Zinnia · Shahrīār, Tehran, Iran

When to sow zinnias in Shahrīār

Main outdoor window

25 Mar - 8 Apr

The window this page is built around.

Timed from last spring frost

18 March

In Shahrīār, on your chosen risk.

Ready to pick

24 May - 13 Jun

If you plant at the start of the window.

The average last frost. Half of all years are later than this.

Cautious Balanced Bold

Step by step in Shahrīār

Each window is a range, not a single day. Earlier in the range buys you a longer season; later in it buys you a safer one.

Start indoors

18 Feb - 4 Mar

Four weeks before your last frost, under cover or on a windowsill.

Sow direct

25 Mar - 8 Apr

One week after your last frost.

Plant out

25 Mar - 8 Apr

One week after your last frost.

In flower

24 May - 13 Jun

Sow in succession. A single sowing gives you a single glut. Sow a short row every 21 days through the window above and you get a steady supply instead.

Frost tolerance

Tender

Damaged below

0°C (32°F)

Days to flowering

60–80

Min soil temp

21°C (69.8°F)

Spacing

25 cm

Sowing depth

6 mm (0.2 in)

Sun

Full

Zinnias through the year

Against the frost risk in Shahrīār

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Zinnias

Frost risk Start indoors Sow direct Plant out Harvest Today

Why these dates

Direct sowing after last frost usually beats transplanting - zinnias dislike root disturbance and catch up quickly.

Killed by the first frost at either end of the season. Strictly a warm-season flower.

Seed packets and extension guides express timing as weeks either side of the last spring frost, because that is the only reference point that travels. Zinnias are timed from 4 weeks before that frost for an indoor start, with planting out 1 weeks after it, and this page simply resolves those offsets against the frost date computed for Shahrīār.

The median frost-free season here is 260 days, against 60 to 80 days to first flower for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.

See every crop timed for Shahrīār →

Nearby

Zinnias in places close by

Qods 8 km Golestān 19 km Eslamshahr 20 km Karaj 20 km Tehran 33 km Qarchak 54 km

Also in Shahrīār

Other flowers to time

Tulips very hardy Daffodils very hardy Dahlias tender Sunflowers tender Crocuses very hardy Peonies very hardy Calendulas hardy Hyacinths very hardy Sweet peas hardy Pansies very hardy Snowdrops very hardy

Growing zinnias in Shahrīār

When should I plant zinnias in Shahrīār?

Aim for 25 Mar - 8 Apr in an average year. If you would rather not gamble on the weather, wait until 11-25 Apr - by then frost has finished in nine years out of ten.

When will zinnias be ready to harvest in Shahrīār?

Expect to start picking around 24 May - 13 Jun, based on 60 to 80 days to maturity from the planting date calculated for this location.

How much frost will zinnias tolerate?

Killed by the first frost at either end of the season. Strictly a warm-season flower.