Blackberries (Rubus spp.) , which grow best in U.S. Department of Agriculture plant hardiness zones 5 through 10, are usually propagated through cuttings or division. This technique provides an specific replica of the berry bush. It is possible to develop blackberry shrubs by planting seeds, however, the seedlings change in features. The ideal time to plant young blackberry seedlings outside is in September, but the germination process starts six months before.
Harvest the blackberry fruit. Use fresh berries to gather the seeds, not dried fruit. The germination rate drops once the seeds dry out. Place the fruit in a blender, then pulsing on low until the seeds and fruit independent. Highlight the berries from the juice, and select the seeds from the pulp with tweezers.
Examine every one of the seeds for scratches or nicks. Scratch any pore without damage with a sharp knife. Scarification helps break the powerful seed dormancy surrounding the embryo.
Put the blackberry seeds in a resealable plastic bag along with a handful of moist peat moss. Seal the bag, and put in a refrigerator with temperatures around 33 to 35 degrees Fahrenheit. Keep the seeds cooled for 12 to 16 weeks.
Fill seed trays with seed starter dirt, and distribute the blackberry seeds on top of the ground. Lightly cover the seeds with soil, and set in a warm location. Blackberry seed germination does not want bright light because the seeds are covered with dirt. Mist the dirt with water in a spray bottle when the soil starts to dry out. Once seedlings start to sprout, move the tray to a room with bright light.
Remove the weeds from a planting area in full to partial sun. Pick a place with good drainage. Spread a 3- to 6-inch-layer of well-rotted compost over the planting area. Dig the organic material to the ground with a shovel. Utilize the compost to the top 8 inches of dirt. This provides that the blackberry plants a great source of slow-release nutrients. Smooth the ground with a rake.
Dig holes with a hand trowel only as deep and wide as the seedlings’ root balls. Space out the holes 4 to 6 feet apart. Put the seedlings in the holes, and fill with dirt. Gently firm the soil around the brambles so that they stand up. Space the rows 10 feet apart.
Water the ground around the foundation of the blackberry plants until it’s slightly muddy. Give the peel plants 1 inch of water each week if there’s no rain during the summer. Spread two to three inches of organic mulch around the base of their new shrubs. Mulching benefits blackberry bushes by reducing weed growth, slowing soil moisture evaporation and providing slow-release nutrients. Keep the mulch layer thick throughout the life of the blackberry bushes.