The following excerpt is from Blake Cothron’s new book, The Berry Grower: Small Scale Organic Fruit Production in the 21st Century. (New Society Publishers, May 2022) and is reprinted with permission from the publisher.
The king of berries stands tall and strong on the micro farm, and easily puts out an encouragingly high yield of luscious, plump, juicy fruit when well grown. Cultivars vary a lot these days and are very specific in terms of growth habit, ripening time, berry quality, etc., so choose very carefully.
Blackberries thrive in hot and humid summer conditions. Certain cultivars and subspecies, especially raspberry/blackberry hybrids are best adapted to the cooler conditions of the PNW and coastal California, and some are adapted to low-chill areas and even subtropical conditions. Many species grow wild across the USA. In the Eastern USA most wild blackberries are small-fruited, fairly low quality and seedy, but still harvested on a very small scale (and make great blackberry cobblers!). In the PNW many of the wild ‘Himalayan’ blackberries and wild hybrids are large and quite luscious.
Types of Modern Blackberries
First let’s start with the three main types of blackberries. They are differentiated by their starkly pronounced, varying growth habits. Here’s some lingo to learn:
These are the true “blackberry vines.” They vary in vigor and size but the most vigorous can grow 9 to 12 feet ( 2. 7-3.6 meters) long or more in a single growing season. They are productive but need careful management and a stout trellis system because single vines and fruit load can weigh 50 pounds or more. Not the best choice for the micro farm or small backyard, but can be utilized if necessary. These need lots of space, 8 feet (2-4 meters) or more between plants, and careful pruning and training to keep them in bounds and productive.
These have more vertical “spine” to them and make thicker, more sturdy canes that stand erect more like a raspberry-straight and tall. However, the upper half of the plants eventually vine somewhat, and the growth is very vigorous. ‘Semi-Erect’ seems to be a somewhat synonymous term for this type, but may also be its own category, with semierect cultivars having less trailing top portions and slightly less vigor. Otherwise not a lot of important differences apparently exist between the two, except that the University of Kentucky claims differences in yield estimates.
Easier to manage and generally less vigorous than trailing blackberries, makes them preferable when the option is available. They require stout trellising. Modern breeding (except in the PNW) is focused primarily on developing semi-trailing/semi-erect or erect cultivars. They need about 6 feet (1.8 meters) between plants. Semi-trailing plants are considered the highest yielding types, with 9000 pounds per acre possible.
These are the sturdiest and most shrub-like of all. The stems are rigid, thick and almost woody. They have medium vigor. Erect blackberries are a great choice for the micro farm and backyard grower. Trellis growing is best, but they can be adapted to non-trellis growing. For the backyard grower, large ringed metal tomato cages will suffice. They will not safely free-stand with no trellis; winds and storms will topple them over, or just the weight of the plant itself. These compact plants need only about 4 to 5 feet (1.2 to 1.5 meters) between plants.
For market growers, I recommend planting erect or semi-erect, thornless cultivars only. They are more compact, easier to grow and support, and still produce excellent yields and berry quality.
That’s not all, there’s also:
Self-explanatory; however, blackberries can be very thorny, with sharp, reticulated thorns. Most market growers are not going to want to grow thorny blackberries. However, if you live in a very heavy deer pressure area and lack fencing, these can be capable of repelling most deer. The larger ones make excellent security hedges. And they often are higher-yielding than thornless blackberries. Many commercial growers still grow thorny blackberries for their high quality and excellent yields. Just wear gloves and be prepared to get pricked and scratched when pruning and harvesting.
Zero thorns. What a horticultural achievement! In former days, thornless cultivars were considered inferior in taste and quality to thorny cultivars and they were inferior, being somewhat sour and seedy. That situation has changed with modern breeding in the last 25 years, and many newer cultivars are as good or better than the thorny cultivars, though perhaps not quite as productive. Much easier to manage, prune and harvest. Semi-thornless cultivars also exist.
Yet there’s more. Blackberries also are divided into the two following fruiting habits:
These blackberries produce flowers (and thus fruit) only on year-old canes. Meaning, year one: plants produce canes. Year two: those canes flower and fruit. This cycle continues, with every year new canes growing and maturing, and the following year they flower and fruit. (Then that cane dies and is replaced by the new ones growing around it, which will flower and fruit next season.) The mix of primocanes and floricanes assures production every year. Until recently this was the only type of blackberry available.
Reliable, productive, and dependable harvests where adapted and by far most cultivars are floricane producers.
Extreme winter weather and winter deer browsing can damage or destroy susceptible plantings. Pruning and training is required.
Welcome to the new frontier in blackberries. Another horticultural achievement thanks to the University of Arkansas blackberry breeders. Year one: Canes emerge in spring, grow a certain height, around 4 to 5 feet’ (1.2 to 1.5 meters), then flower and yield a crop. Year Two: If you pruned off the top growth that fruited in year one and allowed the canes to overwinter, you can harvest an early summer (floricane) crop, after which the cane is finished fruiting and dies. In late summer the new primocane crop ripens from canes that emerged in spring. Two crops possible per year. There are thorny and several thornless primocane cultivars available, with new ones currently being released by University of Arkansas.
Potentially no winter kill or deer browsing in winter: you just mow all the vines down after harvest. They will return in spring and yield a crop that same summer on the primocanes. Repeat. You will “only” get one harvest per season (late summer/early autumn) that way. Or, you can overwinter the canes and have two picking seasons (spring and late summer) from both the primocanes and the floricanes. The recent cultivars produce very large, tasty fruit.
Hot, very dry summer conditions destroy primocane flowers, thus it diminishes or eliminates any harvest of primocane berries. This occurred with ours in the summer of 2019. Primocane blackberries do not set fruit properly in extreme or intense heat (90+ degrees F, 32+ degrees C). The mid-late summer flowering of the primocanes may prove an issue for that reason and also SWD flies can target late ripening berries. So, be careful when considering primocane blackberries if your late summers’ temperatures are often 90+ degrees F (32+ degrees C) or SWD pressure is intense.
So, now if you read that a blackberry cultivar is semi-erect, thornless, and floricane producing, you should know exactly what that means.