One cause can sometimes be reasonably difficult to locate and identify.

A close inspection may reveal small fluffy white blobs, about the size of a match head, underneath the leaves or flowers or around the base of the plant.

This will indicate the presence of mealy bug. If the plant is badly infected it is probably preferable to dispose of the plant in a plastic bag and then place it into the garbage.

However, if the plant is not too badly affected, and the owner is willing to spend the time, the white blobs can be removed by using a cotton bud that has been dipped into methylated spirits and then dabbing the solution on to the pests.

Frequent inspection of susceptible plants should be undertaken as the pests can spread to other plants, particularly if they are growing in close proximity to each other.

May is a good time of the year to plant some of the more unusual types of vegetables.

An economical way to grow asparagus is by seed, or with seedlings. If asparagus is grown from seed then the plants should be left to grow for about two or three years for a strong root system to develop. The stems should not be picked during this time, with the plant being allowed to grow naturally.

Another way to grow asparagus is by using the asparagus crown, with long, fleshy roots. The crown of the Asparagus is where the spears will grow.

To plant the crown, dig a trench and then make a little mound in the bottom of the trench. Sit the roots of the crown over the top of the mound. Place the plants about 40cm apart. If the roots are damaged cut them back because they are quite fleshy and grow again easily.

Asparagus is very hungry and needs plenty of organic matter such as animal manures. Scatter it thickly along the bottom of the trench at planting time.

An asparagus plant can also be placed into a single hole or a couple of asparagus crowns can be grown in a big pot. Water well, once planted, so the air pockets get away from the roots. Then in spring, little shoots will appear.

In order to assist the plant to develop into a healthy plant with a strong root system, it is preferable to avoid harvesting the stems in their first year. Blood and bone is an ideal fertiliser to use with asparagus culture.

Rhubarb can be grown in a wide range of soil types, providing they are well drained, but it prefers deep loams well supplied with organic matter.

Rhubarb is usually propagated by planting pieces or divisions of 'crowns' formed during preceding seasons.Under ideal conditions, a strong, healthy division will produce a sturdy plant in one season's growth and some stems may be harvested in this first season.

Crown divisions are usually planted about 90cm apart and covered with 5 to 7.5 cm of soil and firmly pressed into place.Large amounts of organic matter (animal manures) should be used.

Choose a sunny or lightly shaded spot and dig plenty of organic matter into the planting area. Some pellets of Dynamic Lifter can also be mixed into the soil before planting. As soon as the leaves appear, begin applying organic mulch around the plant (without directly touching the stems) and water regularly with a liquid plant food such as Thrive or Aquasol. Sydney Crimson is a reliable rhubarb variety that performs well in a wide range of climates.

When harvesting rhubarb, pick the largest stalks from the outside of the clump. Pull the stalk cleanly downwards and sideways. Always leave at least four stems in the centre of the clump.

Rhubarb leaves are poisonous and should never be eaten. However, the leaves can be used to make a rhubarb spray for insect control. Boil rhubarb leaves with water, using approximately three leaves per 500ml of water - and add a small amount of soap (ordinary flaked bath soap) to the mix.

Globe artichokes prefer to be grown in sandy soil, although any kind of soil is suitable. They should be fertilised with sheep manure and potash. The potash makes them flower and bud up better, producing the part that is harvested.

Globe artichoke plants should be available for harvest in twelve months.

Pots of Zygocactus plants that were placed into areas where they only received natural light once they had finished flowering last year they should now be coming into full bud. Some earlier varieties may even have commenced flowering.

Zygocactus and certain other plants such as chrysanthemums and poinsettias set their flower buds when the hours of darkness reach a certain level.

Pots of Zygocactus can be enjoyed indoors if they are placed in a well lit position while they flower. They make most attractive subjects for hanging baskets as their naturally pendulous flowers are most attractive when viewed from below.

In order to enjoy the same display next year it is important to again place the pots into an area of natural light, where they will only receive light during daylight hours, once they have finished their flowering cycle.

- Perennials and autumn flowering shrubs, including lavender bushes, should be cut back as the flowers begin to die off.

- Winter vegetables such as silverbeet, lettuce, cabbage, broccoli, peas and beans can be planted out now, adding a handful of dolomite per square metre of garden bed.

- Now is an ideal time in which to transplant or plant out evergreen trees and shrubs, while the soil is still warm