Blackberries are easy to grow and will provide you with lots of sweet, tasty fruits provided they are planted and cared for properly.
Best Growing Conditions...
The best and most berries will be produced when blackberry plants are growing in full sun. However, where space is limited, a blackberry cane will produce good crops even when grown in shade, which is something no other common fruit plants will do. Blackberries produce their flowers very late in the season so frost is usually not a problem.
Soil Type Preferred - Blackberries will grow reasonably well in most soil types except for very compacted clay or light chalky soil. In these soils it'll be worth your time to mix in lots of organic compost to condition the soil and add beneficial nutrients and bacteria plants need to grow healthy. Blackberries grow and produce the best fruit in well-drained but moist fertile soil that is rich in organic matter. They like the soil to hold a good supply of water, especially when the fruits are developing in summer, but not so much water that the soil stays constantly soggy or wet.
Soil pH Preferred - Backberries do best in a slightly acidic soil, somewhere between 5.5 and 7.0 on the pH scale. Whenever growing plants that prefer a specific pH it's a good idea to test the soil. Testing kits are available at most local nursery and garden centers or you can buy soil test kits online here. Your local Extension Service might provide soil testing services as well. Depending on the results of the soil test, you can add lime to raise the pH or soil sulfur to lower the pH (make more acid).
When To Fertilize...
When fertilization is necessary, it's best to feed blackberries with inorganic fertilizers, such as 10-10-10, when blooms start to appear and again after harvest. When using organic fertilizer, such as composted manure-based products, blood meal, cottonseed meal, fish emulsion or alfafa meal, fertilize in late fall before the first frost.
How To Fertilize...
FIRST YEAR
Fertilize lightly when new growth emerges in spring with 10-10-10, 13-13-13, or an organic plant food. If a soil test was done that indicated low levels of Phosphorous (middle number in fertilizer) or Potassium (third number in fertilizer) follow instructions provided on the test kit or by your Extension Service to apply sufficient amounts of these nutrients.
THEREAFTER
Blackberries require fertilizer, but only when necessary. If the leaves are healthy and dark green, and the plant is producing fruit and growing nicely, there's probably not a major need for fertilizer. If your blackberries are not growing well, and the leaves are dull or faded, fertilization and/or pH adjustment is necessary. Should you determine fertilizer is required, rake back the mulch and spread the fertilizer on top of the soil and replace the mulch.
When it comes to the type of fertilizer there are two choices:
Organic: When feeding plants that will end up on the kitchen table, I always go with organic plant foods. If you use compost, manure or another organic compost, apply it as a thin mulch around the plant in the late fall before the first frost. Blood meal, cottonseed meal, fish meal or alfalfa meal are other alternative organic fertilizers. Refer to product label for application rates when using these products. I use Dynamite Organic Plant Food to feed the few blackberry plants I have. There are many other organic plant foods on the market.
Inorganic: In early spring, just as new growth starts to appear, spread inorganic fertilizer such as 10-10-10 or 13-13-13 over the top of the soil at a rate of 10 to 12 pounds per 100 feet of row. When feeding plants individually apply 1 to 1.5 pounds per plant, beginning in the 2nd year. Feed half that amount the first year. In midsummer, or at bloom, if your blackberry bushes appear to be lackluster, you can apply an additional pound of ammonium nitrate per 100 feet or 1 ounce per plant, which will increase berry size and increase yields. Do this just before watering. Be careful when applying fertilizer not to pile it up around the canes. Instead broadcast it evenly around the plant.
