|By Richard Ashton
Successfully growing blackberries, raspberries and other fruit-bearing plants is often the result of good variety selection. Selecting the right types of blackberries and raspberries can eliminate the labor-intensive work of trellising, tying canes and removing floricanes after they fruit. But growing berries that mature in late summer and fall involves not only good variety selection but also non-standard orchard practices as well.
Most blackberries and raspberries fruit on two-year-old wood. The first year, the canes that emerge are called primocanes and they do not fruit. The second year, the same canes are called floricanes because they flower and fruit. Today, though, fruit breeders have found and developed primocane-bearing blackberries and raspberries. That is, they bear on the current season’s growth.
You can mow or cut the berry beds after they fruit and not worry about tying or trellising. You will need to put up temporary twine lines on both sides of the beds to keep them from trying to bend to the ground. This simple operation just takes a few minutes per bed, not the hours of cutting, removing and tying that is the standard operation for regular floricane-producing varieties. A simple tall stake, T-bar or post at the ends of the bed is all you need for attaching these twine lines, and they can be removed for mowing and easily replaced.
The culture for growing primocane-fruiting raspberries is a little different from growing primocane-fruiting blackberries. Raspberries tend to be less vigorous than blackberries, and the art of delaying fruiting can be easily accomplished with raspberries. Primocane-fruiting raspberries bloom and set fruit a little too early for our Texas heat. If left with no control procedures, they will bloom in late July and early August during the full heat of summer. To delay blooming, use a procedure called “tipping.” The most successful method of tipping is to remove one to two inches of the tips of the canes in early June or when the new canes reach three feet high. They should be tipped again in early July, regardless of height.
The first tipping will cause laterals to form. For the second step, tip the laterals as well as the new growth on the ends of the first-cut canes. As berries form on the tips of the new canes created by the tipping operation, you will have a heavier crop and, most importantly, will delay blooming until at least mid-August, when the heat is starting to abate. The berries should start forming in late August and early September, and continue blooming and fruiting until frost, if you use the double tipping. What will happen if you do not tip your raspberries? They will bloom in July, form fruit in the middle of our summer heat, and leave you with crumbly, dried-up berries. So tipping is nearly a must for primocane-fruiting raspberries.
For blackberries the tipping operation needs to be done when the new canes reach about 18 inches high and then again when the cut canes produce laterals that reach 18 inches. This operation needs to be controlled differently in various parts of Texas because growing conditions are not the same everywhere. To delay bloom time and produce more bloom tips for heavier crops, adjust your tipping times accordingly. It is best to do the second tipping operation before the first blooms form or just as soon as you see the first bloom bud. You want to make the plants wait until the hottest part of the summer has passed before they really start to bloom. You want fully formed drupes and juicy berries, and you can have them with this double tipping method of growing primocane blackberries.
Also, if you do not mow or cut primocane-fruiting blackberries in the second year, you will have a very good floricane crop of blackberries. This first floricane crop will usually be very heavy. To take advantage of this good floricane crop, use a rotation system that will allow you to do away with trellising, tying of primocanes and removing old floricanes.
Whether you have two beds or 200 beds, you can rotate your cropping. The first year you plant half your beds, do the tipping and grow your first primocane crop. You do not mow the canes at all that first year. The second year, you plant the other half of your beds. At the same time you let the first planting bear its first floricane crop. After the floricanes have finished fruiting, you let them produce a small primocane crop. You will not need to tip the new primocanes because bearing the floricane crop will delay the fruiting of the primocanes. When the floricane and primocane crops are finished, mow the first beds down. Then in the third year you will have a floricane crop on the second planting, and so on. No bed should ever go more than two years without being mowed or cut down if you want good production.
If you use this rotation method, you can have two good crops of blackberries a year (although from different beds). The primocane-fruiting blackberries make this rotation method possible.
So what about a rotation system for raspberries? It does not seem to be a good idea at this time to employ the rotation system for raspberries because they have less vigor and are susceptible to diseases. By mowing or cutting them every year, you greatly decrease disease pressure at the same time as you stimulate new growth.
‘Heritage’: Released by the New York State Agricultural Experiment Station in Geneva, N.Y., in 1969, ‘Heritage’ is the world’s leading primocane-fruiting raspberry cultivar. The red berries are medium size on very productive and hardy canes. It is one of the latest ripening primocane varieties, which is good for Texas. Fairly disease resistant or tolerant, it nonetheless does have some problems with mosaic virus complex and aphids under high pressure. The canes can reach seven feet in height, if left untipped. Tipping will maintain a good picking height.
