Propagation from Cuttings
The following method can be used to propagate from cuttings azaleas, small and large leaf rhododendrons, and many other woody shrubs, both broad leaf and conifer.
Wearing gloves that will protect your hands from chemicals, prepare Clorox solution by combining one part Clorox to ten parts water. Also mix up the Captan fungicide at a ratio of one quarter teaspoon Captan to 8 liquid ounces of water.
Determine from a reference book, such as The Reference Manual of Woody Plant Propagation: From Seed to Tissue Culture by Dirr, the time to take the cutting from the plant of interest and the concentration of hormone needed to root the cuttings. Place a small amount of the hormone in a thimble sized container, i.e.,35 mm film canister. Some rooting powders such as Hormex come in different strengths. Hormex has six premixed strengths ranging from 0.1% to 4.5 %. These strengths can also be listed as parts per million (ppm), for instance 0.1% = 1000 ppm and 4.5% = 45000 ppm. What is important here is that the strength of the rooting powder used is in the ball park of that recommended for the cutting material. For most cuttings either 0.3% (3000 ppm) or 0.8% (8000 ppm) strength rooting powder can be used. Do not return remaining used rooting powder to original container when finished.
In an area where you can work and make a mess, prepare the containers that will hold the cuttings by cleaning and rinsing well with a Clorox solution, 1 part Clorox to 10 parts water. Do not rinse the Clorox solution off. The container should be able to be sealed well enough to maintain a high humidity around the cuttings, yet allow light to reach the cuttings. There should be a few small drain holes in the bottom of the container.
In a large clean container, wheel barrel, pan, etc. dry mix equal volumes of peat moss and perlite.
Take your cuttings. Following are some considerations. The plant should be healthy, well watered up to two days prior to taking the cuttings and should have at least an inch or more of new growth that is beyond the tender stage. If the stem to be cut has both tender new growth and mature new growth, the tender new growth can be removed. Take the cuttings as early in the morning as possible, at least before noon. Each cutting should be at least 1" long (not including tender new growth). Late in the growing season some plants will have 8 to 12" or more of suitable new growth on stems. From such stems 2 or 3 cuttings can often be obtained. Place the cuttings in a plastic baggie and mark on the bag the name of the cultivar or species, where obtained and date using a permanent marker. Keep the bags out of the sun. If your away from home have an ice chest handy with ice and a way to keep the cuttings from coming into direct contact with the ice. Most cuttings can be held at normal refrigerator temperatures for a week or two before sticking.
NOTE: When you're desperate to obtain a copy of a particular plant regardless of the above, take the cutting, it may root.
Here are some factors pertaining to taking cuttings to remember. Not all clones of a species root easily. Therefore if you are taking cuttings of species, select cutting material from plants that have a chance of being genetically different to increase the odds of getting a clone with high rooting potential. Above all else, the most significant factor in rooting cuttings is to have cuttings from a clone with high rooting potential. Plants, i.e. cultivars, that are in the nursery trade usually have a high rooting potential. Other important factors having a bearing on rooting are the age of the plant from which the cutting is taken, old plants do not root as readily; and the time of the year which the cutting is taken. This last factor is probably the second most significant factor in the rooting of cuttings. To increase the odds of obtaining cuttings when the rooting potential is the best, determine from references when the optimum cutting time is and then take cuttings every week for two to three weeks on both sides of optimum. Cuttings from vertically growing stems when rooted will tend to grow vertically, while horizontal stem cuttings when rooted will have the best chance of growing in other than a vertical direction.
It is now time to stick the cuttings. Add some water to the dry mixed sphagnum peat moss-perlite mix. Do not wet mix more of the rooting medium than is needed for the current days work. Gauge the proper amount of water by lightly squeezing some of the medium, when opening your hand if the mix holds the squeezed shape and no water came out of the mix when squeezed, it is suitable for use. Fill the rooting container, do not pack the mix into the container. Tapping the container on the work bench top a time or two is enough to get the mix settled and yet maintain some air spaces. Set the container off to the side for now.
