Blackberry

Over the last month or so, I’ve watched my small collection of thorny and not so thorny berries come into leaf and start flowering. Barely a month out from Christmas, I’m always surprised at how fast fruit develops from the blowsy white flowers - hard green knobbles transform into ruby-hued, juicy berries in no time. Most of us probably have memories of scrambling down roadside banks, clambering around, and getting scratched to bits harvesting wild blackberries. I spent an hour or so picking a bunch from a particularly fruitful patch one afternoon as a teenager, filling in time down at the harbor while waiting for my Dad to finish work. The bagful of fruit was taken home and unceremoniously dumped in the kitchen sink for a quick rinse. I scarpered when a zillion wee grubs emerged from the fruit, leaving my Mum to deal with the aftermath. 

Blackberries are now available in domesticated, thornless variants (hurrah) and I’ve recently developed a soft spot for the New Zealand-bred, large-fruited Karaka blackberry, often called Karaka berries but not to be confused with Aotearoa’s native but highly toxic orange karaka (Corynocarpus laevigatus) fruit. Many of our most popular berries are blackberry-raspberry hybrids - boysenberries are the most conspicuous of these and a longstanding Kiwi favorite. I’ve also always had a soft spot for the less well-known, but outstandingly-flavoured tayberry, bred in Scotland and named for the River Tay. I once led a colleague on a wild goose chase around the backroads of South Canterbury when I spied a sign advertising this elusive fruit for sale on the roadside when out doing fieldwork. I think she’s forgiven me almost 20 years later; the berries we ended up buying were mighty tasty! 

Bramble berries: a short family history

Bramble berries belong to the genus Rubus, which sits in the Rosaceae (rose) family. The genus is most likely North American in origin and dispersed to Asia, Oceania, Europe, and South America during the Miocene period, five to 23 million years ago. Rubus boasts impressive diversity within its ranks. Hybridization is common, as are other interesting genetic feats such as apomixis (asexual development of seeds without fertilization), so this group of plants presents some interesting challenges for taxonomists. This genetic diversity does result in lots of fun for plant breeders, however, and the upside is we have a fantastic diversity of fruit to eat – something for everyone.

Some key Rubus characteristics include a shrubby growth form composed of long, arching shoots that become woody over the growing season and in most cases, are covered in some sort of prickles, bristles, or hairs. No great surprise that roses – the flowers – are not-too-distant relatives. New shoots grow each spring from a rootstock clump that forms in the soil. Rubus plants can be deciduous or evergreen, most of our common cultivated varieties lose their leaves in winter, but some blackberries native to Europe hang onto theirs. Rubus flowers are often hermaphroditic (male and female parts present within the same flower) and go on to produce aggregate fruits, which we call berries, which actually aren’t berries in the strict botanical sense. They are collections of lots of little individual fruits called drupelets – each flower’s receptacle consists of up to around 80 individual embryos, all capable of developing into drupelets with their own central seed. If you’re bored after Christmas dinner, try separating a boysenberry into its constituent parts and counting them!  

Suitable climates and growing conditions

Bramble berries are a pretty hardy bunch, and can be grown right throughout New Zealand. I’ve been pleasantly surprised by how well boysenberries do in the humid climate on the South Island’s West Coast. Winter chilling requirements range from 200-700 hours for blackberries and 400-500 for boysenberries. Blackberries are a bit hardier overall, and within this group, thorny varieties are hardier than thornless. 

Plants vary in size and their growth habits. Some varieties grow semi-upright, whereas others have a trailing growth habit. For optimum production, a support structure will be necessary. A framework of horizontal wires spaced 50 cm along a fence line up to two meters in height is ideal, but if you have the time, nous, and materials, freestanding structures can also work well. You’ll want to allow 1.5 to 2.5 meters between plants.

Brambles fruit on wood in its second year of growth – canes produced in the current growing season will remain vegetative, only forming flower buds for the following year later in that first summer. There are a couple of different ways you can train your brambles once you have a support structure in place. In your bramble’s formative first year, it won’t produce a huge number of canes, so will be easy to manage. Cane production ramps up in subsequent years and you’ll need to be organized if you want to maximize your harvest and keep management simple.

