We are planning to make 2026 the Year of the Cassis and will start to heavily promote the new blackcurrants from our breeding programme in mid-2025. Why do we believe that the unassuming blackcurrants are suitable for this? What are the characteristics that have recently made them a real sweet treat – provided, of course, that the new Lubera varieties are grown?
Looking back – blackcurrants as the Cinderella of the soft fruit family
What memories do you have of blackcurrants? Well, I remember the inconspicuous and completely unattractive row on the north side of the house, where only moss grew next to the blackcurrants. While I was still able to reconcile myself to some extent with the beautiful red currants, I couldn't manage it at all with the black ones. As a child, I couldn't understand how anyone could like something so nasty. The adults' talk only reinforced this impression: blackcurrants are sooo healthy; they must taste like medicine. Well, admittedly, they were slightly better than cod liver oil. But how could something be healthy that led directly to a sore throat with its sharp, bitter, almost gagging acidity? Could colds really be prevented with a fruit that hit the throat so directly? Was this a case of fighting fire with fire?
The Lubera blackcurrant breeding programme
Well, the childhood when we were forced to pick the blackcurrants behind the house during the summer holidays is long gone – in fact, half a century ago. But what has changed in the past 20–30 years that we now want to and can promote our Cassissima® berries as the Plant of the Year? Why and with what characteristics has the inconspicuous and de facto inedible Cinderella become a delicacy fruit that combines health benefits with enjoyment? The breakthrough in breeding began at Lubera around 25 years ago, when we started to incorporate Russian and Ukrainian breeding material into our crosses. Our breeder friend Martin Weber, who tirelessly supplied us with seeds and mother plants, played a major role at the beginning. Since then, we have continued to cross and select three to four generations, always looking for the following improvements and additional characteristics:
- Resistance to powdery mildew
- Fruit size up to 2 cm
- Absence of sharp acidity, rather a subtle cassis flavour
- More sugar, up to around 20 Brix
- Additional interesting plant characteristics
Resistance to mildew
Mildew is no longer an issue for Cassissima® varieties. For 10 years now, we have only marketed varieties with multiple resistance to American gooseberry powdery mildew. This has fundamentally changed the situation for currants as a whole: whereas 30 years ago, powdery mildew was the main problem, especially in blackcurrants, it has now been solved there, and meanwhile, our red Ribest® currants (which in turn improve standard varieties) are much more susceptible to powdery mildew than their black sisters. The powdery mildew problem with Cassissima® is definitely solved – that can now be checked off the list!
Fruit size is important – up to 2 cm in diameter
In the Lubera® breeding programme, we have almost quadrupled the fruit size of blackcurrants. From 5 mm to almost 2 cm. You could argue that sheer size is not the most important thing – but it is crucial for blackcurrants: size means more flesh and juice, more flavour, the taste buds are more quickly and completely surrounded by fruit juice, the tongue immediately feels the full sweetness with a little fruity acidity. What's more, the pulp now definitely dominates the seeds, which no longer make up 20% of the volume as they do with small fruits...
| Variety | Ø in mm | Rank |
| SJ 23-001 | 18.5 | 1 |
| Black Marble | 17.6 | 2 |
| Little Black Giant | 17.2 | 4 |
| Black Bells | 13.7 | 11 |
Table: Fruit sizes of some Lubera blackcurrant varieties.
Sweetness and mild cassis flavour
But what about the flavour? Here, the best breeding approach has been to select varieties and variety candidates that combine a lot of sweetness with a rather subtle cassis flavour. Recently, a customer wrote to me to say that he had a currant in his garden, but that he hadn't seen a fruit that big before and it tasted fruity-sweet without a cassis flavour. I was able to easily identify the picture as our 'Black Marble'® variety, which really is very similar to black marbles.
But why the subtle cassis flavour? Perhaps apart from England and the English, people are at least very divided in their assessment of the cassis flavour. If the flavour is rather subtle, it is much better received by the general public. Let's quickly compare the flavour and aroma of the highly praised blueberries: there's almost nothing there except sugar, a little acidity and perhaps a slight hint of vanilla...No one really has a negative allergic reaction to blueberries. Blueberries are actually always ok. We haven't got that far with the Cassissima® yet; a blackcurrant should definitely retain more character than any blueberry. But, like the blueberry, it should become a sweet fruit that can be eaten piece by piece out of a bowl and doesn't have to be made edible with spoonfuls of sugar first.
| Variety | Brix |
| sJ 515 | 20 |
| Black Bells | 18 |
| Little Black Sugar | 17 |
| Black Marble | 16 |
| Chuckleberry | 15 |
| Nimue | 14 |
| For comparison: average values for… | |
| Strawberries | 12–16 |
| Date grapes | 12–14 |
| Apples & pears | 10–14 |
| Blueberries | 8–14 |
| Blackberries | 8–12 |
Table: The latest varieties from Lubera score with Brix values of up to 20.
Less is more: the shift from strings to individual berries
As a child, I had to harvest blackcurrant strings and then they were destemmed. The new Cassissima® varieties (especially 'Little Black Giant' and 'Black Marble'®) are intended for single-berry enjoyment. We harvest them as single berries from the bush into a bowl – and that's exactly how they should be enjoyed. As an additional characteristic, the new varieties bleed almost no more or only very little at the break-off point where the fruit and the fruit stalk separate. We already have the first cultivars that no longer bleed at all.
Versatile garden use thanks to growth types and leaf colour
Lubera's Cassissima® breeding has also extended the range of uses for black berry bushes in the home garden. 'Blackbells'® and 'Black Marble' grow to a height of 120-150 cm, but 'Little Black Giant' and 'Little Black Sugar'® stop at one metre and can also be easily grown in pots. The 'Black'n'Red'® varieties, which combine sweet, black fruits with red to bronze-coloured leaves, are the ultimate ornamental shrubs. Red-leaved ninebark (Physocarpus) must sink into the garden soil with envy when they look at their beautiful fruit competitors...
From Cinderella to superstar
When I look back at the many types of fruit and berries that we work with at Lubera, blackcurrants have really undergone the greatest changes in the last 20 years: from the Cinderella of the berry world to the new fruit secret tip that is about to become a superstar. Cassis, as blackcurrants are known in Switzerland and the French-speaking world, have definitely become Cassissima®.
