One of the things i look for when deciding on a fruit tree is that it has to be a little bit special than something you can easily find at the supermarket. Because why go to all that trouble to grow something that when its in season will probably be quite cheap & readily available. This is why i love Blood Orange trees. For starters they are very rarely available to buy in stores and when they are, they are imported and always seem a bit past their prime. Yes they are Oranges, but slice them open and you’re rewarded with a surprise – deep, almost purple flesh and a distinct sweet Raspberry flavour. The fruit is usually slightly smaller than most Oranges.
The distinctive dark flesh color is due to the presence of anthocyanins, a family of antioxidant pigments uncommon in most Citrus fruits. The flesh develops its characteristic maroon colour when the fruit develops with low temperatures during the night. Sometimes there is dark colouring on the exterior of the rind as well, depending on the variety of blood orange.
The three most common types of blood oranges are the Tarocco (native to Italy), the Sanguinelli (native to Spain), and the Moro (native to Sicily). The Moro is the most pigmented with an almost black colouration and also has the strongest aroma & richest flavour. While also pigmented, Cara Cara navels have red pigmentation too but this is based on Lycopene, not anthocyanins like Blood Oranges. I have planted at home : 3 Moro, 1 Tarocco, 1 Sanguinelli and 2 Cara Cara. Of these i have only had the Tarocco fruit and it was moderately coloured but took until late in the season (August) to colour up. It seems the Blood Oranges trees take longer to fruit than some other varieties for instance my oldest Moro is just fruiting this year after 4 years!
So why we don’t see Blood Oranges commercially grown in NZ? I think this is partly due to the degree of difficulty in growing them. To deliver a true blood orange, we need to have the right environmental conditions to help build the levels of anthocyanins. Half the battle is growing them in the right temperament, in a lattitude that provides harsh, dry and hot summers as well as cool, nippy winters. The next issue is to then choose a suitable location that will provide maximum temperature differential during autumn & winter. What this basically mean’s is that to grow Blood Oranges successfully and to their fullest potential, they need to be grown in a location that will provide almost freezing night temperatures as well as high day temperatures. In a technical standpoint, the stress the tree endures during this weather process forces the tree to develop the much needed anthocyanins. Not many places that are suitable for Citrus meet this quality. That said, in my garden in Ponsonby, NZ, i was still able to produce Blood Oranges with a good degree of pigmentation last year with my Tarocco. So i look forward to what i can produce when the Moros gets around to fruiting. My theory is they need almost a freeze in winter (i.e.: around 0 degrees Celsius for a few nights at least) to colour up as i checked the Bloods in about June and they were sweet & ripe with no colour. But left until August after a few cold weeks they had good colouration.