Prime-Ark® Horizon, Is a new primocane-fruiting variety to expand grower options for this unique blackberry type. It has very high yield . Berries are large and firm, with postharvest similar to Prime-Ark® 45. In Arkansas, the floricane crop first harvest date is June 12, near that of Ouachita. Primocane first harvest date is August 4, The primocane-fruiting period extends into mid-October, 8 days longer than Prime-Ark® 45 and 19 days longer than Prime-Ark® Traveler. Primocane fruiting period of over 60 days. Berry size 7.8 overall average but can be larger than 10 g for floricanes and average 7.3 g for primocanes. The floricane and primocane average weights are much closer than other primocane-fruiting varieties, suggesting more berry weight stability in summer heat during primocane flowering and fruiting. Yield: Very high yield potential on floricanes, and crop control with pruning is advised to balance crop. Floricane yields have exceeded 30,000 lb/acre, but can be less depending on the degree of primocane fruiting the prior year. Primocane yields range from 3000-9000 lb/ acre depending on year and environment. : Flavor has been rated good with light aromatics. average is 10%, with titratable acidity of 0.92%. Postharvest: Storage for 7 days has been comparable to Prime-Ark® 45 in reddening/reversion. Prime-Ark® Horizon freedom blackberries retain excellent firmness in storage and the firmness, leakage and decay have been among the best measured in the Arkansas program. Plants: Prime-Ark® Horizon plants have shown good health, except when excessive floricane yields were experienced that resulted in reduced floricane leaf size as well as upward leaf curling. No orange rust nor anthracnose was observed on Prime-Ark® Horizon. Winter hardiness has been comparable to Ouachita, and has shown very limited winter injury to a low of 1F. Chilling requirement is unknown, but is anticipated to be approximately 300 hours