Propagating Roses
Johnny, Mary, Sue, and Carl all have methods for rooting roses. Each claims that theirs works best and has the highest success rate. You try the different methods and get little or no results -- why? Are you just a bad propagator? In a poor location? Why won't these methods that seem to work for other folks, work for you?
Techniques, when rooting roses (or any other plant material), are often blindly followed without a true understanding of why this or that procedure works. The information contained within this article seeks to clear up the matter for the novice and clarify the issue for the more experienced. It is an understanding of biological plant traits that will lead to successful rose cuttings.
Plants need three things in order to grow: roots, shoots (stems) and leaves. When you take a cutting, you have essentially removed the root area from that piece of plant material and it can no longer take up the water and nutrients that it needs. Plants, though, have a mechanism for regenerating lost portions of themselves. This is known as adventitious growth. The technical definition for this term is: a stem, leaf, or root that arises from an "unexpected" location. In the case of rose cuttings -- from the bottom of the stem.
Imagine trying to re-grow a part of yourself -- like a chameleon that has lost a tail. Such an endeavor takes an enormous amount of energy and hormonal production. Roses are no different.
During the re-growth phase, plants must have the following things in order to survive the process itself:
Now for a brief summation of the above factors and a few methods of creating the proper situation for each:
Auxins
Many roses contain plenty of these hormones necessary for re-growth. However, we can aid in their endeavor by supplying a little extra boost. Most of you have heard of rooting powders, but you don't understand how they work or the proper method of application. This is probably the most misunderstood of all the processes listed above. Some folks will tell you to scratch the lower surface of the cutting and dip it in hormone; others will say to just dip it and don't scratch; still others will tell you to slice off a piece of the surface area at the lower part of the cutting and then apply the hormone. Few, (if any) can explain "why" they are doing this in the first place! Which one of these procedures is "correct?" In actuality, none of these procedures will give you the best results. "scoring" or "wounding," as the propagation textbook describes it, does not mean "gouging" the stem. Using powders is also not the preferred method.
Addressing the issue of scoring, it helps to know a little about the biology of plants. Since it is from the cambium layer of plants that the new roots arise, damaging that layer will not be conducive to root initiation. Cells of the cambium layer are easily crushed/destroyed by improper technique. Instead of scraping, gouging or dicing the tissue, one should be slicing into the stem (gently) with a SHARP, STERILE blade. I prefer a razor, usually in the form of an "exacto" blade -- a tool of the artist's trade that has a nice handle and very sharp, replaceable blades. Slicing does not harm the cambium layer to any great extent and creates an opening that is accessible to the rooting hormone. Which brings me to the next point: use a liquid hormone, not a powder when treating your plant stems. The recommended formulation should contain both indolebutyric acid (IBA) and naphthaleneacetic acid (NAA) in relatively equal amounts. One such product that seems to work well is Dip 'N Grow which can be found in several gardening catalogs. The reason for the use of liquids? The solution immediately goes into the stem tissue, allowing for the best use of the hormone in the place that will actually be able to use it. By their very nature, powders, (for obvious reasons) will not give you the same results. Callusing (necessary before root initiation occurs) will appear to almost burst forth from the area that has been sliced. Strong, thick roots are usually seen within four to ten days after the cuttings have been stuck.
Humidity, Bright Light and Warmth
In order for the cutting to generate the energy needed for root initiation, it must continue to carry on photosynthesis. The few leaves that have been left attached will work to supply the necessary food for this. However, without a root system, they have no method of water uptake -- hence the need for 100% humidity (i.e., plastic bags, mist systems, etc.). Bright, filtered light is also necessary for the production of chlorophyll. However, if the light is too intense the cutting will only be working toward staying alive, not in root regeneration. Too little light limits chlorophyll production, and therefore the energy needed to create the new root system. Possible methods for lighting: bright interior window, grow lights, dappled shade under a tree and greenhouses with a shade cloth, to name but a few. Cold and extreme heat will cause most plants to become dormant. Obviously, a dormant plant is not going to be initiating a great deal of root growth. Stressing a cutting with temperature extremes is a sure-fire way of killing it. Either attempt cuttings when the temperatures are relatively moderate or use a climate-controlled facility (greenhouse or inside the home).
Sterile Soil/Medium
Any medium will work if it is well drained and sterile. Some contain nutrients or can easily hold them, while others are nothing more than a place for roots to grow. Too much water contained in the medium will cause rotting of the cutting; non-sterile soil will decrease the take rate due to the pathogenic elements present and dry soil will be of no use at all The medium should be moist, but not sopping wet or totally dry. Personally, I prefer to saturate and stir my medium (when using a soil-type material) and let it drain awhile before using. Recently, I've started using Oasis trays/cubes for cuttings for ease and space retention.
As you can see, I've given you a few hints on how to provide (for your cuttings) the basic essentials needed for root regeneration. Don't feel that my "technique" is the only way, it is merely the methodology that works for my particular situation. Take what is shown above and develop your own technique. That's what makes being a rosarian so much fun -- being adventurous and trying new things.
