After all the initial aspects have been considered and the root cutting has been made, the next step is to consider the question of what treatment the cutting may need in order to enhance its chances of producing a stem bud and then surviving until the bud develops and establishes as a new plant. At present there are no growth-promoting substances available for root cuttings, so that it is not possible to enhance bud production in this way. The special powders produced for inducing roots on stems should not be used on root cuttings as they will actually depress bud production.
The best way to protect a root cutting is to treat it with a thin powder film of fungicide such as Captan. The root cutting, when planted, will be more or less completely surrounded by soil or compost and as such could easily become waterlogged and so subject to all sorts of fungal rots. The survival of the cutting will very much depend on protecting it against this possibility.
Place the cuttings in a polythene bag, add some fungicidal powder, using about one teaspoonful of Captan for every 100 1 in
Treating root cuttings mi cuttings. "Balloon" the bag by twisting the top and then shake it vigorously. Once the cuttings are coated with a powder film, they are ready for planting.
It will be apparent why it is important to be able to recognize the top and bottom of the cuttings after such processing.
Root cuttings need to be planted in a medium that will support them, prevent them from drying out, allow adequate aeration and, when regeneration starts, provide basic nutrients. All these features can be found in the ground outdoors and the root cuttings will do well there provided that the soil is reasonably light or they are placed under a cold frame in soil to which peat and grit have been added. However, except perhaps for a few very vigorous herbaceous perennials, it is more convenient to plant root cuttings in a container and then plant them out just as soon as they are established.
Select a container of suitable size for the number of root cuttings to be propagated, allowing 1-1^ in for each cutting. For example, plant seven cuttings in a in pot. Fill the
2 Close the bag and shake until all the cuttings are covered with fungicide.
3 Fill a pot with compost. Make a hole with a dibber. Plant cutting vertically.
1 Place the root cuttings in a bag filled with some fungicidal powder.
container with a peat-based compost containing loam, which will act as a buffer to prevent excessive drying and will maintain an even level of nutrients. Strike off the compost with a presser board so that it is level with the rim. Then press the soil down to at least f in below the rim of the container.
Make a hole in the compost with a dibber and then plant the root cutting. Place the top of the cutting just level with the top of the compost. Firm back the compost around the cutting. Space the remaining root cuttings evenly round the container.
Cover the cuttings with grit. Strike off with a presser board until the grit is level with the rim of the container. This weight of grit tends to compress the compost slightly so causing the tops of the cuttings to be pushed further up into the grit. This will provide almost perfect aeration for the bud that will develop at the top of the root cutting. Do not water. Label the container and stand it in an environment (propagator, cold frame, etc.) that is appropriate to the size of the root cutting (see page 39).
Some plants, for example Romneya coulteri, do not like being dug up and having their
Planting root cuttings
roots disturbed. Therefore, place only one or two of their root cuttings in a small pot and treat as one plant, disturbing their roots as little as possible when transplanting them once they are established.
Keep watering to a minimum to maintain a well-aerated compost, which encourages bud development and reduces the likelihood of rotting. In fact there is probably no need to water at all if the root cuttings were initially planted in a reasonably moist compost and a humid environment is maintained.
Very often when the bud first develops, it produces a stem and green leaves but no root system. This will grow later from the base of the new stem. Even if the new roots do develop from the cutting, they too will not appear until after the stem and green leaves have grown. Do not water until the roots appear as the cutting is still liable to rot.
Place in a well-lit area once the stem appears. Harden off any young plants propagated in a warm (21°C/70°F) environment before planting out or potting up. Apply a liquid feed, according to the manufacturer's instructions.
4 Plant remaining root cuttings in apart. Cover the pot with grit.
5 Strike off the grit until level with rim. Label, and leave cuttings to develop.
6 Do not water until the roots have appeared. Then apply a liquid feed.
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