This topic is so vast and techniques are so plant specific, it will be impossible to even cover the tip of the iceberg on this page. However, we hope to provide you with some useful information to introduce you to the many ways that you as a home gardener can reproduce plants for yourself and also become better aware of the many techniques that are used in the nursery trade to propagate plants for your use and enjoyment. A lot of extra reading on this subject is necessary to fully understand all the complexities and aspects of plant propagation. We will only cover some simple methods that practices that the amateur can use, just as we do in every year to enhance our landscape and plant collection. Please feel free to contact us is you have further questions on this topic and we will try to help you further.
Sexual Propagation: This term refers to reproduction of new plants from viable seed or spores produced by the plants natural reproductive system. This method is used mostly for annual and perennial plants which don't require long growth periods, plants that cannot be reproduced by other means, or for plants that are reproduced through hybridization. This page will not cover sexual propagation.
Asexual Propagation: This term refers to the reproduction of new plants from means other than seed. These methods produce genetically identical plants or clones. Methods of asexual propagation include the following:
Commonly Used Methods: (Can by done by the amateur gardener)
Stem Cuttings (Hardwood, semi-hardwood, or herbaceous) Leaf Cuttings vein, petiole, or leaf section) Division (bulbs, corms, tubers, roots and stems, rhizomes, pseudo bulbs, etc.) Layering (air and ground) Root Cuttings Leaf Bud Cuttings Cane Sections
Specialized Methods (used mostly in commercial nursery trade):
PROPAGATING NEW PLANTS
Important considerations in successfully propagating new plants include the media, rooting hormones, misting or continuous moisture, light and temperature. All these factors determine success or failure in asexual plant propagation.
By far, the most common and amateur friendly methods of plant propagation are tip/stem cuttings and simple division. These techniques apply to the vast majority of plants grown for landscaping or personal enjoyment. I will discuss the basics of these techniques.
Propagation by cuttings:
Stem tip cuttings:
Cut a terminal section from an un-branched stem of approximately 6 inch length just below the leaf axil. (length varies with plant size). Remove the lower 2/3rds of the leaves and any flower buds Dip the base in a rooting hormone such as Roottone or Hormodin placing the lower 1/3rd of the cutting into a rooting medium (coarse sand, perlite, or a very porous peat and sand mixture) Keep the cuttings moist at all times via a sprinkling system or enclosed to maintain a constant moisture level. Periodic aeration is necessary as well. Keep cutting out of direct sunlight or any condition that would produce stress. If under misting system, more light can be tolerated. Check cuttings periodically and carefully to determine extent of rooting . Remove cuttings only when fibrous feeder roots are evident Pot cuttings in a loose but organic potting soil and continue to stimulate root development with a root stimulating fertilizer until pot bound. Keep well watered and reduce stress during this period (e.g. place in shaded area)
Please note that the steps above are representative and generic in nature. The type of plant, the length of time needed to root, the strength of the hormone needed, and the proper time of year to take cuttings are very plant specific. As a general rule, herbaceous plants root quickly and easily whereas woody plants take much longer and require stronger levels of rooting hormone. The time of year is much more critical for propagating woody plants. Refer to reference books or talk with people who have had experience with propagating certain plants for more specific advice. Plants are best rooted in either herbaceous, semi-hardwood, or hardwood conditions depending on the specific plant.
TIP: HOW TO SET UP A SIMPLE, INEXPENSIVE PROPAGATION SYSTEM FOR ROOTING CUTTINGS
Get a large opaque/clear plastic storage container with lid, drill 1/2" holes in the lid and bottom of the container for air circulation and drainage. Place 6" of coarse sterile sand in it Keep the sand moist, but not drenched. I prefer to use a talc based powder such as Hormodin, Roottone, etc, For semi-hard wood cuttings, a .3% strength of active ingredient is necessary (e.g Hormodin #2). For hard to root cuttings, use a .8% (e,g, Hormodin #3). Packets of rooting hormone found in most garden centers are only .1% used for soft stem or herbaceous cuttings and house plants. You can also set up a timed sprinkler system "in a greenhouse" using a timer connected to a hose bib - available at most hardware stores, but this restricts you to only summer propagation. Simple dish pans with holes in the bottom filled with coarse sand with periodic misting can be used for cuttings (dipped in rooting hormone) as shown below.
Plant Division: This technique is simple and used most frequently with mounding, clumping, or suckering plants such as most perennials, ornamental grasses, and many tropicals. A hardwood, plant can be divided this way if multi-trunk and each trunk has produced it's own roots. All that is involved is a slice with a sharp knife through the base to divide the plant into smaller bases each with it's own set of established roots. Suckering and stoloniferous plants produce new plants from underground roots and offshoots at the base. These new plants can be easily divided by severing them from the mother plant and reestablishing them on their own. A root promoting fertilizer always helps the re-establishment process.
Grafting: Many cultivars of plants can only be reproduced by grafting methods but this requires proper timing, expertise that comes from practicing the various techniques, and the right tools and plant stocks to graft to. If you want a challenge, give grafting a try but consult a good reference book or a person experienced with grafting the particular type of plant you have in mind. The scion or severed tip section of the desired plant must be of the same genera as the rootstock which it will be grafted to. It is better to use the same species if possible in the case of cultivars.
Why Propagate Plants at Home from Cuttings?
Saves money, especially for seasonal perennials or tender accent plants (e.g. over winter one parent plant and propagate many more from it next growing season) Examples are Impatiens, Begonias, Acalypha, any tropical or tender herbaceous plants
Personal challenge and satisfaction of starting a new plant from scratch.
Self insurance policy - to have a backup plant for a rare selection or plant that would be difficult to replace.
Save space for over wintering - keep only a small rooted cutting rather than a large plant for next year.
Have extra plants of unusual varieties for trading with others.
Plant Sales - a good way to make some extra money to support the purchase of new plants to try.
It's the only way to get a desired plant when not available from local commercial sources.
Plant cultivars can only be reproduced identically by this method.
AFTERCARE FOR ROOTED CUTTINGS
The photo on the right shows cuttings that have sufficient roots to be potted. However, additional aftercare is required. Once potted in a loose, well draining but water retentive soil, the new plant requires additional time to grow additional roots prior to new vegetative growth - known as a "hardening off" period. The size pot should be large enough to allow for additional root growth and the newly potted plant placed in a semi-shady, non-stressful area. A little root stimulator fertilizer will help in this initial root development.
Once the plant is rootbound or the roots have thickened to a mature size, the plant is ready for transplanting to a permanent location, either in a larger container (upsizing) or in the ground. As with most newly or transplanted plants, water well until it is reestablished in it's new home location.and plant at the proper time of the year.
RECOMMENDED RESOURCES FOR MORE INFORMATION
The best academic book on Plant Propagation is written by Hudson, Hartman, and Kester entitled "Plant Propagation - Principles and Practices", published by Prentice Hall, Inc, Englewood Cliffs, NJ, 662 pages. It is a text book which covers all aspects of this fascinating subject.
For Central Texas Native Plant propagation, refer to "How to Grow Native Plants of Texas and the Southwest" by Jill Nokes, University of Texas Press