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Cornflower variety
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Blue Boy

Flower
70 days to harvest
Full sun

What's special about Blue Boy

The classic true-blue cornflower — 3 ft tall with 1.5 in double button blooms. Old-fashioned favorite.

Growing this variety

Blue Boy follows the same growing basics as Cornflower. Variety-specific maturity above; everything else below applies to the whole Cornflower family.

Season
Cool season annual
USDA zones
Annual in zones 2–11
Sun
Full sun
Start indoors
4 weeks before last frost
Direct sow outdoors
2–4 weeks before last frost (frost-tolerant)
Days to harvest
70 days

Germination

Germination time
7–14 days
Soil temperature
60–65°F (15–18°C)

Spacing & depth

Sow depth
1/2" (12 mm) — needs darkness
Seed spacing
3–4 in (8–10 cm), thin to 6–12 in
Mature plant spacing
6–12 in (15–30 cm)
Row spacing
18 in (45 cm)

How to plant

Cover well — cornflower seed needs darkness to germinate. Direct sow in cool soil for best results.

Grower's tip

Attracts beneficial insects that eat aphids.

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?

Prefers top-watering — Top-water (overhead or rain) — grains are wind-pollinated and tolerate wet foliage. Water deeply and infrequently.

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, edible garnishes (borage, nasturtium, calendula, viola).

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 cornflower in your area. These are regional averages — always check your own last-frost forecast before sowing.

My Blue Boy Cornflower notes

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Blue Boy Cornflower seeds on hand

Track packets and loose seeds you already have. Private to your account.

Par level — leave at 0 for no alert. Anything below par shows on Seed Starting and your shopping list.

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From your kitchen — grow cornflower from what you already have

Deadhead less. Let the best blooms fade and set seed on the plant — that's your next year's packet.

  1. 1Mark 2–3 of your favorite flowers with a bit of yarn and stop deadheading them.
  2. 2Wait until the seed head or pod dries fully on the plant — brown, papery, and rattling.
  3. 3Cut whole heads into a paper bag on a dry day; shake or rub to free seed.
  4. 4Sieve out chaff and store cool and dry in a labeled envelope.

Storage: 2–5 years for most flower seed.

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