How to Grow Silvanberries in Australia

Silvanberry (Rubus 'Silvan') is a trailing blackberry in the rose family, Rosaceae, grown for its large, glossy black berries in early summer. It was bred at Silvan in Victoria by the state agriculture department, with 'Marion' blackberry and boysenberry in its parentage. The mistake many gardeners make is cutting out next summer's canes in winter.

Three mistakes that matter

1. Cutting out the wrong canes. Fruit forms only on canes that grew the summer before, so a hard winter prune of every cane removes the coming crop. Cut out only the canes that have fruited, as Pruning and Training shows.
2. Planting without a trellis. Canes can trail 2 to 7 m, tangle into a thicket and root wherever their tips touch the soil. Put the posts and wires in before planting, and tie canes up as they grow.
3. Dry soil from flowering on. Without steady moisture while the fruit forms, berries stay small and lack flavour. Mulch well and water deeply right through flowering and picking.

When to plant

Plant canes in winter, while they are dormant, leafless and sold bare-root. The cue is dormancy rather than soil warmth, so plant once the soil is workable and not waterlogged. One planting crops for many years, so there is nothing to sow in succession. Like most blackberries, it needs a cool winter to fruit well, which rules out the tropics.

In cool districts, planting can run into September, as long as the cane is still dormant when it goes in.

Site, soil and setup

Choose a permanent position. It is not rotated like a vegie crop, but avoid ground where raspberries or other brambles died of root rot.

Planting Canes

Silvanberry starts from a dormant bare-root cane. Raspberry, blackberry, boysenberry, loganberry, youngberry, tayberry and lawtonberry each have a guide of their own.

Bare-root preparation

A bare-root cane arrives as a leafless stem above a bundle of roots. If planting must wait, heel the cane into a shallow hole in a cool spot and keep it watered, so the roots stay damp. Before planting, soak the roots in a bucket of water for 1 to 2 hours, and no longer, or they may rot. Seaweed solution at 30 mL per 9 L can go into the soaking water. Trim off any broken or dried-out roots.

Where it may be planted

Wild European blackberry (Rubus fruticosus aggregate) is a Weed of National Significance, and each state and territory sets its own rules. Some name 'Silvan' as an exempt cultivar and others name none, so check the row for your state before you plant.

Due to quarantine restrictions and our shipping policy, we cannot send Silvanberry canes to Western Australia or Tasmania. Wherever you garden, keep the canes on the wires and off the ground so the tips do not take root. Netting the fruit also helps, since birds spread the seed.

Planting on the trellis

• Build the trellis first, with a star picket every 4 m between strainer posts at each end. Run three wires: the lower two at 50 cm and 1 m, the top at 2 m.
• Dig a wide hole beside the wire line and spread the roots out in it.
• Set the cane shallow, with its roots about 10 cm deep and the base of the stem level with the soil surface.
• Backfill, firm gently and water in with seaweed solution at 30 mL per 9 L.
• Cut the cane back to about 20 cm to push new growth from the crown.
• Mulch with straw, lucerne or sugarcane mulch, not woodchip.

Care by growth stage

Steady water and a switch from nitrogen to potash as flowers open decide the crop. Months are for temperate gardens and run later in cool districts.

Once berries start to colour, net the trellis with white, wildlife-safe netting stretched taut, with mesh too small to push a finger through. On very hot days, drape shade cloth over the row to save the fruit from sunburn.

Pruning and Training

Each cane lives for two summers. In its first it grows long and leafy, as a primocane (first-year cane). In its second it flowers and fruits as a floricane (fruiting cane), then dies back.

• As new canes grow, tie them along the lowest wire or bundle them loosely, off the ground and away from the fruiting canes.
• Weave or fan last year's canes along the upper wires. They are brittle, so bend them gently.
• In summer, pinch out the tips of very long new canes to encourage side branches.
• After picking, cut every cane that fruited down to the ground.
• Then lift the new canes onto the empty upper wires and tie them in for next summer.
• Remove weak, damaged or crowded canes, and pull out any shoot coming up away from the row.

