Great burnet, Sanguisorba officinalis Seeds

Great burnet (Sanguisorba officinalis) is a clump-forming perennial, 1–1.5 m tall, with dense maroon flower spikes from summer into early autumn. Its seed needs no cold stratification, according to the one study we have on file.

Also known as: Grande pimprenelle (French), Großer Wiesenknopf (German), Pimpinela mayor (Spanish), Salvastrella maggiore (Italian), Krovokhlyobka, Di yu (Chinese), Waremokō (Japanese), Poterium officinale (synonym).

Does it need chilling before sowing?

Probably not. A Native Plants Journal study of burnet species including S. officinalis found germination needed no special pretreatment, and 1 week to 5 months of cold at 4 °C followed by 21 °C in light did not improve it. This is one study on one seed lot, so treat it as approximate.

Sowing and growing

• Sow in pots in a cold frame in spring or autumn (Royal Horticultural Society advice).
• Plant out in full sun or partial shade, in moist but well-drained soil of almost any type.
• Established plants are hardy below −20 °C.

Where it fits and what to watch

The plant spreads by rhizomes, so site it where a widening clump is welcome. In the wild it favours floodplain meadows, which hints at its liking for moisture; the flower heads are crimson to maroon and open from June to September.

We have no tested germination percentage or emergence time for this lot and do not state one.

FAQ

Should I put the seed in the fridge first?

The available study found no gain from chilling, so it is not required. Sowing in a cold frame still follows standard practice.

How tall does it get?

1–1.5 m according to the Royal Horticultural Society; wildlife-trust sources give up to 1.2 m.

Will it take over the bed?

It is rhizomatous and can spread readily, so leave room or divide it in spring or autumn.