We have just got rid of the old daffodil foliage and it's time to think about planting bulbs. Not the colourful harbingers of spring-like tulips and hyacinths, but some of the interesting and less known bulbs of autumn.

Colchicums are one of the most popular autumn flowering bulbs. Some gardeners confuse these with autumn crocus, for they have the appearance of a giant crocus when in flower. Others call them naked ladies because they produce their handsome lilac, purple or white blossoms in advance of their bulky glossy green foliage.

There are many kinds to choose from, the majority of them flowering during September and early October. The lilac flowered Colchicum speciosum is the most widely offered, together with its white form album and the fully double lilac variety 'Waterlily'.

The true autumn crocus are characterised by the meadow saffron, a small flowered species with delicate rosy-purple flowers.

Crocus speciosus is very similar and has given rise to some superb varieties, amongst them the blue 'Oxonian', pale violet-blue 'Pollux' and lavender 'Cassiope'. All flower from September through to November.

Sternbergia is very similar to autumn crocus. This is becoming increasingly popular, with its bright yellow, waxy, crocus-like flowers during September and October.

Apart from being a successful garden plant, it is most useful for growing in pots for decoration in an unheated greenhouse.

All the crocus type bulbs or corms should be planted immediately after purchase, but colchicums can be persuaded to flower without planting.

Being large bulbs with a sizeable food reserve, it is common practice to stand them on the window ledge without soil or water and let them blossom. Providing the bulbs are planted once the flowers fade, they will not come to any harm.

The hardy nerine is a rather exotic looking bulbous plant that would seem incongruous growing outside. Despite its exotic appearance it is perfectly hardy and produces its pink flowers freely when planted in a situation to its liking.

A south or west facing aspect is preferably the base of a wall being ideal. It likes a good baking from the sun, yet at the same time will not flourish in very dry impoverished soil. Not all autumn flowering bulbs are planted at this time of the year. Cape lilies or crinums are more usually established in the spring.

That is not to say that they cannot be planted now, for both the pink flowered Crinum powelli and its white variety album are available from garden centres growing in containers. Provide a sunny free draining position at the base of a wall. Conversely there is one early summer flowering bulb which should perhaps surprisingly be planted during the next few weeks. This is the Madonna lily, a popular inhabitant of cottage gardens which must certainly be planted before the middle of August in order to produce its over-wintering rosette of foliage.

It prefers a deep soil rich in organic matter and a situation in dappled shade. Given these conditions it will produce its startling white blossoms during early summer the following year.

WHAT'S NEW

Ben Thirran is a late fruiting blackcurrant variety.

Violetta is an early blue fruited plum with a rich sweet flavour.

Tiny Pal is a pure white F1 hybrid tulip for August sowing.

Q How can I kill an ivy which is growing up a wall?

A Cut through the stems at the base. The top will then die and can be pulled off the wall. Treat the cut root stump with a product like Root Out to kill it off completely.

Q The leaves on my carrots are going purple and the roots have been eaten. What is the cause?

A Carrot fly. There is nothing you can do now, but the use of a seed dressing and soil insecticide next season gives good control.