Hibiscus species can be propagated from their seeds and the new plants are generally true to the parent plants. While some species self seed efficiently, it is possible to propagate the plants in this way. However, the time consumed from the day of sowing the seeds to develop into a lush green, shapely flowering bush is much longer compared to propagating hibiscus from wood cuttings.
Hybrids are entirely different from the species and it is not possible to propagate them from their seed and still produce offsprings identical to their parents. This is mainly owing to the fact that the complexity of the hybrid parents always results in inconsistent seeds. There may be occasions when some seeds will revert to any one of the parent, while others may be relapsing to an earlier ancestor or may be still different. In fact, the chances of the offsprings to resemble their parent plants are somewhat less.
It is possible speed up the germination process even when you are propagating hibiscus species from seeds. Although it is not necessary, just scrape the surface of the seeds using a razor blade before sowing it. This will hasten the germination process. At the same time, you may use commercially available starter mix and sow the seeds in a shallow container. Place just a couple of seeds into the starter mix to a depth of approximately the same as the size of the seeds. Subsequently, water the seeds properly. Position them in a place beyond direct sunlight and at a temperature of about anything between 68°F and 77°F (20°C and 25°C ). Ensure that the potting medium always remains moist, but not soggy. New seedling will emerge about two weeks from the date of sowing and the shoots too will develop gradually. You can plant the seedlings in separate pots when they have grown up to a height of about 8 inches (20 cm). It will take another 5 months to 12 months, or may be a little longer, for the plants to bloom.
Hibiscus can be propagated by several other methods, including tip cuttings, grafting, wood cuttings, hardwood cuttings, air-layering and tissue culture. However, using these means to propagate hibiscus requires some expertise so it is preferable to leave these techniques to specialists, while amateur gardeners can propagate hibiscus by simpler methods discussed above. For instance, tissue culture is a very contemporary means to mass production of new plants and this process can only be undertaken in laboratories.
Generally, tip cuttings are made during summer when the plant is growing vigorously. In fact, it is very important to handle these cuttings properly for developing new plants from them successfully. It is advisable not to take a large amount of tip cuttings and soak them in water for a prolonged period. What you need to do is just immerse these tip cuttings in a solution comprising water and Formula 20 for only about a minute and subsequently place them in a plastic bag after sprinkling some water in the bag or wrap them with a moist cloth. Ensure that the tip cuttings are not exposed to sunlight, or they will wilt.
Ideally, each tip cutting should be about 10 cm to 15 cm (4 inches to 6 inches) in length. Be careful to cut the tips at an angle of roughly 45 degrees through an eye or bud. In fact, you will find an "eye" at the base of every leaf. Immerse these cuttings in a hormonal rooting powder that is appropriate for softwood cuttings and subsequently position the tip cuttings in the commercially available or home made rooting medium. In fact, the rooting medium can vary greatly. While some use perlite and peat, there are others who make use of coarse river sand. You may also use a mixture of perlite, peat and sand, or vermiculite and peat as the rooting medium. In case the leaf is large, reduce the leaf area by 50 percent.
The cuttings will perform better provided they are placed in individual propagation tubes. However, you may also place a number of tip cuttings in the same pot. If possible, you should place the tip cuttings in glasshouses equipped with misting appliances. If you are a home gardener, place the tip cuttings in a small frame enveloped with a transparent plastic. However, you need to sprinkle the new plants may times all through the day with a view to put off too much transpiration.
Medium wood cuttings are undertaken during autumn, just when the softwood starts maturing. Such cuttings are mostly taken by nursery people who desire to amass a stock of a specific hibiscus variety. In fact, home gardeners seldom prefer medium wood cuttings, as this deprives the plants of their blooming wood. In addition, such cuttings take a long time to establish themselves - usually they do not establish completely before the arrival of the cooler weather. Usually, nurserymen select firm wood a little smaller compared to the thickness of a pencil and do away with the top three leaves from the cutting. The cuttings are subsequently reduced to about half and a cut is made diagonally through the eye roughly 7.5 cm (3 inches) just beneath the leaf axil. Subsequently, immerse the cutting into a medium wood cutting hormone powder (for instance Seradix No. 2) and then plant the cuttings into individual propagation tubes containing the rooting medium. Place these tubes under a glass cover or any similar thing. Allow the cuttings to establish themselves and plant them in individual pots only in the next spring.
All said and done, the simplest method of propagating hibiscus is by cutting hardwood from the plants at the end of winter in your region or at the onset of spring. As this period of the year is also the normal time for pruning the plants, there is no reason why you will not be having an abundant supply of wood. Before you undertake this method of propagating hibiscus, ensure that you have a cold frame and a provisional glasshouse ready for shielding the hardwood cuttings from gusts of wind. In addition, the glasshouse and cold frame will also prevent the cuttings from becoming dehydrated and, at the same time, provide the cuttings with additional warmth needed to support root growth.
