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Lisianthus

Flower
Warm season
Full sun

Also known as: Eustoma grandiflorum · Prairie Gentian

When & where

Season
Warm season — tender annual
USDA zones
Annual in all zones
Sun
Full sun
Start indoors
16–20 weeks before last frost — the slowest annual
Direct sow outdoors
Not recommended
Days to harvest
150+ days from sow to cut

Germination

Germination time
10–21 days
Soil temperature
70–75°F (21–24°C) day / 65°F night

Spacing & depth

Sow depth
Surface — needs light
Seed spacing
One pelleted seed per plug
Mature plant spacing
6–9 in (15–23 cm)
Row spacing
9 in

How to plant

Use pelleted seed on the surface of moist mix. Do not let seedlings get root-bound or 'rosette' at temps over 80°F. Bump up carefully; harden off. Prefers cool, steady growth.

Grower's tip

The florist rose look-alike. Difficult from seed but unmatched vase life (2–3 weeks). Many growers start plugs from specialists instead.

Soil preferences

Soil type

Well-drained garden soil. Native/wildflower species prefer lean soil; cutting flowers prefer richer beds.

pH range

6.0–7.0

Amendments

Work 1 in of compost into beds before sowing. Skip nitrogen fertilizer on wildflowers — it favors foliage over blooms.

Watering

Frequency

1 in per week during establishment, drought-tolerant once rooted for most species.

Method

Deep, infrequent soakings at the base. Overhead water on ornamentals promotes botrytis and rust.

Over vs. under

Overwatered: rotted crowns, mildew, floppy stems. Underwatered: small blooms, curled leaves, quick fade.

Top-water or bottom-water?

Either works — Bottom-water seed trays and young potted annuals to protect fragile stems from damping-off. Top-water established plants at the base in the morning so foliage dries by night. Avoid overhead sprinkling on open blooms.

Temperature tolerance

Ideal daytime air temp

60–80°F (16–27°C) ideal for most annuals

Ideal nighttime air temp

50–65°F (10–18°C)

Frost sensitivity

Cool-season annuals (larkspur, poppy, snapdragon) tolerate light frost; warm-season annuals (zinnia, cosmos, marigold) are frost-tender.

Container growing

Container-suitable?

Possible with the right cultivar

Recommended pot size

8–14 in (20–35 cm) wide

Notes

Compact and dwarf types do best in pots; tall cutting flowers need staking.

Succession planting

Sow cutting flowers (zinnia, cosmos, sunflower) every 3 weeks through midsummer for continuous cut stems.

Detailed harvesting

Cut in early morning when stems are turgid. For cutting varieties, harvest when the bud is just showing color and 1–2 outer petals have opened.

Post-harvest storage & preservation

Immediately re-cut stems underwater and place in clean cool water for 4 hrs before arranging. Petals can be dried on screens for potpourri or crafts.

Culinary, medicinal & other uses

Cut flowers, dried arrangements, pollinator habitat.

Medicinal or traditional uses are shared for interest only — this is not medical advice. Consult a qualified professional before using any plant medicinally.

Seed saving

Pollination

Mostly insect-pollinated (outcrossing).

Isolation needs

For pure strains, isolate 150–800 ft or bag heads. Wildflower mixes are meant to cross freely.

How to save

Stop deadheading favorite blooms; let heads dry brown and rattling on the stem, then collect into a paper bag.

Your zone's planting calendar

Pick your USDA hardiness zone and we'll estimate the key dates for lisianthus in your area. These are regional averages — always check your own last-frost forecast before sowing.

My Lisianthus notes

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