How to Grow Youngberries in Australia

Youngberry (Rubus hybrid, often sold as Rubus ursinus) is a trailing cane berry in the rose family, Rosaceae, grown for its shiny black-purple fruit. It was bred in Louisiana from a dewberry and a blackberry and raspberry cross, and it ripens in early summer, a little ahead of boysenberry. The soft berries bruise too easily to travel, so growing them is the way to taste them. The mistake to avoid is pruning off next summer's crop.

Three mistakes that matter

1. Cutting out the new canes. Youngberry fruits on canes that grew the summer before, so a winter tidy-up that removes the green new growth removes next summer's berries. Cut out only the canes that have fruited, as Pruning and Training explains.
2. Planting without a trellis. Trailing canes left on the ground tangle, take root wherever their tips touch the soil and are hard to pick. Build the post-and-wire trellis before planting, so you never disturb the roots to put it in.
3. Letting the soil dry out in summer. Without a steady daily supply of moisture from flowering to the last picking, berries stay small and lack flavour. Water deeply at soil level and keep a thick straw mulch over the roots.

When to plant

Plant bare-root canes in winter while they are dormant: June to August in most districts, and into early spring in cold ones. Youngberry needs a cool winter to flower and fruit well, so it suits the south best and struggles in the tropics. One planting crops for many years, so there is nothing to plant in succession.

Plant canes as soon as they arrive.

Site, soil and setup

Choose a bed that will not be dug, since the plant stays for many years. Do not plant where tomato, potato, eggplant, capsicum or strawberry grew in recent years. All of them host Verticillium wilt (Verticillium dahliae), a soil-borne fungus (see Pests and diseases).

Building the trellis

• Set a strainer post at each end of the row, with posts or steel star pickets every 3 to 4 m between.
• Build it about 2 m high, with three wires.
• Run the two lower wires at about 50 cm and 1 m to hold the new canes.
• Run the top wire at about 1.8 to 2 m for the canes that will fruit.
• Along a boundary fence, fix the wires to outriggers (short arms) so the canes sit clear of the palings.

Planting Canes

Youngberry starts from a bare-root cane: a year-old plant cut back to a single stem and lifted without soil. Due to quarantine restrictions and our shipping policy, we cannot send youngberry canes to Western Australia or Tasmania. Raspberry, blackberry, boysenberry, loganberry, tayberry, silvanberry and lawtonberry each have their own guide.

Bare-root preparation

A healthy dormant cane has firm, fibrous roots and a strong stem. Take the cane out of its bag and shake off the packing, and do not let the roots dry out. Soak the roots in a bucket of water for 1 to 2 hours, no longer, or they can rot. Seaweed solution at 30 mL per 9 L can go in the soaking water.

Planting on the trellis

• Dig a hole about 30 cm deep beneath the wires and build a small mound in the centre.
• Sit the cane on the mound and spread its roots evenly down the sides.
• Backfill so the roots sit about 10 cm down and the base of the stem finishes level with the surface.
• Firm the soil and water in with seaweed solution at 30 mL per 9 L.
• Cut the cane back to about 20 cm to push strong new canes from the base.
• Spread straw mulch around the plant, keeping it clear of the stem.

Care by growth stage

Steady water from spring to the last picking, potash more than nitrogen, and canes tied up off the ground decide the crop. An established plant repeats these stages every year. The months suit most southern gardens, and the zone table shows how harvest shifts by zone.

Once the first berries colour, cover the trellis with white, wildlife-safe netting pulled taut, with mesh too small to push a finger through.

Pruning and Training

Each cane lives two summers. In the first it grows long and leafy (a primocane); in the second it fruits on short side shoots (a floricane), and never again.

• Tie new canes loosely to the lower wires as they grow, in a bundle or a fan.
• Keep every cane tip off the soil.
• After the last picking, cut each cane that fruited at ground level.
• Untie the new canes, lift them to the top wire and tie them there for next summer.
• Keep about ten strong canes per plant, and cut out weak, damaged or crowded ones.
• Dig out suckers that come up away from the row, or pot them up as new plants.

The canes are sharply thorny, so wear thick leather gloves and long sleeves to prune and pick. To tell the canes apart, tie each year's new growth to the opposite side from the last. In very fertile soil, pinch out the tips of over-long new canes in summer.

Companion planting

A youngberry row fills its trellis, so keep companions low and at the ends of the row.

