Your garden: How to make liquid manure

Expert advice on what to do for your garden this week.

Vegetable garden
Onion plants can have their tops bent over to assist bulb swelling.

Crops sown in autumn will be almost ready for pulling. If harvested in hot, settled weather, they should be well ripened and suitable for long storage. Thick-stemmed bulbs will probably not keep well, so keep aside for immediate use.

Liquid manure assists most crops.

Make your own by tying a sack filled with sheep, horse, cow or poultry manure and suspending it in water for a few days. One kilogram of fresh manure to five litres of water is a suitable mixture.

Excellent liquid manure can also be made with soot (0.5kg to five litres of water), or seaweed. The latter is good for silverbeet, asparagus and cabbages.

Nitrate of soda and sulphate of ammonia (2 Tbsp to 20 litres of water) promotes leafy growth in salad crops and any winter greens not growing as fast as they should.

Early potatoes can be lifted as foliage yellows. Once potatoes are well matured, a combination of rain and warm soil could prompt new growth, spoiling the crop's quality and storage properties.

Radishes do not keep well in the ground so successive sowings are needed for regular crops.

The plants like a well-drained, free soil with plenty of humus. Keep it moist and prevent the radishes turning tough and stringy, running to seed or tasting too strong.

Sow seed 1cm deep in rows 30cm apart. Water if necessary and thin early.

Brussels sprouts may need to be staked to prevent those in exposed positions twisting in the wind.

Spring cabbages are best when harvested early.

Select a good strain of seed and make one sowing at the end of January and another two weeks later. Choose a sheltered spot in semi shade for the seed bed. Enrich the soil with some sieved compost.

Sow thinly in shallow, 1cm-deep drills and cover firmly. Transplant the seedlings when big enough to handle.

Cabbage aphis and white butterfly caterpillars are ready to attack at this time of the year. Protect seedlings with insecticide spray and/or derris dust.

Celery should have any off-shoots removed from the base before the plants are earthed up. Tie the stalks together to prevent soil entering the hearts.

Draw up about 10cm of soil at first, then, if growth is rapid after a fortnight or so, draw up another 10cm.

Strawberry plants can be cultivated from rooting runners appearing now. Use only the first on any vine and, after it has established roots, set it out in rich soil in early March. A strong plant will then develop to bear a fruit crop next summer.

Strawberries like plenty of compost, leaf mould and maybe some very old manure.

Superphosphate applied when planting will supply the phosphates important to full growth.

Do not use lime, as strawberries prefer a slightly acid soil.

Flower garden
Lilium candidum, the Christmas or Madonna lily, will have finished flowering by the end of this month. Cut the old flower stems off at ground level and destroy to prevent the spread of botrytis.

Lilium candidum has no resting period. Fresh growth develops from the bulbs as soon as the flowering period is over, so if bulbs are to be divided or shifted, the work is best done now.

Lilies like a deep, reasonably rich, well-drained soil. Set the top of the bulb no more than 5cm below the surface.

Multiply bulbs by detaching scales and inserting them upright in boxes of sandy soil with the tip of each scale just below the surface.

Keep the boxes moist, preferably in a cold frame, and plant the scales out when they have rooted. Plants propagated this way may flower in the second season.

Peonies and pyrethrums become dormant after flowering so now is a good time to lift and split them if they have become overcrowded or more plants are required.

Water if the weather is dry and mulch with garden compost to retain moisture.

Shrubs flowering on the previous year's shoots will benefit from pruning now. They include Weigela florida, mock orange (Philadelphus coronarius), rambler roses and Kerria japonica or Japanese rose.

Remove as many flower-bearing shoots as possible, without spoiling the shape of the shrub. In good soil, vigorous growth will be made between now and autumn, forming next spring's flowering shoots.

Violas and pansies may be straggling now and producing smaller flowers. Cut to just a few centimetres above the ground to encourage new shoots.

These will provide cuttings and rooted pieces for replanting in autumn.

Tulips and hyacinths can be lifted and cleaned when they have completed their growth. Lay the bulbs in shallow trays in a dry, cool, airy place. Do not expose them to full sunshine.

Anemones and ranunculi can be lifted and stored for a month or two, until planting space is available.

Many gardeners rely on raising fresh stocks each year from seed saved from the best blooms or bought from a reliable source. For winter blooms, plant some anemone bulbs now in a warm place.

Narcissi, crocuses, snowdrops and many other spring-flowering bulbs may suffer if kept out of the soil for any length of time. Lift only when overcrowding makes this necessary and replant without delay.