A popular summer fruit widely grown in the home garden, blackberries (Rubus spp.) are dependable and fairly easy to grow. Each blackberry plant can bear up to 20 lbs. of fruit, according to North Carolina State University Extension. Blackberries are ripe when the berries turn a dull, black color. They ripen over a 2 to 3-week period. Blackberries keep longer and better in the refrigerator if they are picked when still shiny, although they will be less sweet than fully ripe, dull-looking berries. Planting blackberries properly will help ensure a bountiful harvest.
Choose a spot in full sun with deep, rich, well-drained soil. Ensure blackberries have plenty of room to grow to maturity, at least 4 feet of space on either side of the row.
Improve the soil with the addition of peat moss and compost. Spread a 2- to 3-inch layer of peat moss and a 1- to 2-inch layer of compost on the surface of the soil. Incorporate these amendments into the soil by digging them in with a garden shovel or tilling in with a rototiller. Rake the surface of the soil smooth.
Space semi-trailing or erect varieties of blackberries 3- to 4-feet apart and trailing varieties 6- to 8-feet apart. Dig individual holes large enough to accommodate the spread out roots of the plants.
Place the roots into the pre-dug holes and spread them out evenly within the hole. Ensure the plants are growing at the same level as they were in the nursery. Back fill the hole with soil, gently tamping down the soil with your foot as you go.
Set a soaker hose alongside the row of blackberry plants, about 6-inches from their base, and allow it to water them in. Let the hose run for about two hours to thoroughly moisten the soil to the depth of the roots. Provide blackberries with the equivalent of 1 inch of rainfall per week during the growing season.
Fertilize blackberries about a month later, when they have recovered from transplanting and are in active growth. Scatter about 3 to 4 oz. of 10-10-10 granulated fertilizer around the base of each blackberry cane.
Erect a trellis to support the blackberry canes as they grow taller. Position two wires, one 3 feet off the ground and the second one 5 feet off the ground, fastened to secure posts at the end of each row.