Prepare the cuttings by first removing any flower buds, seed pods and tender tip growth. Take all leaves off broad leaved cuttings except the top 4 to 6 and for conifers remove the bottom 1" to 1 -1/2;" of branches and needles. Of the leaves remaining cut off about a third to one half of each leaf. Generally, chose for the remaining leaves those that are not to damaged by insects, fungi, etc. On the bottom 1 to 1-1/2 " of the cutting slice off a small sliver (wound) of the stem. Now get your gloves on. Actually, you should keep the gloves on for all operations once the containers are filled with the rooting medium. All the cuttings that have been prepared are first completely immersed in the Clorox solution for 2 to 3 seconds. Each cutting is immersed individually then laid out on a paper to drain. When all the cuttings have been through the Clorox solution they are then immersed in the Captan solution. Take a cutting , tap it on the paper to remove excess Clorox solution then completely immerse it into the Captan solution for 2 to 3 seconds then lay it out on paper to drain. NOTE: Captan tends to settle out of solution so stir frequently.
Next take a cutting that has been through the solutions, tap it to remove excess solution, and then coat the wounded bottom portion of the stem with the hormone rooting powder. Try to keep solutions from running off the cutting into the hormone powder container because it eventually makes coating the stems difficult. Also, the rooting powder should form the thinnest of layer on the stem. Tap off any excess.
Now place the cuttings in the rooting medium to a depth at least as great as the length of the wound. Cuttings can be placed as close as 1" to 2" apart in all directions. It is possible to get as many as 7 cuttings stuck in a prepared 2 liter soft drink bottle or 5" pot. When all of the cuttings have been placed in the container water around the stem of each cutting to settle the rooting medium around the stem. Minimize getting water on the cutting except at and below the rooting medium level so that the Captan is not washed off the cutting. Next lightly tap the container on the work surface once or twice to insure that the cutting stem is in good contact with the rooting medium. Place the cover on the container. Mark on a piece of tape the contents of the container, the date the cuttings were stuck and any other information to be retained, and place it on the container. Note: for simplicity and convenience, only cuttings from the same clone or species source should be placed in a container. This eliminates the problem of dealing with different rooting times and reduces the possibility of fungus infections spreading.
Now place the container in a north facing window under fluorescent light (cool white bulbs) or just under fluorescent lights. The lights should be within 8" of the top of the container and should be left turned on for 16 hours each day.
On a weekly basis, preferably more often, check the cuttings to make sure there is not a fungus or insect problem. If so spray the cuttings with the Captan solution or appropriate insecticide. Remove any leaves that have fallen or dead cuttings. Also, check the rooting medium occasionally to see if it needs water, most times it does not. The easier cuttings are usually well rooted in 6 weeks, the more difficult a few months.
Frequently after a few weeks, roots may appear above the rooting medium. That is a good sign. Something that is not necessarily a good sign is new stem and/or leaf growth. This does not necessarily indicate that rooting has occurred. Many times when removing rooted cuttings you will find a healthy looking cutting that has not rooted if restuck it may yet root.
Before removing the newly rooted cuttings from the rooting container the new plants must be hardened before transplanting and full exposure to the outside environment. With the 2 liter bottles the lids (caps) are removed and just set on top the bottle for a few days. Then the lid is completely removed for a few days. For containers covered with half mil plastic a few slits can be cut into the plastic followed a few days later by the removal of larger areas of plastic.
Be very careful removing the rooted cuttings as the roots are very tender and break easily. Newly rooted cuttings can be potted up in 4" or larger pots using potting medium composed of 4 parts peat moss, and 4 parts perlite. Water in with a dilute liquid fertilizer, about 1/4 strength and continue using on a weekly basis for a month after which a small amount of fertilizer such as Osmocote 17-6-10 can be top dressed around the pot. Usually after potting, or if a plant begins to look stressed, a 2 liter bottle top without lid is slipped over the pot or is covered with a clean piece of floating row cover for a day or two
The hardening off of newly rooted plants is a very critical process. In the first year or two of propagating, I probably lost more plants because they were not hardened off properly.
Remember this is just one way to root many different types of cuttings. Experiment.
Propagating Supplies:
A. M. Leonard, 241 Fox Drive, P.O. Box 816, Piqua, OH 45356, 1-800-543-8955, www.amleo.com
Forestry Suppliers, Inc.,P.O. Box 8397, Jackson, MS 39284-8397, 1-800-647-5368, www.forestry-suppliers.com