I added the wrong type of fertiliser (meant for fruiting) into my pots of roses and the plants started to dry up. The tips of the stems, leaves and buds also appear dark and dry. I tried to undo my mistake by diluting the fertilised soil with water but this is not working so well. Also, the leaves have been eaten by some insects or worms. How can I save my roses?

The symptoms suggest an overdose rather than using the wrong type of fertiliser.

The next time this happens, dilute and wash out the excess amount of fertiliser in the soil by leaching with water.

Remove the soil and cut away any injured roots that appear black in colour.

Do the same for damaged leaves as these cannot be revived. It is always wise to follow instructions on the fertiliser label and remember that more is not necessarily better. It is better to use the fertiliser at half strength and twice as often.

As for the leaf damage caused by pests, you can opt to use a systemic insecticide where the chemical is absorbed into the plant's sap. Any chewing insect that feeds on the leaves will consume the insecticide as a result.

Systemic insecticides are not washed away by water or rain like contact insecticides. Always read the directions on the label before applying systemic insecticides as they may not be suitable for application on some plants.

This question, published in The Straits Times on February 23, 2008, were answered by Mr Wilson Wong,
founder of Green Culture Singapore (www.greenculturesg.com), a local website for plant lovers..

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