Your garden: Preparing for autumn frosts

What to do in your garden this week...

• Vegetables
By now, cooler areas may well have had a touch of frost but in all regions carrots, being cold-tolerant, can be left in the ground until August.

Lettuce can be sown from now until early April in gardens with suitable conditions for growing them over the winter. Select hardy types and grow them under cloches or in large pots on a sunny porch. Autumn-sown lettuces need well-drained soil, rich in compost.

Onions can be sown now to stand over the winter and autumn sowing is best in the South for the likes of Pukekohe Long Keeper. Select an open, sunny place, adding well-rotted compost. Onions do well in well-limed soils, so add dolomite lime to areas where onions are to be grown.

Runner beans will produce until frosted. Covering them at night will help delay the inevitable and if basil and other tender herbs and vegetables are grown nearby, a large frost cloth can cover the entire area and prolong harvesting.

Regular watering or liquid manure applications will ensure the maximum bean crop, as will picking them as soon as they are ready to eat. Small is definitely beautiful in this case and avoids the unpleasant stringiness that puts many people off these nutritious vegetables.

• Flowers
This is the month to plant bulbs for spring displays. Making excellent companions for daffodils are old-fashioned, sweet-scented red-brown wallflowers planted beside a late-flowering variety of daffodil.

Purple violas also look good with late-flowering daffodils.

Southern gardeners have it over their northern counterparts when it comes to tulips for these hardy bulbs prefer winters that chill them thoroughly and they are intolerant of humid conditions.

They like a sunny spot and can be left for years, although lifting them when the foliage dies down is recommended. Careful selection of varieties will give tulip flowers over a longer period.

Crocus corms and Iris reticulata are seen better if planted along the edges of paths, while glory of the snow (Chionodoxa luciliae), snowdrops (Galanthus) and bluebells (Hyacinthoides) are good for rose beds or used to cover bare ground under trees.

Rambling roses will have completed their flowering season and can now be pruned. If there is plenty of new growth at ground level, cut off old branches that have borne flowers.

If new growth is scanty, simply remove worn or diseased wood and cut back faded flower trusses and seed hips. A liberal dressing of compost or commercial rose fertiliser will encourage fresh growth next season.

Lawn grass seed will still germinate in most areas if sown this month or next.

• Fruit
Tomatoes grown outdoors may need covering at night as a precaution against frost. Reduce watering to encourage the crop to ripen before hard frosts kill the plants or ruin unripened fruit.

Remove any leaves shading the fruit clusters and pinch out the vigorous side shoots which can appear at this season.

Glasshouse tomatoes should be given the same treatment to keep them fruiting as long as possible.