If the fruited canes are missed after picking, cut them out in winter while the plant is dormant.

Companion planting

Silvanberry needs a row of its own that you can reach from both sides, so keep companions low and at the row ends.

Grows well with

• Alyssum, whose small nectar-rich white flowers draw hoverflies and other predatory insects.
• Calendula, whose open yellow and orange flowers also feed hoverflies.

Keep apart

• Raspberry and other brambles, which share cane spot and Phytophthora root rot (Phytophthora species).
• Vegie beds that are dug often, where rooting cane tips and stray shoots become weeds.

Harvesting Fruit

Berries usually ripen from about mid-December in temperate gardens; pick them when they have turned from red to fully black and feel slightly soft.

• Check and pick every 3 to 4 days once berries colour.
• Take the whole berry: its core comes away inside the fruit, unlike a raspberry.
• Ripe silvanberries hold well on the cane, so a missed day is rarely lost.
• Remove mouldy or damaged fruit as you go.

The soft fruit bruises easily and does not keep well, so chill unwashed berries and use them soon. For longer keeping, freeze them or cook them into jam, where their high pectin helps the jam set.

Eat them fresh from the cane, or use them in pies, sauces and desserts.

Common problems

Little fruit in the first summer. A new plant usually crops best from its second year; see Three mistakes if every cane was cut.

Canes wilting and leaves browning from the edges. In warm weather on wet, heavy soil this points to Phytophthora root rot, which destroys the fine roots so plants pull out easily. Read more

Small, dry or tasteless berries. Water ran short during flowering or fruiting; see Three mistakes.

Scorched leaves and shrivelled fruit. Hot summer sun burns both foliage and berries; give afternoon shade as Care by growth stage describes.

Fruit gone before you pick it. Birds and possums take ripe berries; net the row as Care by growth stage describes. Read more

New plants springing up along the row. Cane tips root where they touch the soil and form new plants, so dig them out and keep every cane tied up.

Pests and diseases

Most bramble diseases start in damp, crowded canes, so open training and clean prunings do much of the work.

Downy mildew (Peronospora species). Pale green to yellow blotches on the upper leaf turn red and purple, with pink to tan patches beneath. Infected green fruit reddens early, then shrivels and hardens, mostly in warm, wet weather. Read more

Grey mould (Botrytis cinerea). Flowers turn brown and grow grey fuzz after several wet, cool days, and the fungus moves on to the fruit. Pick off affected flowers and berries, and keep the canes thinned.

Cane spot (Elsinoe veneta). Small purple spots on young canes enlarge and turn grey in the centre, and leaves show yellow spots that can fall out as holes. Start with clean canes and give them space.

Redberry mite (Acalitus essigi). These tiny, whitish mites, about 0.5 mm long, leave berries that ripen unevenly, with some drupelets hard and red. Wild blackberries nearby harbour them, so remove any wild plants close to the row.

Two-spotted mite (Tetranychus urticae). Leaves turn speckled and bronzed, often with fine webbing underneath, in warm to hot, dry summers. Keep the soil moist, and avoid sprays that kill the predators that keep mites down. Read more

Queensland fruit fly (Bactrocera tryoni). Females lay eggs in maturing and ripe berries, and the maggots make the fruit decay and drop. Bird netting does not keep it out. Where the fly occurs, cover the row once fruit sets with fine insect netting, holes about 2 mm across, secured to the ground. Pick promptly, and freeze fallen or stung fruit in a sealed bag for two days before binning it, never in the compost. Read more

Prevention first

• Start with healthy, disease-free canes.
• Thin and train the canes so air moves through the row and leaves dry quickly.
• Cut out fruited canes each year and take old prunings away from the row.
• Keep weeds down, because light brown apple moth survives winter on weeds such as dock and capeweed.

Tips

1. One plant is enough to start, because silvanberry is self-fertile.
2. While you pick, tie a loop of wool around each fruiting cane, so the right canes come out afterwards.
3. Wear thorn-proof leather gloves for pruning and picking, since silvanberry is one of the thorniest brambles.
4. Bin or bag prunings and never dump them in bushland, where cane pieces can take root.