Also known as Dewberry, our native blackberry grows well in nearly all enivronments on the west side of the Cascade Mountains. They send out long thin vines that will sometimes take root in places distant from the parent plant. They do not grow upright more than two or three feet due to the thin vines. However, if they have other brush to grow over, the vines can reach heights of six feet, though they will usually drape over branches and reach back to the ground. Individual vines can grow more than ten feet long in a single season and are typically sent off in all directions. If a vine is growing where you do not want it, you can gently pick it up and move it to a more desirable spot. Note, however, that the vines are very thin and you can easily kink them if you try to move them. For best results, move the vines before they get too long.
Because the vines do not twine around other plants, they simply drape over them. In the absence of other plants, the trailing blackberry can form a tangled mass that can serve as a ground cover. The berries are smaller and less sweet than the invasive Himalayan Blackberry, but they have a unique flavor that some people prefer. However it can be hard on one's back to pick them all from ground level. You may wish to grow them on a trellis so the berries are easy to access. Cyclone fences can serve as a trellis which also will provide a bit of privacy as well. But training the vines on a trellis requires constant attention until the vines have reached the top of the trellis. You can also grow them in containers on a deck and allow the vines to hang down over the edge like a living curtain.
Trailing blackberry has smaller thorns even on very long vines, but they can still scratch. You may wish to wear gardening gloves when handling them. However they are nowhere as painful to deal with as the invasive blackberries. Though the vines can establish roots for new plants in soil, they do so far less often than the invasive blackberries. However, by making sure the vines are kept out of areas where you don't want them, you can avoid having them sprout new plants where you don't want them.
Though Trailing blackberry thrives on neglect, you can increase the size and quality of the fruit by making sure the plants get 1-2" of water every week while berries are ripening. Just make sure to water where they plant is rooted - watering a vine that is 8' away from the roots will do nothing for the plant. The roots are shallow but need soil with good drainage. They like our naturally acidic soils, so avoid using soil amendments that reduce soil acidity. Though they grow in shade, they also like full sun and are more likely to produce fruit if they get six or more hours of sunlight during the day.
The plants are self-fertile. In areas with milder winters they are evergreen. The berries are not as large, nor as numerous, as invasive blackberry. They do not hybridize with invasive Asian blackberry. They can live with neglect and will grow in poor soil with relatively little water, but will grow slowly and produce little or no berries under those conditions. In containers, they will need regularly watering.
It may be difficult to tell if a newly sprouted blackberry is a native plant or an invasive blackberry. You may need to let it grow for a month or so before you can tell them apart. Here are some guidelines for telling the difference between the native and invasive blackberries.
| Native | Invasive |
|---|---|
| Flowers always white, never pink | Flowers can be pink or white |
| Flower petals are more oblong (usually more than twice as long as wide) | Flower petals more rounded |
| Vines are never more than 1/4" thick. | Older vines can be much more than 1/4" thick. |
| Vines are green or bluish, but never have red. | Vines are green or redish, but never have blue. |
| Vines are always circular in cross-section. | Vines have multiple sides, corners, and/or ridges. They are star-shaped or polygonal in cross-section. |
| One crop in mid-summer. | Produce berries into October or first frost. |