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Horticulture 1000
H1092 - Plant propogation 2 - Asexual propagation
Encouraging root growth

Asexual propagation

You may have seen a plant in a friend's garden that you have admired and would like to grow yourself. You could buy the plant at a garden centre or you could propagate it yourself. Propagation is when you produce new plants.

If you use seeds (sexual propagation) to propagate the plant, there is a chance the plants will not be exactly the same as the parent plant. The offspring will not breed true.

To make sure your plant will have the same flowers and growth habit you could take a piece of the plant. Taking a piece of a parent plant to make a new plant is called asexual propagation. Asexual propagation includes methods such as taking leaf, root or stem cuttings as well as dividing plants into pieces.

Hebe plants can be successfully propagated from a piece of stem Hebe plants can be successfully propagated from a piece of stem.

The new plant will be exactly like its parent. Identical plants like this are called clones. Many plants for sale at a garden centre will be grown by asexual propagation except for annual flowers and vegetable seedlings.

Methods of propagation are continually changing and being developed. An example is tissue culture, a very specialised propagation method. Cells are separated from the parent plant and grown on a nutrient rich media in sterile, warm, humid, environmental conditions. Thousands of plants can be produced from a small portion of parent plant tissue.

Here are advantages and disadvantages of asexual propagation.

Advantages of asexual propagationDisadvantages of asexual propagation
  • The new plants are exactly the same as the parent plant.
  • Many plants can be grown from one parent plant.
  • The new plant will grow faster and flower at an earlier age than those grown from seed.
  • There is a risk of transferring disease from the parent plant to the new plant.
  • Cutting material is often bulky and perishable.
  • Some of the propagation methods are difficult, time consuming and more expensive than growing from seeds.

Tools used for asexual propagation

Asexual propagation usually involves cutting off a part of the parent plant.

There are special tools for this:

Tools used for asexual propagation
  • secateurs: the main cutting tool suitable for making cuttings from all plant material
  • scissors: useful for making cuttings of soft or thin stems. Also useful for removing leaves from cuttings
  • knives: a general purpose knife for dividing plants and cutting tubers into pieces
  • a grafting and budding knife for budding, grafting and fine cutting work.

Care of your tools

  • Keep them sharp and oiled. This will make the job of cutting easier.
  • Keep them clean and dry. A dirty or wet tool can transfer diseases to the cut plant.
  • Use them correctly and avoid cutting material beyond the tool's ability. Tools will be ruined if the stem is too thick or hard. Cuts may end up ragged and so provide a better entry for disease organisms.

Complete Activity 1A in your workbook

Key points   Key points

  • Asexual propagation results in plants identical to the parent plant.
  • This is a fast method to produce plants and is commonly used by nursery people requiring a line of identical plants.
  • Some methods are difficult, requiring specialised skill and knowledge of the plant's growth.
  • Tools should be kept clean and sharp and stored safely in a dry place.

What's next?

Go to: 2 Encouraging root growth.

Encouraging root growth