'Stopping' the Shoots to obtain Bushy Plants

When pot plants are raised from seeds, 'cuttings' or by other methods, they require a certain amount of attention to ensure that 'bushy' compact plants are obtained.

To induce plants to form basal shoots, the tips of the main shoots are pinched out to stop them from growing straight upwards without 'breaking' (Fig. n). The effect of the removal of the tips is to cause the side shoots to develop.

This 'pinching' is done just above the fourth or fifth leaf, in order that the new shoots may form as near as possible to the base of the stems. With many species of plants, one 'stopping' is sufficient, but some plants need this treatment a second time. This second 'stopping' is done when the new side shoots have made 2 or 3 inches of growth; the tips of these secondary shoots are pinched out just above the fourth or fifth leaf (Fig. 12).

Plants which are grown for their ornamental foliage can be stopped at any time of the year when they are growing freely. Generally, however, it is done in spring and summer when the plants are in active growth.

Fig. 12. A geranium (Pelargoniumzonale) has been cut back and is forming side shoots

Plants which are grown for their flowers, however, should not be stopped within 2-3 months of flowering time.

Ferns, palms, Selaginella, and all plants which form rosettes of leaves close to the tops of the pots may be allowed to develop naturally, and require no 'stopping' or 'pinching'.

Repotting and Top-dressing

These operations should be done in spring when new growth is beginning. Some plants, such as Clivia, Aspi­distra, Ceropegia and Hoya can remain in the same pots for several years, and their vigour can be prolonged by top-dressing with good potting soil each year. Other quick-growing types, such as Fuchsia, Solarium and Pilea, must be repotted annually.

For the majority of plants, a mixture of 6 parts of loam (or garden soil of medium texture), 2 parts of leaf-mould or granu­lated peat, and a 1/4part of silver sand is quite satisfactory. The John Innes Potting Compost No. 1 is suitable for most plants. It can be purchased ready mixed or the ingredients can be purchased from nurserymen.

Formula of John Innes Compost No. 1

Medium loam 7 parts }To each bushel of compost add Granulated Peat 3 parts } 4 ozs. of John Innes Base fertiliser Silver Sand 2 parts         }   and ¼ oz. of carbonate of lime.

John Innes Base fertiliser can be obtained from any nurseryman or seed shop.

Method of Repotting

Invert the plant and tap the rim of the pot sharply on the edge of the table or potting bench. Then examine the ball of soil. If it is tightly packed with roots, repotting is needed. Select a clean pot of a size larger than the one the plant has been occupying and make provision for drainage. Pieces of old flower pots are best for the purpose. Select one piece -which is slightly larger than the drainage hole and place it with the hollow side downwards over this hole. Then place inthree or four pieces about half the size of the first crock and spread a few smaller pieces over them. Finally, put a thin layer of rough siftings from the compost material over the top layer of crocks to prevent the compost from being washed in among the crocks.

At the base of the ball of roots the old crocks will be found. Remove them with a pointed stick and disentangle some of the roots which are not too tightly entwined.

Fig. 13. Potting arum lily Firming the compost with a potting stick

Next, spread a thin layer of compost over the rough siftings and make it firm with a blunt potting stick (Fig. 13). Then set the plant in position, taking care not to cramp the roots under the ball of soil and add the compost, a little at a time, making it firm as it is being added. Leave a space of about \ inch at the top of the ball for watering.

Plants which are not Pot-bound

These will be best left as they are for a period or until the roots have spread well around the outside of the ball of soil, before repotting is done. In some cases it will be found that the soil has become sour or it has worked down into the drainage crocks; it is then best to repot the plants into fresh compost, but to use the same-sized pots.

Fig. 14. Cyclamen persicum (latifolium)

Giving a light sprinkling of fertilizer

Treatment after Repotting

The root disturbance, due to the repotting, will prevent the plants from obtaining sufficient moisture from the compost until the roots pene­trate the fresh material. But, at the same time, moisture will be given off by the leaves and unless this loss of moisture   (transpiration) is checked, the  plants will be slow in recover­ing. Consequently, precautions must be taken to reduce this loss of moisture by keeping the foliage damp by spraying or sponging the leaves frequently with clean water. Select a semi-shady position for the plants, where they should remain for 3-4 weeks before being set in sunny positions.

Other John Innes Potting Composts

The J. I. (John Innes) Compost No. 1 mentioned on page 22 is the standard compost and is suitable for most plants which are grown in pots up to the 5 in. size. J. I. 2, which has two doses of the base fertiliser and lime, can be used for potting plants into 6 or 7 in. pots andj. I. 3, having 3 doses of base fertiliser and lime, is suitable for setting plants into 8 in. pots or larger.

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