Opt for robust, erect wood having the thickness of a pencil, but a little larger compared to it. If you select weak and twisted stems, they will eventually produce similar plants. Therefore, remember the better the wood, the more robust and good the plants will be. Bend the cut hardwood backwards against the stem to get rid of all leaves or remove the leaves using sharp secateurs. However, be careful not to tug or pull the leaves even if they are somewhat dry, as this may strip the stem, pull out the eyes (buds), and rip the bark. Then make a cut at roughly 45 degrees angle using a knife through an eye at the bottom of the cutting.
When you have made the cutting, trim it to a maximum length of anything between 12.5 cm and 15 cm (5 inches and 6 inches). Then place these hardwood cuttings in separate propagating tubes or in community pots measuring 15 cm (6 inches). Each community pot can accommodate approximately 30 such cuttings. It has been found that hardwood cuttings have a preference for coarse river sand mixed with some amount of peat as their rooting medium. Nevertheless, you may also use other rooting mixes, including perlite, peat and sand or peat and perlite. All these have proved to be successful rooting mediums.
When the hardwood cuttings have developed roots, remove them from the propagating tubes or community pots and plant them into larger containers. Use a mixture comprising two parts sandy loam, one part peat, one part coarse sand and one part leaf mould and one part mature cow fine manure. Before potting the rooted cuttings, place them in separate buckets containing clear water. This will help to prevent any damage to the roots while transferring the cuttings from the community pots to larger independent containers. After planting them in large separate containers, ensure that you water the rooted cuttings regularly using a solution of Formula 20 and water. Prior to planting, dip the rooted cuttings in a hormone powder - if possible use a medium wood or hard wood kind of hormone powder, such as Seradix No. 2 or Seradix No. 3. Majority of gardeners plant their cuttings quite deep into the mix. It is advisable that you position them to a depth of anything between 2.5 cm and 3.7 cm (1 inch to 1.5 inches) into the rooting medium.
Several different kinds of propagating units are available and these will be useful for home gardeners to strike the cuttings as well as raising seeds. If you buy any of these propagating units, you will be ensured of further success while propagating hibiscus and, at the same time, make you delightful watching your favourite plants growing as well as maturing to produce attractive flowers.
The grafting technique is used for two purposes - augment the count of plants from a current hibiscus variety or to create a weak growing hibiscus variety on roots that are more vigorous. Cuttings having wood measuring roughly the diameter of a pencil are taken from any sturdy rootstock like "Albo Lacinatus" (also called "Ruth Wilcox") or H. amottianus (also known as "Wilder's White") and they are grown in separate pots to produce robust and strong plants. When this under stock is provided with ample soluble fertilizer about a week prior to grafting, it will speed up the growth of the graft.
When you are selecting hibiscus rootstock for grafting purpose, it is advisable that you avoid species such as H. schizopetalus that grow very tall and akin to a whip. The girth of these species is small and, hence, scions that are grafted on them will have a larger diameter compared to the stock. In other words, these will produce weak grafts. It has been found that other different under stocks are more appropriate for grafting in places having different climatic conditions. For example, many hibiscus growers use "Pride of Hankins" (also known as 'Landersii') or the "The President" more in their areas compared to "Albo Lacinatus". On the other hand, some prefer using "Albo Lacinatus" to "Pride of Hankins" or the "The President". Therefore, it is suggested that before undertaking grafting one should undertake a small research with the older hibiscus types in their respective areas and then choose the variety that is hardiest, strongest and most vigorous as well as resistant to diseases - especially resilient to root rots. Following a study of the local older hibiscus types you will find some varieties that can be used successful in the form of an under stock.
Grafting techniques that are used most widely include the tip graft, side graft and veneer graft. The variety that is actually grafted to the under stock or root is known as a scion. This particular wood section is cut into small portions, each having at least two to three eyes revealing the green hued buds.
In case the color of the buds is brown and they are latent, the scion will take a longer time to grow. You need to bear in mind that the bud on the lowest part of the scion ought to fit near to the rootstock so that it produces an erect plant with a proper shape. You can achieve this by covering it with a plastic bag till the graft establishes itself and by keeping the graft in a shaded place. It is also important to shield the plant from wind as well as protect it from becoming dehydrated till the buds develop into leaves. You will notice a tissue, similar to the scar tissue in animals, forming over the graft's cut surfaces in just two to four weeks' time, provided the rootstock grows vigorously. It is best if you allow the grafting tape to remain for anything between six and eight weeks. However, at the same time, you should get rid of any other binding that is stronger as this will avoid strangulating the graft. When the graft has established itself well and produced several leaves, you may cut out the leaves as well as the eyes of the rootstock. Remember to attach a tag to the plant bearing the scion's name and the date when you undertook the grafting. This is important for identifying the plant as well as maintaining records.
It is interesting to note that several hibiscus growers actually wax the grafts with a view to stop them from becoming desiccated. For this, you may use either grafting tar (Colgraft or Emastak) or grafting wax. Make us of a small paint brush to apply the grafting wax to the whole graft, thereby sealing the graft absolutely. However, be careful not to remove the wax because it will come off when you get rid of the grafting tape. If you are using the grafting tar, you should completely seal the part where the rootstock and scion are joined as well as the cut area on the scion. Remember, you should never coat the eyes or buds with the grafting wax or grafting tar.