Techniques, when rooting roses (or any other plant material), are often blindly followed without a true understanding of why this or that procedure works. The information contained within this article seeks to clear up the matter for the novice and clarify the issue for the more experienced. It is an understanding of biological plant traits that will lead to successful rose cuttings.
Plants need three things in order to grow: roots, shoots (stems) and leaves. When you take a cutting, you have essentially removed the root area from that piece of plant material and it can no longer take up the water and nutrients that it needs. Plants, though, have a mechanism for regenerating lost portions of themselves. This is known as adventitious growth. The technical definition for this term is: a stem, leaf, or root that arises from an "unexpected" location. In the case of rose cuttings -- from the bottom of the stem.
Imagine trying to re-grow a part of yourself -- like a chameleon that has lost a tail. Such an endeavor takes an enormous amount of energy and hormonal production. Roses are no different.
During the re-growth phase, plants must have the following things in order to survive the process itself:
- necessary auxins (growth hormones)
- 100% humidity (remember, there is virtually no water uptake and it is necessary for photosynthesis)
- sterile soil/medium (cuttings are extremely vulnerable to fungal attack)
- bright light (remember, they need the energy from photosynthesis to create the new roots)
- and warmth (too hot and they can't keep the moisture content up, too cold and the process slows down and invites rotting)
Now for a brief summation of the above factors and a few methods of creating the proper situation for each:
Auxins
Many roses contain plenty of these hormones necessary for re-growth. However, we can aid in their endeavor by supplying a little extra boost. Most of you have heard of rooting powders, but you don't understand how they work or the proper method of application. This is probably the most misunderstood of all the processes listed above. Some folks will tell you to scratch the lower surface of the cutting and dip it in hormone; others will say to just dip it and don't scratch; still others will tell you to slice off a piece of the surface area at the lower part of the cutting and then apply the hormone. Few, (if any) can explain "why" they are doing this in the first place! Which one of these procedures is "correct?" In actuality, none of these procedures will give you the best results. "scoring" or "wounding," as the propagation textbook describes it, does not mean "gouging" the stem. Using powders is also not the preferred method.
Addressing the issue of scoring, it helps to know a little about the biology of plants. Since it is from the cambium layer of plants that the new roots arise, damaging that layer will not be conducive to root initiation. Cells of the cambium layer are easily crushed/destroyed by improper technique. Instead of scraping, gouging or dicing the tissue, one should be slicing into the stem (gently) with a SHARP, STERILE blade. I prefer a razor, usually in the form of an "exacto" blade -- a tool of the artist's trade that has a nice handle and very sharp, replaceable blades. Slicing does not harm the cambium layer to any great extent and creates an opening that is accessible to the rooting hormone. Which brings me to the next point: use a liquid hormone, not a powder when treating your plant stems. The recommended formulation should contain both indolebutyric acid (IBA) and naphthaleneacetic acid (NAA) in relatively equal amounts. One such product that seems to work well is Dip 'N Grow which can be found in several gardening catalogs. The reason for the use of liquids? The solution immediately goes into the stem tissue, allowing for the best use of the hormone in the place that will actually be able to use it. By their very nature, powders, (for obvious reasons) will not give you the same results. Callusing (necessary before root initiation occurs) will appear to almost burst forth from the area that has been sliced. Strong, thick roots are usually seen within four to ten days after the cuttings have been stuck.
Humidity, Bright Light and Warmth
In order for the cutting to generate the energy needed for root initiation, it must continue to carry on photosynthesis. The few leaves that have been left attached will work to supply the necessary food for this. However, without a root system, they have no method of water uptake -- hence the need for 100% humidity (i.e., plastic bags, mist systems, etc.). Bright, filtered light is also necessary for the production of chlorophyll. However, if the light is too intense the cutting will only be working toward staying alive, not in root regeneration. Too little light limits chlorophyll production, and therefore the energy needed to create the new root system. Possible methods for lighting: bright interior window, grow lights, dappled shade under a tree and greenhouses with a shade cloth, to name but a few. Cold and extreme heat will cause most plants to become dormant. Obviously, a dormant plant is not going to be initiating a great deal of root growth. Stressing a cutting with temperature extremes is a sure-fire way of killing it. Either attempt cuttings when the temperatures are relatively moderate or use a climate-controlled facility (greenhouse or inside the home).
Sterile Soil/Medium
Any medium will work if it is well drained and sterile. Some contain nutrients or can easily hold them, while others are nothing more than a place for roots to grow. Too much water contained in the medium will cause rotting of the cutting; non-sterile soil will decrease the take rate due to the pathogenic elements present and dry soil will be of no use at all The medium should be moist, but not sopping wet or totally dry. Personally, I prefer to saturate and stir my medium (when using a soil-type material) and let it drain awhile before using. Recently, I've started using Oasis trays/cubes for cuttings for ease and space retention.
As you can see, I've given you a few hints on how to provide (for your cuttings) the basic essentials needed for root regeneration. Don't feel that my "technique" is the only way, it is merely the methodology that works for my particular situation. Take what is shown above and develop your own technique. That's what makes being a rosarian so much fun -- being adventurous and trying new things.
