Growing fruit trees in the backyard isn't an option for many due to the space and care requirements. Berry producing shrubs, such as blackberry plants, grow easier than trees. Erect blackberry varieties grow well in large containers, making them suitable even if you don't have a suitable planting area in your garden. Winterizing the container grown blackberries is necessary to protect them once the temperatures begin to drop in late autumn.
Prune away the canes in autumn that bore fruit over the summer; blackberries only produce fruit on the previous year's new growth. Cut them off from the base and crown of the plant with sharp shears.
Move the blackberry containers to a sheltered area, such as a garage or garden shed, after the first hard frost in autumn. Storing protects them from the damaging freezing of winter, as well as from winter winds.
Mulch over the top of the soil in the pots before storing; the same is true if you must leave them outside over winter. Apply a 4-inch layer of straw mulch over the soil and around the canes to prevent frost heave from winter thaws.
Ensure that all existing canes are attached to any trellis system in place in the containers. Tie up first season canes to the trellis so they don't interfere with new growth in spring.
Cover outdoor-stored blackberries with a plant bag. Choose bag covers with ventilation holes or perforated bags. These prevent frost damage while allowing the plant to breathe. Tie the bag loosely to the base of the plant.
Remove the bags or bring the plants back outside in early spring once new growth begins or the buds begin swelling. Remove the winter mulch from the container once the soil begins to warm in mid-spring.