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True Blue
hybrid border gentian · Darrell Probst, 2009, USA
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)
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.
References
- US Plant Patent – Gentiana ‘True Blue’ (PP20433)
- RHS – Gentiana ‘True Blue’ entry
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