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Tithonia

Flower
Warm season annual
Full sun

Also known as: Mexican sunflower · Tithonia rotundifolia

Varieties

4 types of tithonia

When & where

Season
Warm season annual
USDA zones
Annual in zones 2–11; loves heat and humidity
Sun
Full sun
Start indoors
4–6 weeks before last frost
Direct sow outdoors
After last frost, soil ≥ 70°F
Days to harvest
75–95 days to bloom

Germination

Germination time
7–14 days
Soil temperature
70–80°F (21–27°C)

Spacing & depth

Sow depth
1/4" (6 mm)
Seed spacing
6 in, thin to 24–36 in
Mature plant spacing
24–36 in (60–90 cm)
Row spacing
36 in (90 cm)

How to plant

Direct-sow or start in deep cells to avoid transplant shock. Plants become 5–8 ft bushes covered in 3 in vermilion-orange daisy blooms. Stake in windy spots. Sear cut stems in boiling water 7 seconds for vase life.

Grower's tip

One of the top monarch butterfly nectar plants. Blooms nonstop from midsummer to frost. Deadhead to keep flowering.

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 at the base in the morning. Overhead water batters open flowers and spreads botrytis on tightly-packed 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, 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 tithonia in your area. These are regional averages — always check your own last-frost forecast before sowing.

From your kitchen — grow tithonia 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.

My Tithonia notes

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