Illustration
Photo credits and licenses
Real photographs from naturalists and photographers worldwide, each used under its own license. Credit: Photo by Rose Zappa / iNaturalist (CC BY), Photo by Rose Zappa / iNaturalist (CC BY), Photo by Andrew St. Paul / iNaturalist (CC BY) and Photo by Andrew St. Paul / iNaturalist (CC BY). How photos are sourced →
Jacob's Ladder
Polemonium
Also called greek valerian
Also comes in white.
Jacob's Ladder blooms from May through June.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Jacob's Ladder
Plant it in part shade. It prefers moderate water. It is hardy in USDA zones 3–7. Expect it to reach about 20 in tall and 16 in wide at maturity, in roughly 2 years (not yet checked).
What was checked
Mature height and spread, hardiness zones, sun and the trait tags were checked against named botanical sources for this plant. The bloom months and water need on this page were not, and each fact above says which. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.
When to plant Jacob's Ladder
Plant Jacob's Ladder in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. In zone 5, the middle of its hardy zones 3 to 7, spring means April to June and fall means August or September. Once settled, it blooms from May to June.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 5, the middle of this plant's hardy range, start with zone 5 in April. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Jacob's Ladder get?
20 intall5 ft 7 inan adult16 inwideSee Jacob's Ladder in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant Jacob's Ladder
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Space Jacob's Ladder about 16 in apart, center to center, so each plant has room to reach its full width.
Add Jacob's Ladder to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Where these facts come from
Jacob's Ladder's height, spread, hardiness zones, sun and trait tags were checked against 21 published sources on July 31, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.
- The Morton ArboretumPolemonium reptansheight, spread, hardiness zones, sun, years to mature size and trait tags
- Missouri Botanical GardenPlant Finder - Polemonium 'Heaven Scent'height, spread, hardiness zones, sun and trait tags
- Missouri Botanical GardenPlant Finder - Polemonium 'Lace Towers'height, spread, hardiness zones, sun and trait tags
- Missouri Botanical GardenPlant Finder - Polemonium caeruleum 'Snow and Sapphires'height, spread, hardiness zones, sun and trait tags
- NC State ExtensionPlant Toolbox - Polemonium reptansheight, spread, hardiness zones, sun and trait tags
- New Moon NurseryPolemonium reptansheight, spread, hardiness zones, sun and trait tags
- Missouri Botanical GardenPlant Finder - Polemonium caeruleumheight, spread, hardiness zones and sun
- Missouri Botanical GardenPlant Finder - Polemonium reptansheight, spread, hardiness zones and sun
- Missouri Botanical GardenPlant Finder - Polemonium reptans 'Stairway to Heaven'height, spread, hardiness zones and sun
- Missouri Botanical GardenPlant Finder - Polemonium 'Bressingham Purple'height, spread, hardiness zones and sun
- Missouri Botanical GardenPlant Finder - Polemonium caeruleum 'Blanjou' BRISE D'ANJOUheight, spread, hardiness zones and sun
- Missouri Botanical GardenPlant Finder - Polemonium yezoense 'Kaleidoscope'height, spread, hardiness zones and sun
- Mt. Cuba CenterPolemonium reptansheight, hardiness zones, sun and trait tags
- RHSPolemonium caeruleumheight, spread, sun and years to mature size
- RHSPolemonium reptansheight, spread, sun and years to mature size
- University of Illinois ExtensionHort Answers - Polemonium reptansheight, hardiness zones, sun and trait tags
- Lady Bird Johnson Wildflower CenterPolemonium reptansheight, sun and trait tags
- Missouri Department of ConservationField Guide - Polemonium reptansheight, sun and trait tags
- Prairie Moon NurseryPolemonium reptansheight, hardiness zones and sun
- Native Plant Trust (Go Botany)Go Botany, Native Plant Trust - Polemonium reptansheight
- Native Plant Trust (Go Botany)Go Botany, Native Plant Trust - Polemonium caeruleumheight
How the checking works, and what each standard covers, is on the verified plants page.
Good to know about Jacob's Ladder
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note. A note reports what its source says; where that differs from a fact above, the fact above is this entry's stored value, and its mark says whether it has been checked.
Worth knowing
No extension source rates it toxic, and the 'Jacob's Ladder' entry in pet-poison databases is actually an unrelated plant, Smilax, not this one. per NC State and USDA
Two plants, one name
'Jacob's Ladder' covers two plants: North American native Polemonium reptans and the Eurasian garden species P. caeruleum. For native or pollinator value, choose reptans. per NC State and Missouri Botanical Garden
Dislikes heat and humidity
It fails in hot, humid summers; heat plus dry soil scorches the leaves and can force it into summer dormancy. A cool-climate woodlander. per NC State
Early food for native bees
Its spring flowers feed emerging native bees and bumblebees early in the season, when little else is blooming; butterflies visit too. per NC State and Wildflower Center
Deer resistant
Deer usually leave it alone; three sources rate it deer resistant, though very hungry deer may still nibble. per NC State
Grown for their foliage
Some varieties are grown for their leaves, not flowers: 'Stairway to Heaven' has cream-and-green variegated foliage; 'Heaven Scent' emerges reddish. per Chicago Botanic Garden
What pairs well with Jacob's Ladder
Good companions share its growing conditions and add something it lacks: an earlier or later bloom, a lower carpet in front, or structure through winter.
Hellebore
Shares part shade and moderate water; blooms in late winter, before this one opens; both offer pollinator forage, in different months; evergreen, so the bed keeps its shape through winter.
Summersweet
Shares part shade and moderate to high water; blooms in midsummer as this one finishes; both are strong pollinator plants, and they feed in different months; taller at 6 ft, for the layer behind it.
Azalea
Shares part shade and moderate water; opens in mid spring and overlaps into this one's season; both are strong pollinator plants; evergreen, so the bed keeps its shape through winter.
Cardinal Flower
Takes part sun to part shade and moderate to high water; blooms in midsummer as this one finishes; both are strong pollinator plants, and they feed in different months; taller at 3.5 ft, for the layer behind it.
Ligularia
Shares part shade and moderate to high water; blooms in midsummer as this one finishes; both are strong pollinator plants, and they feed in different months; taller at 4 ft, for the layer behind it.
Northern Sea Oats
Shares part shade and moderate water; blooms in midsummer as this one finishes; its seed heads stand through winter, for structure and the birds; taller at 3.5 ft, for the layer behind it.
Eastern Redbud
Takes part sun to part shade and moderate water; blooms in mid spring, before this one opens; both are strong pollinator plants, and they feed in different months.
Windflower
Takes part sun to part shade and moderate water; blooms in early spring, before this one opens; both are strong pollinator plants, and they feed in different months; lower at 6 in, for the front of the border.
Featured in these guides
Explore similar plants
You might also like
Design a garden with this
Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.