Planting blackberries in a raised bed this autumn: why one plant can already be too many

Frau Schneider ordered three thornless blackberry plants last week, no thorns on purpose because of the kids, planning to put all three into her raised bed. When the package arrived, she showed me the planting instructions: two metres of spacing per plant. Her raised bed is 120 by 80 centimetres. One plant barely fits in there, let alone three.

Why now is actually the right moment

The timing itself is correct: blackberries go in between calendar week 40 and 43, which is right now. The soil is still warm enough for roots to establish before the first frost, so the plant doesn't have to grow new roots and new canes at the same time next spring. Plant in October and you get a small first harvest next summer. Wait until spring and you lose an entire year.

The space problem isn't fine print

150 centimetres of spacing for a regular blackberry, 200 for the thornless variety – that's not the grower being overcautious, it's just what the plant does. In its second year, a blackberry sends out long, arching canes that need a trellis and will crowd each other out if planted too close. Once the air stops moving between the leaves, that's exactly where powdery mildew sets in. A standard-sized raised bed has room for one plant, along the back wall, with a trellis behind it. Not three.

The roots don't stay where you put them

What most people don't realise: blackberry roots run deep and drift sideways over time, including straight under the raised bed's wall if the bed sits directly on soil rather than on pavers or pond liner. After two or three years, a new shoot suddenly turns up in the middle of the lawn, a metre from where you actually planted it. That's not a mistake, it's just what the plant does. If you don't want that, dig in a root barrier of sturdy liner along the bed wall at planting time, at least 40 centimetres deep. If you're relaxed about it, just cut down any new shoots in the lawn every year.

What I told Frau Schneider

Keep one plant, give the other two away or send them back. Stick with the thornless variety despite the bigger footprint, since the kids mattered more to her than the extra space. Don't plant it next to raspberries, the two tend to pick up the same fungal diseases. Chives or oregano at the base, though, help keep aphids away and barely take up any room themselves.

Frau Schneider settled on the back corner, right in front of an old fence panel that now doubles as a trellis. The other two plants went to her sister, who has an actual garden instead of a raised bed. Both of them get their first handful of blackberries next summer, just not all in the same bed.

🦔 Stachi