Although blackberries and raspberries are similar in some ways, there are some potential disadvantages of growing blackberries. Selecting the right variety of blackberries helps mitigate these disadvantages. Blackberries and raspberries are similar in that they grow in thickets. The berries grow on long canes. Certain varieties of both berries can benefit from trellising.
Some species of blackberries are highly invasive. According to Oregon State University, the Himalayan blackberry, also known as the Armenian blackberry, is a common invasive plant species in the Pacific Northwest. Depending on where you live, you may be required to remove any Himalayan blackberries growing on your property. They displace native plants and form impenetrable thickets of tall brambles. They are invasive because they are capable of producing 13,000 seeds per square yard. The seeds can remain viable for several years. Although the fruit is sweet and juicy, cultivating invasive varieties of blackberries like the Himalayan is not recommended.
Some noninvasive varieties of blackberries ripen late in the season. Some of these varieties, like the Navajo blackberry, fruit at the same time as other blackberries, but take longer to ripen on the brambles. Whether or not this is an issue depends on your climate. If your climate will support late ripening times, growing two different varieties, one early and one late, results in more than one crop of fruit. In some areas, late-ripening fruit become damaged by the hot summer sun, according to North Carolina State University.
Whether or not thorns are a disadvantage depends on many factors. If you have children and pets that play around your blackberry patch, thorns may be a problem. Thorns can help to keep some animals away from the thicket, thus increasing the potential yield. If thorns are a problem, select a variety without thorns. Many domesticated varieties of blackberries either have minimal thorns or are completely thornless. Thornless blackberries, because of the lower risk of cuts and pricks, are easier to harvest.