By Anna-Marie Barnes
This article was originally published on lifestyleblock.co.nz.
Most Kiwis are familiar with blackcurrants – those pungent, tart, vitamin C and antioxidant-loaded black spheres (even if it is via over-sweetened Ribena drinks consumed as a child). Blackcurrants are cold-hardy and prolific, ripe about now in mid-December, and certainly worth having in the garden for cooked desserts, cordials and preserves – though in my experience, only the toughest of the tough can eat mouth-puckering blackcurrants fresh in any great quantity. Did you know that blackcurrants have some lesser-known relatives which are much milder on the palate and can even be eaten as a fresh dessert fruit? Enter the red and white currants…uncommon commercially (there is one commercial three hectare planting near Ashburton, grown for Barker’s of Geraldine) but a useful, easy-care crop for the home garden.
Red and white currants: a short family history
Currants belong to the Grossulariaceae (the gooseberry family – currants and gooseberries are cousins) and more specifically to the genus Ribes. Blackcurrants are domesticated varieties of their wild ancestor, Ribes nigrum, which is native to Europe and Central and Northern Asia, including Siberia. Redcurrants descend from Ribes rubrum (and are also known as R. sativum, R. petraeum and R. vulgare), also a native of similar geographic regions – with white currants simply being albino redcurrants, with one distinction – they lack the vitamin C content of their more colourful siblings. Red and white currants have the advantage of jewel-like looks and suitability for use fresh, with minimal preparation. They also ripen before blackcurrants, but are somewhat more palatable to birds, so you’ll likely need a net if you want a sizeable harvest.
To give some historical context, red and white currants appeared in British gardens in the 1500s – well before blackcurrants, which only came on the scene in the 1700s. The fruit was given the name ‘currant’ in recognition of its superficial resemblance to the small dried fruit produced from grapes, the name of which is itself derived from Corinth, a city in Greece well known for its grape production over the centuries. The initial redcurrant variety introduced was a small-fruited cultivar known simply as ‘Common Red’ which was eventually surpassed by a Dutch variety, the ‘Great (Dutch) Red’, with much larger fruit, introduced in 1611 by the great plant collector John Tradescant the Elder (yes, the Tradescant who gave his namesake to that now greatly detested ornamental-turned-noxious weed, Tradescantia fluminensis, and all its terrible relatives).
Back in Tradescant’s era, redcurrants were far more popular compared with current (ha!) times, when blackcurrants seem much more common in our domestic gardens than red or white. It seems that the blackcurrant’s pungent foliage and robustly-flavoured berries sadly consigned the fruit largely to medicinal purposes, although its high vitamin C content was held in high regard. Throughout the Second World War, every schoolchild in Britain received a free supply of locally-produced blackcurrant juice, with the fruit thriving in the region’s cool climate.
In further blackcurrant lore, you’ll probably be interested to know that less than 0.1% of the American population has ever tried a blackcurrant. Why? Despite cultivated blackcurrants travelling to the USA with British migrants in the 1600s and being grown on a reasonably large scale for some time, that all changed in the early 20th century. Blackcurrants were found to be a host of white pine blister rust (Cronartium ribicola) (WPBR), for which there was no remedy at the time. The plants posed a huge risk to the burgeoning timber industry (white pine being a keystone species) and as a result, the federal government banned the propagation, cultivation, sale and transport of blackcurrant plants. The most WPBR-susceptible Ribes varieties were found to be blackcurrant species, so existing areas under cultivation were obliterated by spraying, effectively eliminating the fruit from the country. Native North American currant species (a component of natural forest understories) appear to have escaped (or at least survived) this extermination period, due to being less-suitable hosts for the fungus. With the advent of rust-resistant currant cultivars, the ban on currant cultivation was lifted in 1966, but to this day some states retain some degree of restriction, meaning in some areas even backyard growers need to obtain permission from local authorities to grow the fruit at home. Red and white currants and gooseberries, not being as susceptible to WPBR, seem to be treated with much less caution in modern times.