Grows well with

• Alyssum, a low insectary plant that draws hoverflies, lacewings and tiny parasitic wasps without shading the canes.
• Calendula, whose flowers bring bees to the row.
• Thyme, a low edging whose flowers feed bees and hoverflies.

Keep apart

• Tomato, eggplant and capsicum, which host Verticillium wilt.
• Strawberry and potato, which carry the same wilt in the soil.
• Raspberries and wild blackberries, which share cane pests and diseases, and whose suckers tangle with youngberry.

Harvesting Fruit

Pick berries once they turn fully black-purple and glossy and feel slightly soft, usually from November to January, often in time for Christmas.

• Check the canes every 3 to 4 days while fruit ripens.
• Pull each berry gently; the core comes away inside the fruit.
• Remove mouldy or damaged berries as you go.

Youngberries are best eaten soon after picking, and they keep only for a short time in a covered container in the fridge. For longer keeping, freeze them or cook them into jam, which sets well thanks to the fruit's natural pectin.

Eat them fresh, or turn them into sauces, pies, crumbles and hot or cold desserts.

Common problems

No fruit on a new plant. Fruit comes on second-year canes, so a new plant crops fully from its second summer. If an older plant stops fruiting, see Three mistakes.

Few flowers or fruit in warm districts. Mild winters give too little chill for the canes to flower well, so choose a cooler, winter-shaded site.

Small, crumbly berries. Each tiny segment of a berry swells only after pollination, so few bees leave gaps, and dry soil leaves small fruit.

Scorched leaves and fruit. Hot summer sun burns both, especially on north and west sides, so give afternoon shade or drape shade cloth on hot days.

Canes spreading through the garden. Suckers rise from the shallow roots and stray tips take root; Pruning and Training shows how to keep both in check.

Fruit and shoots eaten. Blackbirds and other birds take ripe fruit, and possums eat both fruit and young shoots; net the trellis as Care by growth stage describes. Read more

Pests and diseases

Most youngberry troubles in Australian gardens start with stress: wet roots, dry heat or crowded, damp canes.

Two-spotted mite (Tetranychus urticae). These tiny mites feed under the leaves, which turn speckled yellow-white, then bronzed, often with fine webbing. They build up in hot, dry summers and after sprays that kill their predators. Read more

Grey mould (Botrytis cinerea). Flowers turn brown, then furry grey, in humid weather, and developing berries can be infected too. It strikes when weather stays cool and wet for several days, so remove affected fruit and avoid heavy nitrogen in spring.

Queensland fruit fly (Bactrocera tryoni). Females lay eggs in ripening berries across northern and eastern Australia, and larvae rot the fruit from inside. Bird netting lets the flies through. Where they are active, cover the trellis after flowering with fine insect mesh, sealed to the ground and clear of the fruit. Pick promptly. Before binning stung or fallen fruit, freeze it or seal it in a bag in the sun for at least 14 days. Keep it out of the compost. Traps show when flies arrive but will not control them alone. Read more

Downy mildew (Peronospora species). In warm, humid, wet weather green berries redden early, then shrivel and harden, and the disease survives winter inside the canes and crowns. Thin and tie canes early so the canopy dries quickly.

Phytophthora root rot (Phytophthora species). In warm, wet soil the fine roots die, new canes wilt and tips die back, and plants lift easily from the ground. It thrives where water ponds, so plant on a mound in heavy soil and never overwater.

Verticillium wilt (Verticillium dahliae). Leaves and canes yellow, wilt and die back because the fungus blocks water flow from the roots. There is no cure, so remove affected plants and plant new canes in fresh ground. Read more

Prevention first

• Start with healthy, disease-free canes, and never replant suckers from a sick plant.
• Water the soil, not the plant, pick off leaves with brown spots, and keep canes tied up and thinned so air moves through.
• Check leaf undersides, flowers and ripening fruit regularly, and more often as the weather warms.
• Avoid broad-spectrum sprays; pyrethrum harms bees, so if you must spray, do it late in the day away from open flowers and follow the label.

Tips

1. Tie a length of wool around each cane as it fruits, so pruning time holds no guesswork.
2. Plant a boysenberry nearby to follow on, since youngberries usually ripen about two weeks earlier.
3. For a spare plant, push a cane tip into a pot of potting mix while still attached, then cut it free once rooted. See layering.
4. Thornless youngberries are easier on the hands, though they tend to crop less than thorny plants.