Blackberry bushes (Rubus fruticosus) are also commonly called brambles. They are hardy in U.S. Department of Agriculture plant hardiness zones 3 to 9. “Black Satin,” “Chester,” “Thornless Evergreen” and “Waldo” are thornless varieties that do well in California. Black Satin and Chester have erect stems while Thornless Evergreen and Waldo have trailing stems. Trailing types require trellising while erect types can be grown without a trellis, although they are easier to maintain and harvest when trellised.
Select a planting site that is exposed to a minimum of six to eight hours of direct sunlight each day. Allow for 2 to 4 feet of space between blackberry bushes with 8 to 10 feet between rows. Orient the rows to run north and south. Prepare the site at least three months prior to planting. Remove any preexisting vegetation and check the soil pH to make sure it is between 5.5 and 6.5.
Spread a 3- to 6-inch deep layer or 1 lb. per square foot of organic matter such as well-aged compost and leaf mold over the planting site. Add lime to raise the soil pH level or sulfur to lower it. Till the soil amendments into the soil to a depth of 10 to 12 inches. Use a shovel or rake to pull the soil from between the rows into raised beds or planting rows that are 8 to 10 inches high, 2 feet wide along the top and 4 feet wide at the base.
Plant the blackberry bushes in late fall or winter at the same depth they were growing previously. Use sharp hand pruners to remove damaged roots before planting. Loosen the roots and spread them out in the planting hole. Push the back-fill dirt into the hole by hand. Make sure it fills in below and between the roots. Water the bushes generously. Add more back-fill soil if the soil settles around the bush. Trim each cane or stem back to a height of 6 inches. Spread a 3- to 4-inch deep 4-foot wide layer of organic mulch around the bushes.
Set one 4- by 4-inch 8-foot long post 2 feet deep in the ground at either end of each row. Set 2- by 2-inch 8-foot long posts 2 feet deep and 20 to 30 feet apart within each row. Run two strands of 9-gauge wire along the posts, one 3 1/2 feet from the ground and the other 5 feet from the ground, to make a two-wire trellis. Use a hammer and U-nails to secure the wires to the posts.
Water the blackberry bushes as often as necessary to keep the soil uniformly moist. Give them 1 to 2 inches of water each week from mid-spring to mid-autumn. Apply 50 lbs. of organic fertilizer such as well-aged manure or compost per 100-foot row in late fall or early winter or 5 to 6 lbs. of 20-20-20 inorganic fertilizer per 100-foot row in early spring. Water the bushes thoroughly after applying fertilizer.
Attach the canes to the trellis wires as they grow. Prune off the fruiting canes or floricanes at the base of the bush in mid-winter after they produce fruit. Prune off all but three or four of the sturdiest new canes or primocanes on erect blackberry varieties and all but six to 12 primocanes on trailing varieties in mid-winter.
Things You Will Need
- Soil pH test kit
- Organic matter
- Lime or sulfur
- Sharp hand pruners
- Organic mulch
- 4- by 4-inch 8-foot long posts
- 2- by 2-inch 8-foot long posts
- 9-gauge wire
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