Suitable climates and growing conditions
With cool-climate Northern Hemisphere origins, red and white currants do better in colder areas, where a decent winter with frosts will provide the 800 to 1500 hours of winter chill required for the bushes to set fruit. They should grow well throughout the South Island and lower North Island and do have a slightly lower chill requirement than blackcurrants. Fruit set is reduced where winter chill is insufficient, hence growers in the Far North may struggle. Cool, humid summers are ideal for the Ribes ripening phase, which is why much of New Zealand’s commercial blackcurrant cultivation is focused on the southern districts. They even grow well on the West Coast of the South Island, where other fruit crops may struggle to ripen.
Site selection and planting
Currants are one of the few fruiting plants which thrive in partial shade. A sheltered position, open to the morning sun but shielded from the heat of the afternoon is ideal. In my family’s orchard, the currants grow and produce happily in the shade of several mature apple trees. You could also utilise the south side of a shed or other garden structure to provide respite from afternoon sun. Aim to leave one to two metres between plants. You can expect mature plants to attain a height and spread of around two metres or more in either direction.
Although currants are tolerant of a wide range of soil conditions, including heavier clays, well-drained, fertile types are best. Currant bushes should ideally be planted in autumn (May is ideal) and definitely no later than August, as the new season’s growth commences early in spring.
Culture and care
Currant bushes are shallow rooted, so watering is key at certain growth stages. Keep plants well-watered, especially in sandier soil types, but avoid overwatering. The plants flower in spring and are insect-pollinated. Ensure the water is kept up from flowering right through the fruit development stages to harvest, which is usually from mid-December to January. After harvest, water requirements decrease. A layer of organic mulch will help retain soil moisture and keep the plant’s roots cool in the height of summer.
Currants are not gross feeders, so a single application of general fertiliser in the spring is sufficient for year-round maintenance. Allow 350 g for a mature plant (around three or more years of age), reduce this amount proportionally by taking the age and size of your plants into account.
While currants grow readily from seed, if you are not purchasing nursery-grown plants, propagation from cuttings is the quickest and easiest method. Cut 20-30 cm lengths of either semi-hard wood in autumn, or dormant hardwood in winter. These can be planted directly in to the ground where you wish the plants to grow, or into pots – currants produce roots so readily there is even no particular need to use a specialist propagation mix or a rooting hormone, but neither of these will do any harm. Bury two thirds of each cutting in the growing media, leaving just two or three buds above ground.
Mature bushes will produce around 4.5 kg of fruit, which is best harvested by picking whole sprays of fruit with the stem intact. Use the tines of a fork to zip the currants off the stems. If you are finicky, you can also do what my Mum does and ‘top and tail’ the currants to remove the papery calyces and any stem remnants, trimming them off with a small sharp knife. Superior results require dedication to the cause! Currants are not long-keepers in fresh form, but freeze extremely well.
Red and white currants have quite different pruning requirements than blackcurrants. Blackcurrants fruit on one year old wood, whereas red and white currants fruit on spurs produced on more mature, two year old plus wood, hence older branches are kept for several subsequent years. Don’t expect a crop in year one! The structure of the plant varies as well, with blackcurrant branches arising directly from the ground while redcurrants have a short trunk. Aim for a vase shape with an open centre to allow adequate airflow.
At planting, cut the main shoots back to about half their length. New shoots will grow from these and will also produce lateral growth. A year later, again cut the main shoots back by half and trim the laterals to about two buds (five centimetres). These laterals should produce fruit every season, and then be pruned back to ensure continuous fruiting. In subsequent years, follow the formula of cutting leaders back by half and trimming laterals to one or two buds. As the leaders age and become less productive, they can be replaced with vigorous new shoots (plan to remove and rejuvenate the leaders after three years of age). As with all winter-dormant deciduous fruiting plants, aim to complete your pruning before the new spring growth begins.
