Loganberry plants can be grown in 10- or 20-gallon planting containers; make sure that the container has at least four 1/4-inch drainage holes in the bottom. Additional holes can be drilled in the bottom of the container, if necessary. Cut a wire screen to fit snugly inside the container; top the screen with 2 inches of coarse gravel. Combine equal parts peat moss and sterile potting soil with 2 cups of perlite to create a moisture-retentive and well-draining growing medium for your loganberry. Plant the loganberry at the same level that it was growing in its nursery container.
Providing your loganberry plant with the appropriate amount of sunlight is essential to ensuring the production of healthy, flavorful berries. Position the plant in a spot on your balcony that receives six or more hours of direct sunlight per day, preferably in the morning. Though loganberry can survive in locations that get as few as four hours of direct daily sunlight, plants grown in low-light conditions will produce noticeably smaller berry crops.
Loganberry plants need frequent irrigation from spring through summer to maintain consistently moist soil. Water the plant generously once or twice a week to keep the surface of the growing medium moist to the touch; you may be required to irrigate more frequently in hot, dry climates. Reduce the frequency of watering in the fall and winter; water lightly when the top 2 inches of growing medium feel dry to the touch. Apply fish emulsion weekly during the growing season of the first year of growth, reduce the frequency of fertilization to monthly during subsequent years.
Prune your loganberry plant, as necessary, to remove diseased, damaged or dead branches or foliage. Use sharpened, sterilized pruning tools when pruning the loganberry to avoid spreading botanical diseases to your plant. Harvest ripe berries from the loganberry plant from August through September; harvested berries can be eaten fresh or used to make jams, pies and other desserts. In October, once all the berries have been harvested, cut the fruit-bearing branches down to the growing medium.