Boysenberry: cultivation, care & taste

Boysenberries are an increasingly rare bramble hybrid. Although they are not sold in supermarkets, they are easy to grow at home. Why not give it a go!

A cross between four different Rubus species, the aromatic boysenberry has the growth and fruit colour of the blackberry, and the shape of the loganberry. Here is a guide to this unusual hybrid, as well as some tips on how to grow boysenberries at home.

Boysenberry: origin, flowering time, and characteristics

The boysenberry (Rubus ursinus x idaeus) is said to have originated in California in the 1920s. The shrub is a cross between the loganberry (Rubus x loganobaccus), European raspberry (Rubus idaeus), European blackberry (Rubus fruticosus) and American dewberry (Rubus arboriginum). Named after its creator, Rudolf Boysen, it was marketed from the mid-1930s as a blackberry alternative in the USA and later, in New Zealand. Today, New Zealand is the world’s largest producer and exporter of boysenberries, but in Europe, this Rubus species has remained largely unknown.

Boysenberry is an upright or overhanging shrub that reaches a height of between 100 and 180cm. The plant’s roots form rhizomes, which create new plants along the ground. Its serrated leaves cluster in groups of three, and are bright green until autumn. There are both thorny and thornless varieties of boysenberry, but generally, they are moderately thorny.

This bramble begins to flower in late Spring, and continues to display its white, five-petalled flowers until August. Insects like the bumblebee (Bombus) and honey bee (Apis) pollinate boysenberry, as it offers nectar and pollen, and its 3cm long, elongated to cylindrical fruits ripen from mid-July to September, turning red to dark purple and black. The berries taste sweet and slightly tangy; rich and fresh.

Planting boysenberries: timing, location and method

Boysenberries prefer sun to semi-shade, and fresh, humus-rich, deep soil. Initially, the plants can be placed in pots with a minimum volume of 15 litres and a well-draining, nutrient-rich potting mix such as our Plantura Organic Tomato & Vegetable Compost.

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Whether it is in a pot or garden bed, the bramble must be supported and provided with a climbing aid such as a trellis or fence. Boysenberries can also be trained to grow over arches. The optimal time to plant boysenberries is in late autumn between October and the end of November, or in March. Keep a distance of at least 100 to 120 cm between plants.

Before planting boysenberries, enrich the soil with organic matter such as mature compost or an organic soil improver. Then, loosen the soil well using a fork and dig a hole. The hole should be at least twice the size of the plant’s root ball. Place your boysenberry in the hole, fill it with soil, and lightly press. Finally, water the bramble thoroughly.

How to care for boysenberries

Taking care of boysenberries is not particularly complex; the brambles are generally robust and adaptable. Once boysenberry plants are well established, you only need to water them during long dry periods. If space is limited, reduce the numerous long canes to 8 to 12 and train them up a trellis or wire frame. This also makes harvesting easier and prevents the fruit from resting on the ground.

How to prune boysenberries

Boysenberry canes only fruit once. As such, prune dead floricanes close to the ground in autumn, when the shrub becomes dormant, and all but 5 to 7 primocanes. This will ensure that your boysenberry directs its energy towards fruit and cane production next year.

Fertilising boysenberries

It is a good idea to fertilise boysenberries in spring. Work mature compost or a slow-release fertiliser, such as our Plantura All Purpose Plant Food, into the surface soil around the bushes.

For potted boysenberries, move your plant to a larger pot with fresh potting soil after two to three years and add an additional dose of slow-release fertiliser to the fresh soil.

How to overwinter boysenberries

Boysenberries are hardy to about -12°C. However, it is a good idea to protect them from severe sub-zero temperatures in frost-prone and cooler areas. Cover the base of the plant with foliage or straw, and the canes with hessian fabric or coniferous branches. This insulation will significantly reduce the risk of frost damage.

For potted boysenberries, it is best to shelter the plant from the frost or protect their root system with straw and hessian cloth.

Harvest and how to use boysenberries

Between mid-July and September, you can harvest the fruit of high-yielding boysenberry bushes. Once the fruit changes from red to a dark purple or black, the berries are ripe, and their aroma fully developed. It is best to pick the berries by hand and eat them the same day. They can be stored in the refrigerator for a few days, but will lose their rich flavour.

Because boysenberries do not keep well, it is best to make them into delicious jams, pies or tarts. The berries are also great in cake toppings, fruit wine, syrup, and liqueur. They can also be frozen and enjoyed at a later date. The biggest problem is not eating all the berries straight away when you pick them in summer!

Another particularly aromatic cross between blackberry and raspberry is the tayberry (Rubus fruticosus x idaeus). Read our tayberry growing guide to find out more about this hybrid.