Double Cropping Raspberries
For growers who are looking to extend their harvest season without planting several varieties, everbearing varieties are an excellent option.
When selecting a variety of raspberries, one of the first questions asked of growers is “what is your desired harvest time?” Are you looking for summer production, fall production or both?
True commercial everbearers can produce both a primocane and floricane crop effectively, double-cropping. Double-cropping increases the overall yield while also extending the harvest season. Several primocane fruiting varieties also offer good summer crops in addition to their normal fall harvest. Additionally, there are some traditionally summer-bearing varieties which also produce a good quality fall crop, Prelude and Nova are excellent examples.
Double-cropping can be a good option for most growers in zone 5 or warmer. The use of high tunnels can drastically increase yields, up to 50% increase, as well as extend the season and provide better quality fruit. For growers in cooler climates, use of a high tunnel can be necessary to extend the growing season when doublecropping.
Good cane management is essential for maximizing yields. Trellising plants is also necessary to maintain high yields and reduce loss and breakage from wind, crop load, and winter damage. Attaching canes to the trellis wire with clips locks the canes in place, thus reducing potential damage from wind and fruit weight and increasing winter protection. After summer harvest, floricanes should be removed at ground level and primocanes can be thinned to 6 – 8 canes per linear foot of row. Primocanes should then be clipped onto the trellis wires. In late fall, when plants reach or are close to dormancy, cut canes to 4’ – 5’.
VARIETIES TO CONSIDER FOR DOUBLE-CROPPING:
Himbo-Top® is a vigorous mid-season primocane variety that has good winter hardiness and has shown good tolerance to Phytophthora root rot. It has very large berries with a lighter color, which does not dark after picking. Given its vigor this variety is a good option for organic production but should be thinned and trellis for best results. Care should also be taken not to overapply nitrogen as it can cause soft fruit.
Joan J is a very high yielding, thornless variety which primocane crop ripens a week after Polka. Its large fruit have a dark color when fully ripe and will darken after picking so they should be picked every other day. Fruit can be picked under ripe to increase shelf life but with a loss of flavor. This variety is an excellent choice for high tunnel production.
Prelude is often treated as a floricane but in fact it does produce a good quality late primocane crop in zone 5 or warmer. The earliest producing floricane variety, Prelude has excellent vigor and winter hardiness. Fruit is medium-large, roundconic with very good flavor.
Mapema® U.S. Plant Patent #27,182
This is the earliest ripening variety from ABB, with harvest similar to Polka. Mapema produces over a long season. Berries are large and firm with very good flavor, however the color can be a little dark. In zones 6 or warmer, especially when grown in a high tunnel, Mapema produces an excellent floricane crop.
Imara® U.S. Plant Patent #23,916
An extremely productive primocane variety from ABB that begins production shortly after Mapema, about 7 – 10 days. Fruit is well displayed and release easily when ripe. Berries are medium-large, bright red, with very good flavor.
Kweli® U.S. Plant Patent #23,915
A mid-season primocane variety from ABB, which begins fruiting just after Imara. With very high yields of large, bright fruit with excellent flavor and shelf life make Kweli an excellent choice for shipping as well as local sales. Due to its vigor, care should be taken to exclude excess canes to keep plants more open.
Kwanza® U.S. Plant Patent #23,914
Currently our most sought-after variety for southern growers and the west coast. The latest ripening varietiy from ABB, Kwanza begins fruiting about 3 weeks after Polka. The characteristics that make Kwanza a top variety include its large fruit size, good flavor, exceptional shelf life and ease of picking. Fruit also does not darken noticeably after harvest.
