Product Field NotesCompanion Plants
Leadwort: Gentian-Blue Flowers After the Lavender Harvest
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Leadwort, also called hardy plumbago, is a low groundcover that saves its best work for the end of the year. Starting in mid-August, clusters of intense gentian-blue flowers open at the tips of wiry reddish stems and keep coming until a hard frost. As the nights cool, the leaves turn bronzy red to burgundy, and the blue flowers glow against them.
For lavender growers, that timing is the whole point. By the time leadwort hits its stride, the lavender has been harvested or sheared, and the bed would otherwise be all silver and green.
Leadwort at a glance
| Trait | What to expect |
|---|---|
| Botanical name | Ceratostigma plumbaginoides |
| Flowers | Gentian blue, about three-quarters of an inch across |
| Foliage | Green in summer, bronzy red to burgundy in fall |
| Size | 8 to 12 inches tall, 10 to 20 inches wide |
| Bloom | Mid-August until hard frost, peaking mid-September |
| Hardiness | USDA zones 5 to 9 |
| Light | Full sun to part shade |
| Extras | Deer resistant; RHS Award of Garden Merit |
Why it suits a lavender bed
Leadwort and lavender agree on the basics: sun and good drainage. That makes leadwort one of the few groundcovers you can run right along the front of a lavender planting without making the lavender's crowns wet. Keep a small gap so the lavender still gets air around its base, and let the leadwort knit together as a low edging in front.
The color story is just as good. Blue flowers and red-bronze leaves look fresh in September, when most of the summer garden is tired. If you want to plan the whole season, the Companion Plant Planner shows how early, midsummer and late bloomers stack up.
Planting and care
- Soil: average, well-drained ground. Poor soil is fine; wet, heavy soil invites root rot.
- Timing: plant before midsummer so it can settle in before its first winter.
- Water: regularly while it establishes, then only in long dry spells.
- Heat: it handles summer heat well; in the hottest sites a little afternoon shade keeps the leaves fresher.
- Spring: cut old stems to the ground in early spring.
Do not panic in May
Leadwort is one of the last perennials to wake up in spring. It is easy to assume it died over winter and plant something on top of it, so mark its spot in fall. That late start is also an opportunity: tuck small spring bulbs among it, and they will bloom and fade before the leadwort covers their tired foliage. In zone 5 gardens, a light winter mulch helps in exposed sites, kept clear of nearby lavender crowns.
How it spreads
It spreads slowly by rhizomes into a mat, which makes it useful on slopes, in rock gardens and under shrubs. It is a groundcover, not a thug, but it will fill gaps over a few seasons, so give it room or edge it where you want it to stop.
Frequently asked questions
Is leadwort good for cut flowers?
Not really. The flowers are small and short-stemmed. Enjoy them in the garden, where bees and other pollinators visit them late in the season.
Does it have a scent?
No notable fragrance. Let the lavender handle that job.
How is it sold?
As a full 72-cell plug tray, which suits growers and anyone edging long beds or covering a slope. See the product page for current availability and the Wholesale Hub for other trays.
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