Green plant in a white pot.

How to Control Your Plants

Insects and diseases can be controlled using chemi­cals, and physiological problems will need changes to the environment, but with a virus, control is impossible, and it can be spread from plant to plant by such sap-sucking insects as aphids. The only answer is to get rid of the plant and start again.


Chemicals are available in several different forms, from liquids to powders, and more recently, pins. The way they work differs in that some rely on direct contact being made between chemical and pest (called “contact” insecticides), while others are absorbed by the plant’s roots and are distributed around the plant in its sap (called “systemic” insec­ticides).

Contact chemicals are slightly less effec­tive in a large infestation, as insects underneath leaves may be untouched. Systemic chemicals are effective because they circulate within the plant’s whole system, so any insect feeding on the sap of any part of the plant takes up the chemical, too, and is killed. Neither damage the plant in any way.

Dusting can, either be applied as a spray (mixed with water according to the instructions) or as a dust (the active chemical is mixed with talc for easier distribution). The dust pack should be used outdoors on a windless day.

Inserting a Plant Pin

Pins are cardboard strips impregnated with systemic chemicals, which are released into the soil for about a month before disintegrating. Place at the edge of the pot (to avoid root scorch) and push down firm­ly into the soil mix.


As an alternative to using chemicals, many pests can be dislodged by spraying with, or inverting the plant into, a bucket of soapy water. Make sure the plant is thor­oughly immersed for 2—3 minutes (not the soil), then allow to drain.

Painting the Pest

Pests with a waxy outer coating, such as scale insects, can he painted with rubbing alcohol first, to break down the wax so that the contact chemical is more readily absorbed. Use a fine paintbrush or cotton swab for accuracy.

Steps to a healthy plant

  • Make sure the plant is watered regularly
  • Apply plant food when required
  • Position the plant so that it receives enough light
  • Provide an environment in which the temperature is consistent
  • Do not allow the atmosphere to become too dry or too humid
  • Leave the plant alone during periods of dormancy
  • Keep the plant away from drafts
  • Repot when necessary so that the plant’s growth is not restricted
  • Check soil is sterile and not infected by worms or other pests
  • Make sure that leaves are free of dust
  • Group plants together to create a microclimate