Friday, September 9, 2011

Propagating from Cuttings

     To me, one of the most amazing things about plants is propagating from cuttings.  It's an amazing process to see take place.  And it's also a very productive and fast means to increase or replace plant stock.  While the process is easier and quicker with some species over others, taking cuttings is not all that hard to learn.  When I first got into horticulture my success rates with cuttings were low because I was learning by trial and error.  I hope to make cutting propagation a little easier for you with this article.
     Cutting propagation yields genetically identical offspring, or clones.  So it's great for when you want more of a specific plant for characteristics it displays.  There could be a number of characteristics.  Maybe the plant was a heavy producer, or was extremely hardy compared to others.  It could be that the plant just looked better than the others.  Whatever the reason for wanting more of the plant, seed propagation would not be the best choice for producing more of the plant.  There is too much genetic variation in sexual reproduction to ensure that you'll get seeds that produce more plants with the same characteristics of the parent plant.  The disadvantage of this lack of genetic variation is that all clones will be susceptible to the same pathogens and pests.  The introduction of the wrong disease can wipe out a crop quickly.  Dutch elm disease is a great example of this principle.  Seed propagation is, however, still a great choice for plant production.
     The cells in plant leaves and stems are differentiating during growth.  This means they are becoming specialized in one function or another.  They are able to dedifferentiate under the right circumstances, returning to meristematic conditions.  In the meristematic condition cells are able to contribute to the production of new roots.  Once cells have returned to a meristematic state they can differentiate into immature roots, or root primordia.  Then the new roots will emerge through the outer tissue of the stem and continue to grow.
     There are many rooting compounds available on the market.  The primary chemical at work in these compounds is the hormone auxin.  Auxin will promote the growth of roots without hindering bud development in most plants; but some, like begonia, will have shoot development retarded by the introduction of auxin to the area of root development.  In these cases the use of auxin is not recommended.
     So, how do you take cuttings?
     The first step is to select a suitable growth tip.  Newer growth is preferred as it will more readily root.  A good rule is to use stems from 4-6 inches long.
A growth tip with at least 4 nodes should be selected

     Once you select a section of stem cut it just above a node so that you have the right length of stem to work with.  Cutting just above a node leaves no unused stem on the plant to die off and cause trouble.  You will now have a length of stem similar to the picture below.
Stem with 4 developed nodes
     You should have your propagation media or cloner ready at this point.  It is important that once you make the final cut to the stem the cutting is put in the media or cloner immediately.  Otherwise air can get into the stem, blocking water from entering, which will kill the cutting.  Now you will cut the leaves and sideshoots from the bottom node or two (one node for media, two for a cloner).
Leaf and sideshoot being removed

     Now you will make the final cut.  This cut should be perpendicular to the stem and just below the bottom node.
Cutting the stem just below the bottom node

     If you are taking multiple cuttings, you can place the prepared cutting in a cup of water for several minutes before placing it in its final destination.  The cutting can also be dipped in a rooting compound at this point.  Now you have a cutting that looks similar to the picture below.
Prepared cutting ready for media or cloner
      Now it's time to place the cutting in a medium for root development.  Potting soil, coco coir, and perlite are a few options.  The medium must be kept moist, but not damp.  It is important that the cuttings don't dry out.  Keep the cuttings under indirect sunlight or artificial light.  Covering the cuttings somehow to increase humidity is beneficial, as is occasionally spraying the leaves with a mist of water.  This helps keep the cuttings going until roots develop for water uptake.  Another method is to use a cloner, like the one pictured below.

     In several weeks you should have new plants with roots that have developed enough to transplant.  If you rooted your cuttings in a medium such as soil or coco and want to transplant to an aquaponic system there will be a couple of extra steps.  First, the cutting has to be carefully removed from the medium.  You can break away most of the medium and rinse off what is left easily.  Then the cutting has to be placed in rockwool or a net pot for raft and nft systems or simply planted into a media bed.
     If you have any questions please email me at brendon.c.tripp@gmail.com.  I'm more than happy to fill in any blanks.


    
  

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