‘Fall Gold’: Released in 1967 by E.M. Meador of the New Hampshire Experiment Service, ‘Fall Gold’ bears yellow-gold fruit on both primocanes and floricanes. The canes are vigorous and sucker freely. Very hardy, it is considered an ever-bearing variety. It is very similar to ‘Heritage’ in bearing time and vigor.
‘Prime Jim’: Because this variety has a higher chill requirement than areas of Central and South Texas receive, it is recommended only for North Texas. Not as heat tolerant as ‘Prime Ark 45.’
‘Prime Jan’: Because this variety has a higher chill requirement than areas of Central and South Texas receive, it is recommended only for North Texas. It is not as heat tolerant as ‘Prime Ark 45.’
‘Prime Ark 45’: A 2009 release from the University of Arkansas, this blackberry seems to fit the bill for most Texas growers. The berries are firmer and larger than the two previous releases, resulting in better shipping and storage qualities. It is more heat tolerant that either ‘Prime Jim’ or ‘Prime Jan.’
In 2008 Jim Kamas, Extension Horticulturist with the Department of Horticultural Sciences, Texas Cooperative Extension in Fredericksburg, received several trial blackberries from John R. Clark of the University of Arkansas. They included two primocane-fruiting blackberries labeled APF 77 and APF 45. In 2009, the University of Arkansas released APF 45 as ‘Prime Ark 45.’ To date APF 77 has not been released, but it looks good in the trial at Fredericksburg. Clark says that it may be released in the future. ‘Prime Ark 45’ is a winner and can stand our summer heat and bear well on primocanes.
Mowing or cutting of canes is usually done in November just after the first hard freeze. Cut at about two or three inches high, not completely to the ground.
Mulching the beds after they are cut is a good idea but not necessary in the warmer parts of Texas. By adding mulch at this time you will help suppress weeds and add organic matter to the soil. Organic matter is essential for good raspberry production and it is good for blackberries, though not quite as essential.
Heavy clay or calcareous soils are not good for raspberries. It is best to build raised beds and add a sandy loam soil and lots of organic matter if you have these types of soil. Blackberries will tolerate heavy clay, but they must contain plenty of organic matter and must be kept moist.
The best soil for both of these berries is a loamy soil containing organic matter.
Raspberries need a well drained soil, but one that holds moisture. By adding organic matter you can usually achieve the ability to hold moisture without impeding drainage. Mulches such as hay, leaves, bark, sawdust or commercially produced mulches are good for the organic matter they contain. It will take nearly a year to really get the mulches broken down into the humus the plants need. So add some mulch every year for continuing production.
Frequent watering is necessary for good production. The ground must be kept moist in the summertime to avoid stressing the plants. During the late fall and winter just a little water in dry periods, as necessary.
For raspberries a little shade in the afternoon is beneficial. Try planting on the east or northeast side of some trees or a structure to avoid the afternoon heat of summer. Some growers use shade structures over raspberries. In contrast, blackberries need full sun.
A soil test should be done to determine soil nutrients and any deficiencies should be corrected. As a general rule, 30 to 70 pounds of actual nitrogen should be added per acre each year, depending on row spacing of established plants. For new plantings, an application of 10 pounds of actual nitrogen per acre about six weeks after planting is usually sufficient to get the plants off to a good start.
Raspberries can also be grown in large containers such as the 7-to-10 gallon sizes. They will fruit well in containers and can be put on a patio or next to a house or outbuilding. It is best to use a container drip system if attempting to grow in containers as they do need regular moisture. Most potting soils are good for container culture. Just add a little perlite and mulch every year to keep the roots aerated and fed.
Primocane-fruiting raspberries can and are being grown in commercial greenhouses with staggered fruiting times so that the growers have year-round production. This practice is common in Europe. ‘Heritage’ is the predominate variety in this culture.
Richard Ashton is the author of several books on fruit growing, including The Incredible Pomegranate — Plant and Fruit; Jujube — The Chinese Date; Sweet Cherries — For Southern Orchards and Plums of North America. They are all available from Third Millennium Publishing on the internet at www.3mpub.com/ashton