Fan system


This is where you choose about a dozen canes and spread them out in a fan arrangement so there is about 25 cm of space between each when they reach the top wire – secure each to the top wires with a clip or tie to hold them in place. Cut each cane off about 30 cm above the wire, bend this extra 30 cm down, and tuck neatly into the adjacent cane to secure it. Allow 1.5 – 2 metres between individual plants.

Weave (or rollercoaster!) system


Gather bundles of two or three canes together and weave them up and over the top wire and back down over the next wire (or an even lower wire). Keep looping in rollercoaster fashion to use the length of the cane, or trim to a desired length. You can secure the wire using a few ties, but this is a more self-securing method than the fan arrangement.

Lots of the modern bramble cultivars are self-fertile and you’ll have no issues getting a crop off a single plant. Some of the trailing blackberries are self-sterile, so a few plants will be necessary. Bramble flowers produce copious amounts of nectar and as such, are much-loved by insects. A degree of wind pollination may also take place.

Because brambles fruit on canes produced the year before, don’t expect fruit until the second year. Fruit can be picked continuously over a period of about 3-6 weeks, depending on the variety. Boysenberries are ready late December to January, loganberries and tayberries slightly before this, and blackberries start late December to late January and fruit into autumn. Plants will produce for around 10 years, after which vigor and fruitfulness will start to decline. 

Brambles are easily propagated by root cuttings taken in early spring – simply dig up some root sections, and divide into pieces about 10-15 cm in length (making sure each piece has two or three buds on it). These can be planted directly in place in the garden (about 6 cm deep in soil) or potted up to be grown on. Suckers, where the buds have already started actively growing, can also be separated from the parent plant and treated the same way. An even easier method is layering, which we can induce artificially or simply happens naturally. This is where the plant’s trailing stems touch the ground and naturally form roots at the point where the stem touches the soil. To make this happen with human intervention, bury the shoot tips of some vigorous current-season stems in the ground in late summer – a new set of roots will form at this point and you can sever this new ‘offspring’ from its parent the following spring and either transplant it or pot it up to grow on.

Site selection and planting

Brambles can be planted from autumn to early spring. Choose a site in full sun to partial shade. Some form of shelter is a must, as brambles are susceptible to wind damage – for this reason, exposed coastal sites are best avoided. 

Being fairly hardy, any well-drained soil type of reasonable fertility will suffice. Brambles will often chug happily along in soils too poor for other crops, in this case, a handful of compost or sheep pellets in the planting hole won’t go amiss. Allow adequate space between plants (see training methods) to allow for good airflow, as brambles are susceptible to fungal diseases that thrive in high-humidity environments. You’ll also want good light penetration for optimal flowering and fruit ripening.

Culture and care

In terms of irrigation, bramble plants have roots fairly close to the surface, so adequate moisture is important, especially during fruit production time in summer – expect a marked decline in fruit quality and quantity in drought conditions.  

Brambles don’t have particularly high nutrient requirements – the ability of wild blackberries to thrive on waste ground gives a good indication – but a dose of balanced general fertilizer in spring and again in late summer won’t go amiss. Start with 100 grams per plant at establishment (split into two 50-gram applications across the season will be fine), increasing by about 100 grams per year until you reach 400 g/season for mature plants. Always apply prior to rainfall or water in the well.

Pruning

Once canes have fruited, they will look a bit old and tatty and it’s time for them to be removed at ground level. Once you’ve removed the worse-for-wear spent canes, train and tie in the new, flexible shoots all ready for cropping the following year. It’s good practice to burn the old canes in case pests or pathogens are lurking. Some growers prefer to keep canes of different ages trained to separate sides of their canopies to help make the distinction, with old grown and new growth trained in opposite directions but it’s entirely up to you. 

Pests, diseases, and what to do about them

Brambles are affected by fungal diseases that cause spotting and lesions on leaves and canes - Anthracnose is one of these. Botrytis (grey mold) may also strike ripening fruit affected by rain. Good canopy management (for adequate airflow and light penetration) and crop hygiene – removing and destroying diseased plant material will help.

The main insect pests you’re likely to encounter are raspberry bud moths, scale insects, and leafroller caterpillars. The latter like to stitch leaves up into a webbing-bound mass – digital biological control (removal and squishing via fingers) may be all that’s required to keep small populations in check.

