Sew onions now to withstand the winter

Vegetables
Onion seed sown this month will withstand the winter, then mature into good-sized bulbs for harvesting next summer.

Prepare soil with wood ash if you can get it, lime and some garden compost, or a general garden fertiliser. Space cleared of early potatoes or peas is ideal for growing onions. Pukekohe Longkeeper, developed by Pukekohe's commercial growers in 1923, remains popular with home gardeners. Cabbage (Earliball, Green Acre or mini-variety Space Saver), silverbeet and spinach (Winter Queen, Santana) can be sown for use in early winter through to spring.

Late summer and early autumn sowing is important, as they will grow rapidly in good soil before the first frosts slow them down. Sowing seed after a shower of rain is ideal. Make sure beds do not dry out. Weeds gallop through their life cycle at this time of year and seedlings will produce seeds in a few weeks. Dig weed plants - but not docks or dandelions - into the soil, or pull them out and add to the compost heap before the seeds ripen.

Second-crop potatoes, such as Maris Anchor, may be lifted now. Leave the ground vacant, or sow a green manure crop, such as lupins or mustard. Green manuring involves growing suitable plants for about six months and then digging them in before they flower. Where a faster turnover is needed, mustard can be sown, as it will mature in three months. For general purposes, oats and blue lupins are recommended. Lupins add nitrogen to the soil, while oats help break up heavy soils. Field peas and red clover can also be used.

Flowers
Oriental poppies, Aubrieta, Shasta daisies, lupins, delphiniums, pyrethrums, leopard's bane (Doronicum) and other early-flowering herbaceous plants should be trimmed now. Doing it immediately after flowering will encourage some plants, particularly delphiniums, to flower again in a few weeks. Roses, dahlias and sweet peas can also be encouraged to flower longer by regularly removing faded blooms. Summer chrysanthemums should be selectively disbudded to provide good-sized blooms. Leave only one flower a stem on varieties grown for exhibition.

Dahlias benefit from liquid manure as well as conventional watering. Horse, cow, sheep or poultry manure - a third of a 10-litre bucket of manure topped up with water - is fermented for two or three weeks, then diluted to the colour of pale tea and watered on to the ground around the plants. Green material can also be used. Comfrey makes the best green mix, as it is high in nitrogen and potash, but any green weeds and lawn clippings can be used. This is also a good way to destroy convolvulus, docks, dandelions and other perennial weeds that do not rot readily in the compost bin.

Fruit
Strawberries may still be layered, choosing the first new plant on each runner and cutting off the rest. Placing compost around the runners will help roots develop quickly. Transfer new plants to their permanent places in about three weeks. Dig out and dispose of all strawberry plants that have borne fruit for two or more years. Because they can carry disease and take a long time to decay, do not put strawberry plants in the compost bin. For younger strawberry plants, trim off old leaves, clear away weeds and give them a mulch of garden compost mixed with blood and bone and superphosphate.

That prepares them for another active growth period in autumn. Cut out old raspberry stems (canes) that have fruited. Stake or wire young canes, removing any weak, spindly or misshapen ones. Six to nine canes a plant is a reasonable number to supply next summer's crop. A mulch of straw, grass clippings or compost helps retain soil moisture and provides humus. Apply on ground already well saturated by rain or artificial watering. Because they fruit next year on growth made this season, blackcurrants can have all old wood removed once fruiting has finished.

Prunings can be used to propagate new plants. As an alternative to growing in garden beds, currants (black, red and white) can be grown on a fence or trellis. They make useful shelter hedges. Tomatoes grown in a glasshouse or tunnel house should have any yellow or dead leaves removed. Pinch out laterals (young shoots at leaf joints) of bush (determinate) types, ensure all tomato plants have plenty of ventilation and reduce watering as fruits stop swelling and begin to ripen.