Plant Propagation: Creating Many Plants from One

We are all familiar with growing plants from seeds, but there are many other ways to propagate plants.   Asexual propagation is accomplished by means of cuttings, layering, division and grafting.  Some of our favorite fruit trees have been cloned, or asexually propagated, for many years, so that each new tree is identical to the original parent.  The original Delicious apple tree dates to 1870 and the Bartlett pear to 1770 – older than the United States.

Seeds

Plants have been managing without us for millions of years, in the process developing some unique adaptations.  The Chaparral of southern California, like many plants in fire-prone environments, has seeds that need to be burned in a fire before they will germinate.  Many plants require the assistance of animals to spread their seeds.  Burrs become attached to an animal’s fur (or our clothes) and are thus taken to a new location.  Other seeds are inside fruit or berries that are eaten by animals and birds, pass through the digestive tract and ultimately begin to grow in a new spot.

Fortunately, commercial seeds come with directions on the packet.  Some seeds germinate quickly, like large bean seeds, while others are more challenging.  Some plants, such as orchids, are generally only grown from seeds by hobbyists, as the dust-like orchid seeds are difficult to handle and grow.

Collecting Seeds

Many experienced gardeners collect and save for replanting the seeds of a choice variety, such as a special heirloom tomato.  The seeds of modern hybrids will not grow true to the plant that they were taken from, but seed can be successfully saved and planted from older varieties.  After all, throughout most of human history, seeds had to be saved for the next year’s crop or there wouldn’t be a next year’s crop.

Asexual Propagation

Cuttings

Cuttings are exactly what it sounds like – a piece cut from the parent plant.  Many woody and herbaceous plants are grown from cuttings, such as the poinsettias seen everywhere at Christmas.  African violets are usually grown from a leaf cutting, rather than from seed.

It’s important to use a sharp knife, sterilized in rubbing alcohol or a bleach-water mix (1 part bleach to 9 parts water).  This prevents the transmission of disease from plant to plant.  Flowers and flower buds are removed from the cutting so that the plant’s energy is spent on developing roots rather than flowers.  Rooting hormones are available in any garden shop and make the process quicker and more reliable.  It’s a good idea to put some of the rooting hormone in a little dish to dip the cuttings into rather than risk contamination of the whole container.

The cuttings are inserted into a sterile rooting medium that is well-drained but still retains some moisture and is low in fertility.  Keep medium evenly moist; eventually, the cuttings will develop roots and new leaves.  Good rooting mediums are soil, water, vermiculite and peat mixed with perlite.  Place the trays with the cuttings in bright but indirect light.  Root cuttings can be started in the dark.

Cuttings can be taken from the stem, the tip of the stem or at a node.  For example, an ivy stem could be used to make several cuttings, with 2 nodes per cutting.  If information cannot be found as to what works best for a particular plant, experiment.  Leaves do not generally make good cuttings, with a few exceptions (African violets).  Root cuttings can be taken from 2-3 year old plants while they are dormant.

Layering

Layering has a higher success rate than cuttings because the new plant remains attached to the parent until it is well-rooted and can be detached.  Mint plants naturally do this by rooting at different places on the stem as it lies on the ground.  For layering, the stem from the parent plant is anchored to the medium.  The side of the stem facing the ground can be scratched and dipped in rooting hormone.  Keep moist until well-rooted.

Runners

Spider plants, for example, grow little plants at the end of a long stem.  The small plants can be rooted and planted.

Offsets

Bromeliads and some cacti grow new shoots at the base or leaf axil.  These can be broken or cut off and planted in a medium until rooted.

Bulbs and Corms

For best blooming, clumps of bulbs (tulip, narcissus) should be dug up, separated and replanted.  Gladiolus grows from corms.  At the end of the season, they can be dug up and the new, little corms surrounding the big corm can be gently broken off, dusted with a fungicide and saved in a cool spot for next year.

Division

Some plants, including iris and day lilies, need to be divided every few years.  The roots can be pulled apart or, if strongly connected, cut apart with a sharp knife.  Old clumps usually bloom better after being divided.  It’s nice to share or trade with friends!

Grafting

Grafting joins parts from two plants so that they grow as one.  Usually, this joins a strong root stock to a top with superior fruit or flowers.  A fruit tree could be grafted with 2-3 different varieties on the same root stock.  A novelty sold from time to time has potato roots and a tomato top, possible because they both belong to the same plant family.  Roses are often grafted to a stronger root stock.  (When planting roses, instructions usually say to be sure to keep grafting point above the soil level.  If this is not done, the root stock may throw up shoots which will develop into a vigorous, not really desirable wild rose.  Personal experience…).

There are many grafting methods, depending on the plant being grafted.  Master gardeners seem to accomplish it easily while the rest of us may have many more failures than successes.  Either seek advice from a pro or read about how to best graft the plant you are interested in and give it a try.

Some plant propagation is easy, such as rooting house plant cuttings.  Other methods, especially grafting, are usually reserved for experts.  However, every expert was once a beginner, so don’t be afraid to try.  Whatever method you use, it’s fun to grow several plants from one!

We know that many Earth Clinic readers love organic gardening. Keep reading below to see what our readers have shared. Please share your experiences and let us know how you propagate your plants!

Sources:

http://pubs.ext.vt.edu/426/426-002/426-002.html

https://ag.arizona.edu/pubs/garden/mg/propagation/grafting.html

http://www.mastergardenproducts.com/gardenerscorner/new_page_4.htm