Developing strong plants

What to do in the garden this week.


Blackberries need to be pruned after fruiting. Photo: Gillian Vine
Blackberries need to be pruned after fruiting. Photo: Gillian Vine
Cabbage, cauliflower and silverbeet stalks should be cleared from the ground once the plants have been harvested. Left in, they will deplete the soil and, more seriously, shelter insect pests such as grey aphids.

Spinach, lettuce and turnips can still be sown, the latter in a warm, sheltered place. Onions need to be lifted soon. If the foliage is still growing, bend over the tops to hasten bulb maturity.

If onions are already being used, dig those with thick, soft stems first, as they will not keep well. Cabbage, cauliflower and leek crops need to be kept cultivated and weed free.

Control moth and caterpillar attacks with derris dust. A pesticide spray may be needed to combat grey aphid infestations.

Silverbeet grows well in cool conditions and in most areas a mid-March sowing still gives enough time for plants to become established before cold weather stops growth. Sow silverbeet seed 1cm deep in rows 50cm apart. Water the ground well if conditions are dry.

Being coastal in origin, silverbeet also responds to some salt in the soil. Place some seaweed 30cm below where the seeds are to be sown, cover with soil, then put in the seeds. This leafy vegetable also responds to a plentiful supply of organic material.


Lilies can be planted in rich, well-drained, lime-free soil, giving the bulbs a chance to settle down before winter. Lilium regale is popular in home gardens, being easy to grow and less sensitive to soils containing lime.

Most tolerant of lime is the madonna (Lilium candidum). The other main difference is that madonna lilies, which have no dormant period, should be planted in a hot, dry spot with a third of the bulb above the soil.

Other lilies need plenty of leaf mould or peat to maintain the acidity in which they thrive. Most lilies like to have shade over their roots and look good beside azaleas, rhododendrons and kalmias. In heavy soils, drainage can be improved by sitting the bulb on a layer of river sand.

Stem-rooting lilies should be planted 8cm-10cm deep, basal-rooting 15cm or more deep.


Loganberries, boysenberries, tayberries and cultivated blackberries need to be pruned after fruiting. Cut from the base of the plant all canes which have fruited, and train young canes in their place.

If there are not enough of those to replace the fruit-bearing ones, the plant has been starved. Mulch with rotted manure or garden compost at least 50cm out around all sides of the stems.

Raspberry bushes can be cleaned up by tying the canes into place, removing all weeds and any suckers that have appeared. Leave seven or eight newly grown canes to each plant and remove old ones which bore fruit this season.

A mulch of half-rotted manure or compost will help the plants develop strongly for next season's fruiting.

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