Gentiana 'True Blue'
A modern hybrid selected for sturdy, upright stems and a long flowering window. Large tubular flowers open along the stems from midsummer into early fall. Plants grow reliably in ordinary garden soils with sufficient moisture and full sun to part shade. This cultivar is hardy in a wide cold‑climate range and is less finicky than alpine species.
At‑a‑glance
- Group/Class: hybrid border gentian
- Height × spread: 18-30 in (45-76 cm) × 18 in (45 cm)
- Bloom window: mid July to mid September
- Color & flower form: rich true blue, tubular, open flowers up the stems
- Fragrance: 0 none
- USDA hardiness: zones 4-8
- Breeder / Year / Origin: Darrell Probst, 2009, USA
- Awards/registration: US Plant Patent PP20433
- Cut‑flower notes: Patent notes average of about 14 days as a cut flower under test conditions; stems sturdy.
- Pet safety: unknown
How it differs
- Open flowers along the stems rather than closed bottle blooms.
- Long bloom period in ordinary garden soils.
- Upright, well‑branched habit that suits borders.
- Broader hardiness range than many species gentians.
Strengths
- True blue flowers in midsummer to early fall.
- Good stem strength for gardens and cutting.
- Tolerates average soils with steady moisture.
Care in one minute
- Grow in full sun to part shade with evenly moist, well‑drained soil.
- Water in dry periods; do not allow to wilt at bud stage.
- Apply a light spring feed; avoid heavy nitrogen.
- Cut back spent stems after flowering to tidy.
- Mulch lightly to conserve moisture while keeping crowns free.
Watch‑outs
- Requires consistent moisture for best flowering.
- High heat with drought reduces display.
- Avoid very alkaline soils if performance flags.
Best uses (tags)
borders, cutting, pollinators, containers, late season
Provenance note
Bred by Darrell R. Probst in Massachusetts from a cross involving a hybrid of Gentiana makinoi and a plant likely allied to Gentiana scabra; patented in 2009 as PP20433.
Written by: Your Flowers Guide editorial team
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