It’s likely that in the home garden, you don’t want to embark on a heavy-duty spray program. For insect pests, try and maintain the natural diversity in your garden and provide a hospitable habitat for the natural enemies of common pest insects – try planting strips of buckwheat nearby, as its nectar-rich flowers are great for supporting populations of parasitic wasps that lay their eggs inside pesky leafroller and bud moth larvae. 

If you have major disease problems, you can try a lime sulfur spray in late winter (this will also help deal with scale insects) and a copper spray (e.g. Yates Copper Oxychloride) just as the buds begin to move to help with fungal diseases – follow the label directions. 

Birds will be your other (or should I say, the major) pest. Net your crop or face 100% loss. The most ingenious design I’ve seen for brambles is a compact support framework completely enclosed in a cabinet structure, overlaid with fine-mesh chicken wire. This one was complete with functional hinged doors for ultimate ease of harvest. If there’s a carpenter in your family, shoulder tap them now!

Varieties: My top picks

  • Blackberry – Karaka black: A New Zealand-bred hybrid whose parents are American blackberries. Thornless (or very close to it). Produces elongated, well-flavored glossy black berries from December to February. 
  • Boysenberry – Mapua: Blackberry/raspberry cross. A very vigorous New Zealand selection with long, trailing canes that will travel a great distance across your garden – support and a firm hand training them is necessary! A prolific cropper of large, sweet, well-flavored berries around Christmastime.
  • Tayberry – Lady in Red: I’ve seen the latter cultivar available commercially in New Zealand but my own un-named plants originate from an old garden in Canterbury so it’s worthwhile asking around for plants. A blackberry/raspberry cross, tayberry fruit is larger, sweeter, and more aromatic than that of the loganberry, another reasonably common blackberry/raspberry cross. Ripens early-mid December. Extremely thorny but worth it for the flavor.  

What to do with your crop

Abundant bramble berries are easy to preserve once you’ve eaten your fill of them fresh. They freeze exceptionally well (I advise freezing them in a single layer on a tray, then bagging free flow) and can be easily turned into jam as well – try a ratio of three parts sugar to five parts fruit for a bright, fruity conserve.

If you free-flow your fruit as opposed to freezing it in large blocks, you can easily remove small portions as you need them, e.g. just enough for a smoothie at a time. Try blending a few handfuls of berries into stewed apples and dehydrating them as fruit leather – berries are far too seedy to be enjoyed as a straight leather on their own, but lend a punch of flavor, colour, and antioxidants to blander fruit mixtures. The same applies to any baked dessert utilizing apples or pears for bulk – bramble berries just make it better.  

I think the best way of showcasing berries in a dessert is via Alison Holst’s beloved, American-influenced ‘Berry Buckle’ recipe. It’s basically a cake layer scattered generously with berries of your choice and topped with a cinnamon-spiked crumble topping. It’s a great combination of textures with an unmistakable jolt of sharp fruity flavour from the berries and can be made year-round with frozen fruit. Lois Daish has an approximation of it here. I suggest using a generous amount of Karaka blackberries and skipping the lemon and cinnamon in the base cake, preferring to just keep the spice in the topping. It is best eaten the day it’s made but leftovers can be refrigerated and reheated. 


Anna-Marie Barnes is an active member of the New Zealand Tree Crops Association who endeavors to grow and preserve as much of her own fresh produce as possible. When the weather’s no good for gardening, she can usually be found inside working on a batch of homemade cheese or soap.

The New Zealand Tree Crops Association is a voluntary organization promoting interest in useful trees, such as those producing fruit, nuts, timber, fuel, wood, stock fodder, bee forage, and other productive crops. Find out more about the NZTCA here: https://treecrops.org.nz/

Disclaimer: The information supplied above is of a general nature and provided as reference material only. In regards to pest and disease control, please consult your agrichemical consultant for suitable products, application rates and further region-specific information.

Image credits

Boysenberry plant fruiting - Image by Cara Shelton via pixabay.com

Boysenberry plant in flower - Image by Niceda Chavez Atencia via pixabay.com

Blackberries - Image by Christel via pixabay.com

Boysenberry fruit - Image by Cara Shelton via pixabay.com