that we know where the live wood begins, it's time to remove the dead wood.

Removing the Dead Wood - Two Strategies

Hibiscus Pruning
Deeply Pruned Hibiscus Branch
Cut has clean, white wood inside bark.
New growth is sprouting below.
When cutting dead or dying wood from the plant, there are two strategies to choose between. The first is to find the highest spot of clean, live wood on a stem and then cut the stem 1/4 inch above the next visible node down from that spot. This will eliminate the ugly, dead wood and keep any disease from spreading downward. When you make the cut, the inner core of the stem should be clean and white, not streaked with dark stains. If it isn't, then move further down the stem and keep cutting until you find good, clean, white wood. Keep in mind that the stem is likely to branch out from the node nearest the cut or from the 2-3 nodes just below the cut. Sometimes this is just fine, but other times that might make for a funny-looking plant with stems branching out near the top but not the bottom.

The second pruning strategy is to shape the plant while removing the dead wood. You start the same way, by finding the point where the wood is clean, green, and white. Instead of cutting just above the first clean, healthy node, cut is made further down, just above a node that is pointing in the direction you would like a stem to grow. Be sure and cut 1/4 inch above the node, so that there is room for the new stem to sprout. If the cut is too high, the remaining wood above the node may rot. If the cut is too close to the node, you may remove the special plant cells that would have sprouted into the new branch. In this second pruning strategy, you remove more wood than is necessary to eliminate the dead wood. Some of what is removed will be white and clean but the idea is to force more stems to sprout lower down on the bush, to help it achieve a full and attractive appearance. You may cut away as much as 2/3 or even more of a branch in order to do this. Don't be afraid to prune back many of the stems severely. The plant will re-grow with more branches than ever before and look fuller than ever before. More branches mean more flowers, too!

Some of the dead wood on a hibiscus bush will just be twigs. Remove the dead twigs as close to the branch they were growing from as possible without damaging that branch. Throw them in a trash bag in order to dispose of them.

Finding a Suitable Node

Hibiscus Nodes
Hibiscus Nodes
One with a Leaf
So what is a node? A node is a definite bump on the surface of the stem where a leaf has grown or is growing. You can both feel and see it. The best node to choose when cutting is one with a leaf growing from it. If that is not possible due to all the leaves having fallen, don't worry about it. Just choose a node that is pointing in the direction you would like to see a new stem grow in. Usually one pointing outward and upward helps make for an attractive bush. Sometimes, if the plant is too open in appearance, an inward pointing node is best, since it encourages stem growth to fill in the space in the middle of the bush.

You've Pruned, So Now What?

After cleaning up your hibiscus by removing all dead wood and pruning some branches for shape, what do you do? It will take several weeks, depending on weather, before the new growth will come back. During that time keep the hibiscus evenly moist if possible, and fertilize it at half strength once per week. If you notice any insects on the bushes, it is important to get rid of them so that the tender new shoots that are coming will not be damaged by such insects. I was surprised to find spider mites on one of my outdoor hibiscus only a few weeks after we had the freezing nights! You can use forceful water sprays such as with the Bug Blaster or apply Clean Leaf as part of a clean-up program. Applying worm castings or other soil improving materials to pots or ground is a good idea during this time. Growth stimulants such as our Wake-up Spray or Seaweed Concentrate are also excellent to use after pruning.

Hibiscus thrive on attention, and many of the cold-damaged plants from a cold winter will come roaring back to bloom again in the summer if they are given a little tender loving care as they recover from winter. As the temperature warms and summer approaches, increase the fertilizer being used, as well as the amount of water the hibiscus receive. Stay vigilant for insect attack or use routine treatments on the plants as a preventive.


That's it! Pruning hibiscus is not a difficult job, and will produce fantastic results in terms of plant shape, health, and increased blooming. Just follow the simple steps above, and choose the best time of year to do it according to your local weather conditions.