In spite of nearly every tree fruit escaping spring blossom-killing freezes and bearing well this year, small fruit remain more certain to produce yearly crops. Red and yellow raspberries are the most reliable. Black raspberries are not widely recommended because of lack of cold hardiness; however roots do survive to try producing fruit again in two years time. This may change as better adapted and more reliable black raspberry varieties are introduced.
If several red and yellow raspberry varieties are planted, you can realize a harvest from midseason to frost. Summer-bearing Nova, Killarney and Boyne produced crops in July and now the fall-bearing types Anne( yellow), Autumn Britten (photo above right) and old standby, Heritage are ripening and can produce up till frost.
Raspberries are naturally a biennial, growing canes one year and producing fruit on those overwintered canes the summer of the second year. The problem comes with overwintering canes. In most parts of the Front Range this usually isn’t a problem. With summer bearing types, you wait until the canes are finished fruiting in the summer of their second year to remove them.
Post WWII breeding produced the fall-bearing types that grow canes and produce fruit in the same season, With no canes to overwinter, harvests are more assured and pruning is easier since they are simply cut to the ground after the fall harvest.
What are the problems with raspberries? Homeowners often ask why their raspberries that once produced well fail to bear a crop anymore. Raspberries will last about ten years and bear best in the first five years of that period. After that accumulated viruses carried in by aphids decrease production. The planting should be removed and new stock planted. Don't get plants from fellow gardeners because of viruses. Buy virus-free stock from reputable nurseries. Plant in new soil that has been amended with organic matter and drainage ensured often by building a raised soil bed.
More raspberry information is available in the CSU Extension raspberry fact sheet. Give them a try.
Photo credit: Autumn Britten fruit, Raspberry canes, Carl Wilson