Boysenberry Rubus ursinus x idaeus

Boysenberries are big, fat, delicious fruits that look like a cross between a raspberry and a blackberry – which in fact they are. They aren’t really a berry at all but they still taste good in spite of this mis-identification. Boysenberry plants behave just like blackberries and produce arching stems that can be as long as a car. In our gardens we generally restrain them by training them against a wall or fence or growing them into a tree or over a shed like a climbing rose. The berries are delicious raw or made into jam, high in antioxidants they are a ‘must’ if you have room for a plant or two.

Companions Marigolds to draw predatory insects like ladybugs and hoverflies

Quantity 1 plant per household – more if you have room.



Boysenberries

  • Plants grow into large thorny bushes
  • May need support of trellis or frame
  • Varieties for all parts of country
  • Rich, acidic soil
  • Fat, juicy, delicious berries


Varieties

There are over a hundred varieties of apple available in New Zealand. The best way to work out what suits you is to order catalogues from growers in late summer and match available varieties with your tastes, growing conditions and climate. Many apple trees are what’s called ‘self fertile’ meaning they can be grown on their own but some need another tree to help with pollination – this information is normally included on labels or in plant descriptions in catalogues. Take a look at some of the old-fashioned heirloom and heritage varieties that are returning in popularity, you’ll find some great apples not only rich in flavour but rich in history too.

Apples are divided into several categories and these may help you on your quest for what’s best:

Crab apple: old-fashioned varieties with small, bitter fruit that are most often made into jams, jellies and sauces. Often planted with other apple trees as a pollinator. ‘Floribunda’ is often planted for its delicate pink blossom and ‘Golden Hornet’ for its decorative profusion of red and yellow fruits.

Dessert apple: the common eating apple with sweet tasting juicy fruits – some of which are also good for cooking. Divides into three groups –
Early – Fruits start to ripen in early summer. Good varieties – ‘Oratia Beauty’, ‘Winesap’, ‘Devonshire Quarendon’.
Mid – Fruits ripen from late summer into autumn. Good varieties – ‘Freyburg’, ‘Golden Delicious’, ‘Egremont Russet’.
Late – Fruits ripen from mid autumn and are produced through winter. Good varieties – ‘Granny Smith’, ‘Braeburn’

Cooking apple: large fruits with thick skins and a tart bitter taste. Usually cooked and preserved. Trees often grow into large, spreading shapes and fruit ripens mid-to late season. Good varieties – ‘Bramley’s Seedling’, ‘Mayflower’ and ‘Sturmer’.

Getting started

When

The best time to plant boysenberries is from autumn into winter when plants are dormant.

Where

Plant boysenberries in full sun. Good for growing countrywide, they can handle winter frosts down to -5 degrees centigrade. They are often trained against trellis or fences.

Soil

Boysenberries like a rich, free draining soil with lots of organic material in it. Soil should be slightly acidic – so look for lots of organic material as an indicator. If your soil is sandy or slightly sticky then you’ll need to add peat and well-rotted compost at the time of planting and continue to mulch with rich compost as your plants get established. You can always grow a boysenberry plant in a container or raised bed filled with peat and well-rotted organic compost if you have a sticky clay soil.

SOW & PLANT

PLANT

Plants should be spaced two strides apart. Soak plants in water before planting them.
Prepare the planting area. Soil should be weed-free and well dug through to at least a full spade’s depth. Add well-rotted compost and peat if necessary and mix with surrounding garden soil. Carefully remove boysenberry plant from container by turning it upside down and holding the plant across the base of its stem with a spread hand. Tap the bottom of the container until the plant and its root ball come loose. If it is in a plastic plant bag simply slit it down the side whilst the plant is standing in the planting hole, you can then slip the plastic bag from underneath. Handle plants by the root ball to prevent damage to stems and shallow roots. Place boysenberry plant in a hole that is just larger than the container it came in. Back fill around root ball making sure there are no air pockets. Water well and mulch with a finger-thick layer of peat, pine needles, shredded bark or untreated sawdust.
If planting in a container ensure it is large enough. Half barrels look good with boysenberries and they are the right size too. Use a rich compost with peat in it and plenty of organic material. Add slow release granules or sheep pellets before planting. When boysenberries are grown in containers they should be constantly monitored to ensure soil is moist – particularly in dry weather.  Plants are often placed against a wall with trellis on it to which they can be attached or with a metal training pyramid or cylinder standing above the pot.

MAINTAIN

Keep plants weed free and maintain constant moisture levels – this is especially important during spring and summer when plants are growing and crucial once plants have formed fruit. Always water at the base of plants – avoid splashing foliage as this can spread fungal disease.

Feed: Depending on how well you have composted the ground you might want to give your developing plants an extra boost with some liquid seaweed or worm juice every 6 weeks. If you maintain a nutrient rich layer of mulch around their base this should give them all they need in the first few years as they become established.

Flowering: Boysenberries flower in spring, they are self-pollinated but bees will help to increase yields.

Care: Tie stems to training wires or trellis as they grow. Keep plants open and ensure good airflow – especially in warmer areas where humidity can result in fungal diseases like mildew.

HARVEST OR PICK

Fruit are formed in spring and early summer when they start to ripen. Harvest does not last that long - normally between 4 and 6 weeks. Regular picking keeps fruit ripening. Fruits are ready when they turn from red to a deep, rich purple. They should come away from the stems easily when they are fully ripe. Taste is, of course, the ultimate test of readiness – boysenberries have a rich, sweet, rounded flavour. Don’t wash fruit as this causes them to deteriorate quickly. A mature plant can yield up to 4kg of fruit in a season.
Storage: Boysenberries keep in the fridge for up to a week as long as they are not piled high in a bowl. To freeze, pop freshly-picked, unwashed berries onto a plate or tray in the freezer. When they are frozen add them to a bag. Repeat this process over a period of time until you have frozen and stored all you want. When they are defrosted they will collapse due to excess moisture and are best used in puddings and jams where they are cooked.

PRUNING

In winter cut back all the canes that have produced fruit to ground level and remove any others that are damaged or spindly and weak. Fresh young canes left on the plant will grow to produce the next season’s crop, pinching out their tips encourages growth of fruit bearing side shoots.

PESTS

Boysenberries can suffer from a range of pests and disease - some of which are easier to deal with than others. Green vegetable bugs, caterpillars and passion vine hoppers can be tricky customers to regulate in larger plants. Aphids, thrips and scale insects can be treated with Neem oil spray. If grown in the right soil and the right location and kept weed-free plants should be less susceptible to diseases such as mildew. Birds are an issue as soon as fruit start to ripen so protect your plants with mesh.