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Propagation
by Brad Thompson

This article will describe the various ways to propagate begonias through cuttings. Rooting cuttings to form new plants is basically a type of cloning. To make new copies of begonia hybrids, cuttings are the only way they can be reproduced. Itís also an easy and quick way to make new plants of begonia species. There are three basic types of begonia propagation; stem cuttings, leaf cuttings, and division.

Propagation involves taking portions of a begonia plant and rooting them to grow into new plants. Some types of propagation require more skill than others or more specialized conditions. Everyone should be able to propagate begonias without too much difficulty. This article contains descriptions and illustrations of the various types of propagation. Nearly all begonias can be started from stem or tip cuttings. Rexes, rhizomatous, tuberous, and a few other types can be started from leaf cuttings or portions of leaves. All begonias can be divided except for some tuberous begonias.

Rooting Mediums and containers

The simplest medium to root cuttings in is water. Nearly all the types of cuttings will root in water, except for leaf section cuttings that require sterile conditions. The best containers for rooting in water are small baby food jars. Whatever container you use should be relatively. The reason for using a small container is that cuttings release a rooting hormone in the water as they root. The least amount of water, the more concentrated the hormone. You can put several cuttings per container. Once roots are half an inch long, they can be potted up in regular potting mix and grown on. Forget any myths youíve heard about water roots, the cuttings will transplant just fine.

Other common mediums for rooting cuttings are perlite and vermiculite or a combination of both. These mediums can be used for cuttings including ones needing sterile conditions. Perlite and vermiculite are rock/mineral products so contain no organic matter that can harbor disease or promote rotting. When using these products, youíre basically still rooting in water. They act as little rock sponges to hold water for the cutting to root in. They also contain air pockets. Perlite and vermiculite donít require sterilization to use, although you do need to use distilled or sterile water to keep it sterile. Vermiculite is less commonly used now, I believe it was determined to contain asbestos. When using either product, you should wear a mask or avoid breathing in the dust when mixing or pouring it.

Another medium for rooting is peat moss or various combos of peat moss, perlite, and vermiculite. This works for all types of cuttings but unless sterilized for sure, it may rot cuttings since it contains organic material. It is mostly used for stem cuttings or rhizome cuttings that donít require sterile or specialized conditions. Itís also used for cuttings that are overly fleshy and tend to rot in water only.

Many begonia cuttings can be started directly in your potting mix in a shady location. Most rhizome, shrub, thick-stemmed and canes will start directly in mix. You should only use this method for the sturdier varieties though.

There are many clear containers such as sweater boxes that work quite well for rooting begonia cuttings. Leaf and wedge cuttings require some type of container to root in. It has two benefits. It keeps the humidity up so the rooting medium doesnít dry out and is less stress on the cuttings. It also keeps spores that cause disease from your medium.


Tip and Stem Cuttings

 A tip cutting has to have certain elements in order to grow a good plant from it. As a general rule, begonias wonít send out new growth from a node where they have previously had a bloom. Nearly all begonias that wonít grow from leaves also wonít send out growth from a node they bloomed at. This element doesnít apply to tuberous, rhizomatous and rexes, they will send out new growth from any rooted part of the plant.

The illustration at the left shows a typical begonia stem and its various possible components. On a begonia stem, there is a node above each leaf. This node can have a bud that will grow into a new stem someday, it can have a flower cluster grow from it, or it can be dormant and not showing a bud. Any node that doesnít have flowers or the scar left after the flowers have fallen off, has a bud in that node whether it shows or is completely dormant and not showing in the lowest node will be a good cutting.

A good cutting needs to have a node with a bud on it for it to grow into a proper plant after itís rooted and In the illustration you can see that the planted. The bud is where all future basal growth will lowest node pictured has a scar from where come from as the cutting grows. Using cuttings where the leaf was attached. It also has a bud. the nodes have had blooms will result in plants that can That is the main requirement of a good never send up new basal growth. The illustration cutting, no matter what the rest of the shows how to determine what nodes you have. If you nodes on the cutting, look at a node and there is a leaf or the scar left after a leaf has fallen off, and there is no scar left from a .A tip cutting should also have at least a flower, then there is a growth bud there whether you couple leaves. One without leaves may can see it or not. When leaves and flowers fall off they root but not as easily or as quickly. You both leave round scars on the stem where they were. can also make a regular stem cutting from So, a bare node that has two scars is a node that parts of a stem that donít have the tip. For previously had a leaf and a flower cluster. If this those types of cuttings, since they donít explanation isnít clear, the illustration on this and the have the tip, need to have at least two next page should make it clearer for you. One at the base of the cutting that will be buried in the potting

The best cuttings are ones that have never bloomed mix and one to grow into top growth. It since they have buds in all their nodes that will should also have a leaf if possible. Woody eventually grow into new stems and new side growth. hardened stems will root without leaves Any stem cutting though, that has at least one good bud however. They do take longer though.

