Jacob’s ladder
Polemonium
An ornamental plant, planted March or September to November, or sown March or May.
In September: mulch the Jacob’s ladder and cut it back. It can be planted now.
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Jacob’s ladder, month by month
Bar: the usual months. Sprout: this month.
| Sowing, planting or job | Sep | Oct | Nov | Dec | 2027Jan | Feb | Mar | Apr | May | Jun | Jul | Aug |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sow under cover. | none | none | none | none | none | none | usual | none | none | none | none | none |
| Sow outdoors. | none | none | none | none | none | none | none | none | usual | none | none | none |
| Plant a pot-grown Jacob’s ladder. | usual | usual | usual | none | none | none | usual | none | none | none | none | none |
| Lift and divide the Jacob’s ladder. | none | none | none | none | none | none | usual | usual | usual | none | none | none |
| Mulch the Jacob’s ladder. | usual | usual | usual | none | none | none | usual | usual | usual | none | none | none |
| Cut the Jacob’s ladder back hard after flowering. | none | none | none | none | none | none | none | none | none | usual | usual | none |
| Cut back the Jacob’s ladder. | usual | usual | usual | none | none | none | none | none | none | none | none | none |
What to do, and when
The usual months for a UK garden. Your own plan gives the week.
Sowing and planting
Sow under cover in March, on the surface. Moderate source: Gardeners’ World. Weaker source for the depth: Floral Encounters.
Sow outdoors in May, 0.15cm deep, 30cm apart. Moderate sources: Sheffield’s Seed Company and Jekka’s.
Plant a pot-grown Jacob’s ladder March, and September to November, 30 to 40cm apart. Moderate sources: Gardeners’ World and Mr Fothergill’s.
Lift and divide the Jacob’s ladder
Usually March to May. Strong source: RHS.
Mulch the Jacob’s ladder
Spread a generous layer of well-rotted organic matter around the base. From Hayloft Plants.
Usually March to May, and September to November. Moderate source: Gardeners’ World.
Cut the Jacob’s ladder back hard after flowering
Gardeners call this the Hampton hack.
Almost to the ground, straight after its first flowers. Fresh leaves follow, and often a second flush of flowers.
Usually June to July. Moderate source: RHS.
Cut back the Jacob’s ladder
Cut the whole plant down to ground level.
Usually September to November. Moderate source: Gardeners’ World.
What the source words mean
Strong: the RHS page for this plant is among them.Moderate: another trusted UK source, or the RHS on its group.Weaker: a blog, a forum, a small website or a page from outside the UK. Treat it as a guide.
Every line above names the page it comes from. Where we found no good source for a job, we left it out. Where the name “Jacob’s ladder” comes from.