In fact, whether the grafting process will be a success or not, entirely depends on the skill of the grower or the "feel" in the process. Actually, some amount of practice is necessary to have this feel and one becomes proficient in the process as they undertake more and more grafting. It is very normal that you will not be perfect when you undertake grafting for the very first time, but you will certainly improve with each grafting that you undertake later on. The best way to master the technique is to save a branch while pruning your hibiscus and practice your skills on it. Make on angled cut after another till your cuttings are even and regular that will perfectly match on the sides. Be careful so that you don't cut your fingers while practising.
You need a very sharp and clean knife for grafting. So, the first thing is to acquire the best quality you can get - one made from superior quality steel and having an edge. You will find various types of special knives, especially meant for grafting, from different manufacturers. Knives made by Kunde are among the best for the purpose. Keep the knife clean as well as sharp and protect the edge of the knife from coming in contact with any other tool. Also ensure that you use the knife exclusively for cutting plant materials. When the knife is not in use for a long time, apply a thin coating of Vaseline or oil to the blade.
Learning how to maintain the knife as well as whetting it using an excellent carborundum stone with fine grain is very important. Remember, knives used for grafting should only be sharpened on one side - depending on whether a person is right-handed or left-handed. Place the blade more or less flat on the carborundum stone and whet it against the edge in a manner as if you are slicing the stone - pressing the blade and moving it towards yourself at an angle of approximately 30 degrees. However, a number of people choose moving the blade in a circular path on the carborundum stone. Be cautious to keep the stone's surface absolutely even and smooth. Get rid of all burs by means of stropping the blade on leather or an exceptionally fine emery paper. Acids and fibers present in plant tissues gradually wear away and oxidize the knife's fine edge. Hence, from time to time, you need initiate measures to stop this from happening. It is also advisable that you keep a raw potato at hand and run the knife's edge through it from time to time to keep the knife clean and help it to remain sharp for a longer period.
The grafting knife should be sharp enough to cut through the sinewy fibers of the plant's wood even at small angles, without tearing or bruising the plant. Moreover, the edge of the knife should also be sufficiently keen to make even cuts which perfectly match with a smooth contact between the two surfaces at the cutting. You may also use the popular utility knives that are available with interchangeable blades, provided you take adequate care, as they are extremely sharp. Although such knives are usually weighty and cumbersome, you can use them proficiently with enough practice, just like the usual knives. It only takes a few seconds to change the blades of these knives, but they certainly ensure that your knife has a sharp edge always. It is recommended that you try to stick with a reputed brand like Stanley, because many manufactures make blades from poor quality steel and they usually have inferior cutting edges.
While undertaking grafting of hibiscus or any other plant, always ensure that the thickness of the graft matches with that of the under stock. While this may not be possible all the times and conforming the two sides of the cambium layers is also not essential, it is sufficient to just match one cambium layer. However, the results will definitely be better when both sides are matched. Precisely speaking, the cambium layer is the tender green tissue stratum found between the bark and the white wood of the stem. Be careful not to touch the cut surfaces with your fingers. Match them carefully and tie them firmly using a plastic grafting tape. At times you may also use twisters instead of the plastic grafting tape. It is important that the graft union heals rapidly as this will enable the buds of the graft to draw water as well as nutrients from the rootstock when they start sprouting.
This particular technique of propagating hibiscus helps to get larger plants within a very short period. The ideal time to undertake the air-layering method is warm weather. This method involves completely strapping straight growing branches, making two cuts at a distance of roughly 2.5 cm (1 inch) from each other. At the same time, the bark of the branch as well as its green cambium is completely removed up to its white wood. You may apply a hormone rooting powder to the upper portion of the cut.
Rinse the cut branch with plain water and immerse it in sphagnum moss for some time. Subsequently compress some properly soaked sphagnum moss and make it somewhat dry. Swathe the moss around the area where the cut has been made, cover the place with a plastic and wrap it with a aluminium foil sheet measuring about 15 cm X 15 cm. If you want, you may additionally cover the area with a brown paper layer and tie them firmly. While the plastic sheet and aluminium foil will help to conserve the moisture, the brown paper layer will help to prevent exposure to light and, at the same time, put off birds from pecking holes into the place and, thereby allow the moss to become dehydrated.
Following examinations when it is found that the cut portion has developed an excellent root ball, the branch is severed just below the ball. Subsequently, you should remove the plastic sheet and aluminium foil with care, ensuring that you do not disturb the root or moss covering in any way. Remember, you should not get rid of the moss. Then the branch's other end is trimmed very close to the root ball, and placed in a solution of water and Formula 20, possibly in a clean bucket. Let the new plant be soaked in the solution and then plant it in a separate pot. Water the plant carefully and regularly. Preferably you should trim a few leaves of the new plant and provide it adequate protection from sun and wind till it establishes itself properly. For best growth, keep the potted air-layer in semi-shade for about two to three weeks. Fertilize after 30 days and see it flourish.