All are attractive and all need full sun and a well-drained and not-too-rich soil that has a neutral or slightly alkaline pH.

Sweet william is an annual or biennial growing to two thirds of a metre with flower clusters in multi-colours.

They bloom heavily in November and December and often longer.

They often self-sow, but fresh seed should be used each year if you want to be sure of having new plants coming on.

Garden pinks are the most cold-hardy perennial forms of dianthus.

They don’t like very hot summers. The clove-scented flowers can be single, double or fringed.

These low-growing mats are good choices for the front of the sunny, well-drained border or in the rock garden on dry slopes.

Don’t mulch them, even in winter, because they rot easily.

They can be propagated from seed or cuttings.

A hybrid between the carnation and the cottage pink, dianthus allwoodii, retains the dwarf characteristics of the pink and has, under good conditions, the all-summer blooming period of the carnation.

It grows to 30 centimetres and has sweet-scented, mostly double flowers.

Members of the dianthus family like soil that is a little alkaline, so are excellent temporary plants to grow close to a new house (because of the builder’s lime) until the remainder of the garden is formed.

Sometimes you come across plants that are not doing well even though the gardener has dug in blood and bone or artificial fertiliser.

Of course soil needs a lot more than this if plants are to thrive.

Like us, plants need air, water and food.

If soil is fine or compacted, air can’t get into it, neither can adequate water,     and so nutrients that are there don’t become available to plants.

The sort of soil in which air and water can enter easily  and be retained without draining quickly away is crumbly, with lots of organic matter. It has good tilth, as they say.

You can see impoverishment taking place on agricultural land  that has had nothing but superphosphate added to it for many years.

There are various ways we can increase the organic matter in our soil.

One is mulching regularly with such things as grass clippings, hay, straw, weeds that haven’t gone to seed, seaweed, leaves and so on.

This mulch will gradually break down into valuable humus and can be worked into the soil after vegetable crops are finished.

Growing cover crops, or green manure crops and digging these in when they have reached a lush growth, will vastly increase the organic content of the soil and make it healthier.

Conifers, in their many colours, can enhance the garden all the year round, but they are a trap too.

Many a gardener has planted a little beauty, only to find many years later that it is becoming a monster which will be very difficult to remove.

You can avoid this, if you want to fill only small spaces, by ensuring that you buy only dwarf varieties, and there are hundreds of these.

Abies, of firs, for instance, have several lovely dwarf forms, and they do well in Tasmania.

Several of the cedars are excellent dwarfs.

Diselma archeri is a native of Tasmania. It grows to about a metre high and has an attractive weeping habit.

Microcachrys tetragona is a Tasmanian alpine which makes an attractive prostrate plant about a metre high.

If you want a dense, narrow column of grey green colour about 45cm high try juniperus communis compressa.

Remember that most conifers are slow-growing.