Understanding how propagation takes place is very important in ensuring no variety of plant is lost and every good gardener should know the art of propagation as not all plants can be propagated in the same manner.  

 

 

Seeds

 

Seeds are formed when the ovules of flowers are fertilized by the pollen found on the stamens of the same flower or carried by insects from another flower. When the ripened ovules are developed into seeds they will contain within it, an underdeveloped embryo – the plant. While it is dormant it is protected by the seed covering. Seed coverings differ from plant to plant. Some are hard shelled, soft skins, husks, etc. These coats protect the cotyledons or the seed leaves. The seed contains enough food which it has stored up to start the life of the new seedling. This is sufficient to carry it through until the roots and the next set of true leaves are formed. The processes by which plants are reproduced by seeds are termed sexual reproduction. 

 

 

Asexual reproduction is achieved when plants are propagated by a process of division such as plant cuttings, root cuttings, etc. 

The conditions most favourable for seeds to germinate or sprout into plants depend on some essential factors such as viable seeds, the all important moisture to soften and crack open the seeds, favourable temperature and air.  Moisture is also important to release the enzymes contained in the seed that convert the starches within the seed into sugars essential for developing the plant cells and tissue which in turn increases the embryo’s growth until the seed can no longer contain it and bursts through to anchor itself in the soil with roots.

 

The plant’s growth is on its way now with new leaves being formed to feed the plant through the process called photosynthesis. Sunlight is an essential factor for photosynthesis to take place. It is what helps to give plants their colour. The leaves absorb nutrients from the air and transfer it through the sap in the cambium layers to the roots. The leaves also function in collecting moisture from the atmosphere and by allowing it to drip to the soil where the roots absorb it to continue the process of converting the nutrients to be freely taken up by the plant. The canopy corresponds to the extent of roots in the soil. Moisture also provides a turgid structure to the plant and is the medium by which nutrients are transferred from the root, which is why plants wilt when it is starved of water.  

 

 

Layering

 

One sure method of propagation is air layering. In this method of propagation the roots for the new plant is forced to start on the stem of the parent. 

By selecting the part to be severed and completely stripping off about ½ inch of the outer bark all around the stem with a sharp knife without damage to the inner wood, stops sap being carried from root to leaf and leaf to root, halting nutrients reaching the entire plant. Once this portion of the bark is removed a small amount of soft soil is bound around the stripped area, with more soil placed towards the top part and secured in place with polythene wrap. This amount of soil will hold the new roots the plant will put out to compensate for the loss of root and continuity of growth. Therefore make sure there is enough soil in proportion to the size of the plant. 

 

 

Roots will have formed within 21 days while still on the parent plant. When there are adequate roots formed, severe the new plant from the parent plant from under the rooted section and plant it in the selected location. At this stage it is best to provide shade or a polythene tent over the new plant for about a month or less depending on the dryness of the air. This will provide enough moisture and reduce leaf loss.    

 

Alternately air layering can be accomplished by bruising the area required to be severed and placing a very small pebble within a small cut to make it stay open. Cover the area with moist soil and secure with burlap or cloth bandaged around the soil. Keep moist until roots have penetrated the covering. Cut from under the rooted area and plant as a new plant. 

It is good to note that by the time roots have appeared in the air layering, the parent plant too would have thrown new shoots under the rooted area to compensate for loss of foliage. This is another sign to indicate it is time to separate the new plant from the parent. 

 

 

Another simple method of layering is done by bending the selected branch and covering it with soil. The branch is secured to the ground by a pin or a peg specially made in the shape of a hair pin or a heavy stone is placed over it to stop it from springing back. These are left in place until it is rooted. Make sure that the entire branch is not covered and that the growing tip is exposed. Once rooted the new plant is cut off from the parent plant and moved to a new location. To encourage quick root formation, the branches are slightly bruised, or scraped, twisted or slightly cut on the underside where the roots are required to be formed. This is done prior to pegging or anchoring in the soil. 

Yet another form of simple layering is compound layering called serpentine layering. Flexible stems are bent in up and down curves and anchored in the ground and covered with soil in multiple down sections. When new shoots begin to appear, rooting too would have started. This usually takes around 21 days to a month when it will be ready to separate.  The new plants can then be transplanted in their new positions.   

 

Continuous layering is achieved by burying a whole branch, taken off plants that are known to readily produce roots and making sure the growing tips are left exposed. After the roots have formed cut the branch between the rooted shoots and transplant in their required positions as new plants. 

Mound layering also known as hillock or stool layering is done by cutting bushes back to a few inches off the level of the ground and heaping loose soil over the cut stumps. Shoots will begin to appear which would have developed roots in the earth mounds. A few months later when the new growth is sturdy enough, these shoots are then broken apart and replanted in the new permanent positions. 

 

(Text by Sylvia Page)