The illustration at the right shows a good tip cutting. Elements of a good tip cutting It has buds in the leaf nodes for future stem growth as described previously. When taking a tip or stem cutting cut the stem about half an inch below the selected node. Itís possible that if you have any stem rot while rooting the cutting, if you have cut closer than half an inch below, you could lose that lower node. Half an inch gives you some margin. Cutting further than half an inch below leaves too much unnecessary stem below the lowest bud. When you get ready to pot up the cutting after it roots, it will be hard to get that lowest bud buried in the potting mix if too much extra stem is left below it. When rooting the cutting, you should remove any leaves from the lower nodes first, since those parts will be buried eventually anyway can could rot.

In the illustration below right you can see how to pot up the newly rooted cutting. Put the cutting as low in the pot as possible covering at least one good bud. In the illustration, you can see the importance for doing this. The buried buds will eventually grow into new shoots and all the future basal growth. Without a buried bud, the cutting will of course still root and grow. It wonít be able to send up new basal growth however. It will only be able to branch somewhere above the pot.

The only time you should use cuttings without buds to bury is if youíre going to grow a begonia as a standard. Since a standard should be just one main stem, ordinarily bad cuttings are perfect for that purpose.

For begonias that are everblooming and hard to get good cuttings from, one tip is to first prune the plant. Then take cuttings from the new growth comes up.

Rhizome Cuttings

Rhizome cuttings are a type of stem cutting. Unlike cane, shrub and other stem cuttings however, you donít have to worry about nodes or bloom scars. Rhizome cuttings can be made any length. In the illustration above the rhizome is cut into two inch sections. Most rhizomes can be rooted directly into your potting mix without any special considerations. The rhizome is fleshy and can easily maintain itself until roots and leaves form. Some more delicate varieties such as rexes may do better if rooted in an enclosed container though. Long rhizomes can even be rooted in water like you would any stem cutting. They are slightly more prone to rotting in water though since they are so fleshy. Although leaf cuttings on rhizomatous types will give you more plants in the long run, rhizome cuttings will give you a new plant faster. Itís a good method for those that just want another plant or two and arenít worried about producing larger numbers of plants. The rhizomes donít have to have leaves to root and grow. When using the tips of rhizomes remove the largest leaves, theyíll probably fall off during rooting anyway. Make sure the rhizome has good contact with the rooting medium but not buried more than half way. Tip cuttings from rhizomes can be rooted upright with the cut end stuck one half to one inch into the rooting medium.

Leaf and Wedge cuttings

Many types of begonias will start from leaf cuttings. These are mainly rhizomatous, rexes, and tuberous begonias. With nearly all begonias you can root a leaf, but only certain types will then send up a new plant from the rooted leaf. With begonias other than the three types mentioned, consult with other growers about specific plants that may start from a leaf. Exceptions to the only rhizomatous and tuberous starting from leaves rule, are begonias such as B. luxurians and some of the mallet type canes.

Types of leaf cuttings

All parts of the leaf are capable of rooting and forming a new plant. The only requirement is that the leaf portion contain a main vein. There are three main types of leaf cuttings. A full leaf cutting, wedge cuttings, and cone cuttings. If your purpose is to create a number of plants, you may choose to do wedge cuttings since you can make many wedges from a single leaf. If your purpose is just to propagate a couple of new plants for yourself, you may choose to just use whole leaf cuttings. Cone cuttings are slower than regular whole leaf cuttings but since more veins are exposed to the rooting medium, the resulting plant is much fuller.
Materials required

There are several basic requirements needed for starting leaf cuttings. You need warmth, good light, humidity, and a sterile moist medium.
Light and warmth

This is best provided by using fluorescent lights. A light stand, besides providing constant good light, also provides suitable warmth. Any area you can keep reasonably warm will work however. If not using lights, you need an area with bright light but no sun. Since leaves need to be rooted in covered containers, any sun will overheat and cook the cuttings. Under lights, you can keep the lights as close to the top of the container as possible. Leave the lights on for at least 14 hours a day. You can leave them on continuously if desired.

Containers

Most leaf cuttings need covered containers to root in. The purpose is to keep the humidity high and also to keep the medium sterile. The container can be as simple as a clear plastic cup covered with saran wrap for single cuttings or an expensive tray with a clear dome. You can even root leaf cuttings in zip lock bags. If youíre lucky enough to have a greenhouse, you can root leaf cuttings out in the open under a misting system. Even in a greenhouse though, you may choose to use covered containers for ease of use.