Pests, diseases and what to do about them
The number one currant pest (apart from greedy birds) is the currant clearwing moth (Synanthedon tipuliformis). The adult moths are an ornate wonder of nature, truly a sight to behold. Sadly, their offspring are bad, bad news for your currant crop. Adult moths lay eggs on the canes during spring and summer, which then hatch and the larvae bore into the shoots, tunnelling them out. Unchecked, they are capable of destroying the whole bush. If you notice any damage, usually indicated by dieback or unhealthy looking branches, cut some stems open – if you see hollow, black centres instead of healthy green-white pith, you have resident currant clearwing larvae. Prune the infested shoots back to healthy material, seal with pruning paint and burn the affected material immediately. Commercial growers use pheromone ties to disrupt the adults’ mating cycle.
Other pests present in New Zealand that can have a detrimental effect on currants in New Zealand are blackcurrant gall mites (Cecidophyopsis ribis), scale insects, two-spotted mites, leafrollers and the lettuce-currant aphid, Nasonovia ribisnigri.
Fungal pathogens include cane dieback caused by Botryosphaeria ribis, and flower blight and leaf rot by Botrytis cinerea. Gooseberry mildew (Podosphaera mors-uvae) can also be a problem, especially in humid climates. The home gardener’s best defence against fungal disease is to maintain an open canopy with good airflow and avoid overwatering.
Varieties: My top picks
You might end up with an unknown red or white currant variety, especially if you take cuttings from a friend or relative’s plant. Incredible Edibles don’t specify cultivars but stock both red and white currant plants. Southern Woods in Christchurch also stock an unnamed white currant and Gloria de Versailles redcurrant (see below).
Waimea Nurseries offer two redcurrant cultivars:
Gloria de Versailles – vigorous, upright plants with good crops of large red berries borne late December to February.
Myra McKee – a prized home garden selection, good crops of medium-sized berries December to February.
Early-harvest redcurrants have a sharp, tart flavour and are ideal for jams, jellies and sauces. Being high in pectin, they are an excellent addition to harder-to-set jams, such as raspberry or strawberry. Leave the fruit on the bush a little longer and you’ll have sweet, juicy dessert fruit – perfect for serving with ice cream and for decorating cheesecakes, mousses or other dairy-based desserts. I’m sure their jewel-like beauty would be perfect atop a Christmas pavlova, offering a little tangy offset to all that sugar and cream.
Redcurrants grow very well and are extremely popular in Scandinavia, where a type of fruit cordial or syrup, saft, is made from the fruit. Another redcurrant condiment, rårörda röda vinbär, literally stirred raw redcurrants, is a mixture of fresh redcurrants and sugar mixed together (the ratio is 2 cups of redcurrants to ½ cup of sugar – stir together and leave to macerate for a couple of hours. Store any leftovers, covered, in the fridge for up to a week). It is served alongside meat dishes and as a dessert topping.
Redcurrants have an affinity with citrus, orange in particular, and the two can be combined to make a refreshing sorbet. The also sit well with melon – how about a fruit salad of redcurrants and diced honeydew melon dressed with orange juice and/or liqueur to brighten your Christmas table? At one point, Barker’s of Geraldine produced a sparkling redcurrant, rhubarb and rosehip drink and a redcurrant, cranberry and pomegranate syrup but I’m not sure if they are still available.
Redcurrant jelly is a popular accompaniment in its own right to many meat dishes (especially game) and cheese, and also forms the basis of the well-known English citrus-spiked Cumberland sauce, which is also served alongside cold meats and game pies. Fresh redcurrants are a common component of the ubiquitous English ‘Summer Pudding’, but I’m a vociferous opponent to soggy bread in any shape or form, so you won’t find one in my kitchen – ever!
Pearl-like white currants can be used in place of redcurrants in any of these recipes – they are sweeter than red or black, about as sharp as a well-ripened gooseberry, but obviously lack the bright colouring of their red siblings. Instead of one of my own recipes this month, here’s a link to a beautiful white currant cake, which really showcases the fruit in all its ivory beauty: https://tastebotanical.com/white-currant-cake/
Anna-Marie Barnes is an active member of the New Zealand Tree Crops Association who endeavours 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 organisation 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/
Redcurrant fruit – LMoonlight, via Pixabay
Redcurrant desserts – Marina Davydenko, via Pixabay
White currant fruit – Ascetik, via Pixabay.