Blackberry canes grow well in Polk County, Fla., where the climate is desirable for their growth. The climate in the area produces hot summers to assist with fruit production and mild winters to prevent cane damage. The soil type in central Florida and Polk County is mostly sand-based, with some areas having a slight clay or peat. Blackberries in this region benefit from amendments to improve the soil quality, making it similar to a sandy loam.
Select a planting location for the blackberry garden that is close to a water source, in full sunlight and has air circulation to prevent disease. Do not plant blackberries in a location that has previously grown verticillium fungus-susceptible plants, such as tomatoes, potatoes and eggplants.
Amend the planting soil by adding 3 to 4 inches of organic compost or peat moss to sandy or clay soils.
Test the soil pH, as blackberry canes grow best in an acidic soil that has a pH of 5.5 to 6.5. Add amendments as recommended by the soil test and work them into the planting area two weeks before planting.
Build planting rows that are 4 feet apart. Install an irrigation system in the rows or lay soaker hose to irrigate the canes during the hot, dry summer months in Florida.
Dig 3-inch deep planting holes that are wide enough to accommodate the spread of the blackberry roots. Set the roots into the holes, gently spread them out and cover them with soil. Gently tamp the soil to hold the canes. Space blackberry plants 2 feet apart in the planting rows.
Water the canes immediately after planting to promote root growth and establishment. Soak the soil to a depth of 4 to 5 inches. Continue to water the canes so they receive 1 to 2 inches of water each week during the growing and fruit production season. Monitor the soil moisture and apply additional water during period of drought to prevent the soil from drying.
Prune the canes to a height of 4 inches after planting to promote new, strong branch growth on the canes.
Place a 3-inch layer of straw mulch over the planting rows and around the canes to assist with soil moisture retention and to limit weed growth.
Apply a 10-20-10 fertilizer to the soil around the blackberry plants each spring after the first year of growth. Follow the label instructions for application details.