I know several growers that root in zip lock bags with individual bags for each cutting. One grower I know stapled the bags to the wall in out of way places during warm weather. For especially rare or hard to grow varieties, I usually do provide those cuttings their own container. I put the rooting medium in a small pot then put the pot into a zip lock bag after the cutting is in it.

Trays with domes or clear sweater boxes work very well. You can even use aquariums left over from your fish experiments. There are also a myriad of different clear sandwich or food containers to choose from.

You can either use the medium directly in the tray or use individual pots of medium for each cutting then set in the tray. Both have advantages and disadvantages. Just filling the tray with medium is easier and can be refilled over and over. However, in my experience if you root this way you end up with parts of the tray and different varieties of begonias growing at different rates. You usually end up with half of the tray potted up already and the rest still waiting. If you propagate continuous and keep refilling the tray as you take things out, it will work fine though. Another disadvantage is getting or keeping the medium to the correct dampness without being too wet. Itís also hard to keep the cuttings separated by variety as they grow unless youíre careful to make clear separations and labeling.

Using individual small pots for each cutting works well because you can move cuttings from box to box as needed. If youíre using several boxes as things get potted up, you can recombine the slower rooting cuttings into one box. The disadvantage is that it is more time consuming filling all the individual pots and making separate labels for each. If you donít mind the added time, itís the better method though.

Rooting mediums for leaf cuttings

The most commonly used medium for leaf cuttings is perlite. It is already sterile and holds the correct moisture without staying too wet. Its only disadvantage is you have to check often to make sure it doesnít dry out. Any medium such as peat moss, vermiculite and combos will work fine as long as they are made or kept sterile and kept to the right degree of moisture. I have used all the various mediums with good success but find perlite the easiest and best to use.

Another less common medium for rooting cuttings is called Oasis(TM). This is similar to the Oasis used for floral arranging but comes in form specifically for rooting cuttings in. It is made a size to fit the most common tray size. It has individual one inch cubes with a hole in the center of each to insert the cutting in. The Oasis can be cut easily to fit any container though. Donít try using the floral Oasis for this purpose, it isnít made for rooting cuttings like this other product is. The oasis is soaked in water till it has soaked up as much water as it can, then drained. It already contains fertilizer so nothing needs to be added to the water. Itís already sterile so also doesnít need to have anything extra done to sterilize it. I have used it successfully many times and it works especially well for wedge and small cuttings. It was designed so that after the cuttings are rooted you cut the cubes apart and plant the cube and all in your potting mix. This design however doesnít work for begonias. If the cube is left on the cutting the plant will usually not thrive or die later. The cube either wicks water to the surface of the mix so causes a dry spot, or stays too wet and causes the plant to rot later. Examination of the roots on plants that failed showed that the roots all stayed in the oasis instead of growing out of it into the mix. For this reason, you must remove all the Oasis from the rooted cutting before potting them up. This usually results in some root loss, besides being time consuming. However it is easy to use so does have its uses for some growers.

Other items youíll need

One item youíll need is something to cut the leaves with. You can use a knife, scissors, or pruners. The best cutting tool to use is a razor blade. There are several reasons. Using a new blade means you have a sterile utensil that doesnít have diseases from your plants outside. If you use your pruners, youíd have to sterilize them. The main reason though is because it makes a very clean precise cut. If you use scissors or pruners they donít cut cleanly and crush the edges of the cutting. This makes the cutting less able to draw up water. Using the razor blade cuts cleanly without crushing cells along the edge.

Youíll also need something to sterilize the cuttings with. It doesnít matter how sterile your medium is if the cuttings you put into have spores of disease on the leaf surface. The most common disinfectant for using on cuttings is a five percent bleach solution. I have also heard of using a peroxide solution but havenít personally tried that. I have also sterilized cuttings by dipping them in a fungicide mixed to the recommended strength on the bottle. I let them dry, then rinse with water before using. Make sure to wear gloves. You can also use Physan(TM) following the directions on the bottle. I usually spray my tray of cuttings with a fungicide after they are done just to make sure nothing was missed.

Whole Leaf Cuttings

A whole leaf cutting consists of a leaf with a portion of the leaf petiole (a petiole is the stem-like structure that holds a leaf to the plant stem). You should leave the petiole about one half to one inch long for rooting. When taking the cuttings leave the petiole long until just before youíre ready to put it in the medium so that the cut is fresh. Leaving the petiole too long wonít hurt anything. However, it will take longer for the plantlets to come up after rooting since theyíll have to come up from deeper in the medium.

