key growing information

Growing Zinnias from Seed

How to grow zinnias from seed: warm germination, transplants without root disturbance, direct sowing, succession, pinching and deadheading, frost and cold sensitivity, cutting stage, soil and uses.
By Hensley’s Seed Co.

Zinnia - Key Growing Information

A row of several zinnia varieties in recent trials, from which we selected the top-performing cultivars.

DAYS TO GERMINATION:

Seedlings appear in just 3–5 days at 80–85°F (27–29°C).

SOWING:

Transplants are recommended: sow into 72-cell flats or your usual containers 4 weeks before planting out, and cover the seed. A heat mat helps hold the right temperature; at 70–75°F (21–24°C), germination slows to 5–7 days. Don't let plants get rootbound, and avoid disturbing the roots, since transplant shock or other stress can make double types bloom single for a while. To sow in place, plant ¼" deep. Sow or plant every 2 weeks for a long run of quality stems. Pinch out the first bud or bloom and keep deadheading to encourage strong branching and more flowers. Zinnias are very frost-tender.

LIGHT PREFERENCE:

Full sun.

PLANT HEIGHT:

Depends on the variety; no support needed.

PLANT SPACING:

Space plants 9–12" apart.

HARDINESS ZONES:

Grown as an annual.

VASE LIFE:

About 7–10 days.

STORAGE TEMPERATURE:

Store cut stems at 40–50°F (4–10°C); zinnias are easily damaged by cold.

HARVEST:

Cut before flowers are fully open, when the stem is firm from the cut right up to just under the bloom.

SOIL REQUIREMENTS:

Fertile soil rich in organic matter, ideally pH 6.3–6.8.

USES:

Taller types make superb cut flowers; also good in beds, borders and mass plantings.
SCIENTIFIC NAME: Zinnia spp.

Source and attribution

Migrated library resource. Original named people, organizations, research, and factual provenance are retained.