In the illustration on this page you can see a whole leaf. The best leaf cuttings are young leaves but any leaf will work such as damaged leaves you have to remove anyway. If the leaf is small you can just cut the petiole and insert it into the rooting medium. Larger or damaged leaves you should cut down as in the illustration leaving a round center of the leaf with the petiole. The remaining part of the leaf can be discarded or used for wedges. The reasons for cutting the leaf down is that it takes up less space in the tray and because the petiole will have less leaf to support. The cut down leaf will have less leaf surface to transpire from so the petiole wonít have to provide so much water. Even if making wedges or cone cuttings, save that middle portion as an extra cutting. On difficult varieties, that portion will usually root, even if your wedges fail.

Whole leaf cuttings can be started without enclosed containers for some of the sturdier varieties. You can leave the petiole slightly longer and root them in small jars of water. You can also fill the small jar with perlite and add water. The second method does support the leaf better. You can also use pots of perlite set in a shallow tray of water. If you use any of these methods, donít cover the container since the cuttings will usually rot with all that water if covered. It does take practice and experience to find out which varieties of begonias will work with which methods.
Wedge Cuttings

Wedge cuttings are the easiest way to start many plants at a time with the least plant material. Itís especially useful for rare begonias or begonias that only have a couple good leaves to use. In the illustration you can see how to cut a leaf into wedges. A wedge is simply a portion of leaf with a vein in it. You can make your wedges as small or as large as you like. Smaller wedges may not survive if your conditions are less than perfect. I usually make my wedges about an inch or inch and a half long.

For wedges, conditions must be as sterile as possible. As stated earlier in this chapter, a razor blade is the best utensil to use for cutting. Perlite is the best medium for rooting wedges. Add a very slight amount of fertilizer so the plantlets have some food when they start to grow. You can fill a tray with perlite and premoisten. When perlite is wet it becomes very solid. I use a knife or plant label to make rows of small slits in the perlite the right size to fit my wedges. The wedges can be touching or overlapping so donít be afraid to pack them closely. Usually about half an inch to and inch apart works well. Try to insert the wedge as upright as possible. Also make sure to label carefully and keep different varieties separated. Try to mix the tray up so that varieties that arenít a similar color arenít next to each other so they donít get confused later. They do require a covered container.

Wedges may take a couple months to form roots and plantlets. Check the moisture of the medium regularly to make sure it doesnít dry out. Misting occasionally with a weak fertilizer for foliar feeding will help them along. You may want to leave the cover opened slightly till they dry off a little before closing tightly. Using distilled water will make sure that you donít introduce any diseases into your sterile environment.

As soon as little plantlets have come up and are large enough to handle they can be potted up individually into small pots. The illustration at the top of this pages shows the new plantlets coming up from a leaf cutting and wedge cutting. For the first transplant they should remain in a covered container. Treat them as you would seedlings of the same size. Once they have filled the small pot and are ready to transplant again, you can harden them off and move to other locations.

Cone Cuttings

Cone cuttings are similar to wedge cuttings. You cut the center portion out of the leaf but instead of cutting it into sections, you leaf it whole. You wind it around to form a cone and insert into your rooting medium. Make sure to also put some medium inside the cone. On the next page are illustrations showing how to do this.

The advantage to cone cuttings is the full plants you can get from this type cutting. Plantlets will come up from all the vein ends along the bottom of the cone resulting in dozens of shoots. If left together, they quickly grow into one full plant. They can also be separated or cut apart to make many smaller plants after rooted and plantlets have formed.

On all the various leaf cuttings discussed in this chapter after plantlets have formed you can either pot up the cutting along with the plantlet or you can remove the plantlet and use the cutting over again. Some cuttings will send up plantlets several times before they run out of energy if reused.

Mallet and Heel Cuttings

 
These types of cuttings are not commonly used but they do have purposes. There isnít much difference between the two and the mallet has less chance of errors or rotting so you shouldnít use the heel version unless you have a specific purpose.

A mallet cutting will allow you to make a type of leaf cutting from plants that ordinarily wonít start from leaves. Since the leaf cutting contains a portion of the stem with a growth bud it can be used for any type of begonia. Itís mostly useful for creating as many plants as possible of a certain variety. Say you have a cane with one stem that has several nodes with good buds. If you propagate by stem cuttings you might only get one or two cuttings. By using mallet cuttings you may get a dozen, depending on how many nodes and leaves there were. Varieties of canes that drop their leaves easily may not be good candidates because the leaf may separate from the stem before the mallet roots. Treat mallet cuttings as you would whole leaf cuttings following the same procedures. After rooting a shoot will grow from the bud on the cutting.


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