Sweet alyssum · Chengdu, Sichuan, China
When to plant sweet alyssum in Chengdu
Main outdoor window
16 Feb - 16 Mar
A climate estimate. Check your soil, forecast and cultivar.
Timed from last spring frost
14 February
In Chengdu, on your chosen risk.
First flowers
7-22 Apr
If you plant at the start of the window.
The average last frost. Half of all years are later than this.
Step by step in Chengdu
Download these planting dates (.ics)
Import into Apple Calendar, Google Calendar or Outlook. Dates use the selected risk level and are planning estimates, not frost alerts.
Each window is a planning range. Check the forecast, soil and cultivar before planting; a later date is not automatically safer in hot or wet conditions.
Start indoors
19 Dec - 17 Jan
Eight weeks before your last frost, under cover or on a windowsill.
Sow direct
16 Feb - 16 Mar
Delayed by a soil-warming estimate derived from historical air temperatures. The frost-only date would be 7 Feb. Measure your soil before planting.
Plant out
16 Feb - 16 Mar
Delayed by a soil-warming estimate derived from historical air temperatures. The frost-only date would be 7 Feb. Measure your soil before planting.
In flower
7-22 Apr
Sweet alyssum through the year
Against the frost risk in Chengdu
Seasonal context
Rainfall and the growing season in Chengdu
July has the highest average precipitation (224 mm); December has the lowest (12 mm). Compare this pattern with the planting windows and your water supply.
During wetter months, check that beds and containers drain after heavy rain. During drier months, plan how you will keep seeds and new transplants watered. Monthly averages can hide long dry spells and intense storms; they do not show soil moisture, humidity or this week's weather.
Source: NASA POWER, corrected MERRA-2 precipitation, 2001–2020. Values are approximate monthly totals, including the water equivalent of snow, from the nearest 0.5° × 0.625° grid cell. This reference period differs from the temperature record. Rainfall provides context and does not change the calculated planting dates. Method and limitations.
Monthly growing conditions in Chengdu
Compare the planting window with the local temperature pattern. These are historical monthly averages, not this year's forecast or measured soil temperatures. Average frost days do not tell you whether a particular night will freeze.
| Month | Average low | Average high | Frost days |
|---|---|---|---|
| January | 0.8°C (33.4°F)33.4°F (0.8°C) | 11.6°C (52.8°F)52.8°F (11.6°C) | 12.1 |
| February | 3.1°C (37.6°F)37.6°F (3.1°C) | 14.8°C (58.6°F)58.6°F (14.8°C) | 3.7 |
| March | 8.1°C (46.5°F)46.5°F (8.1°C) | 20.4°C (68.8°F)68.8°F (20.4°C) | 0.1 |
| April | 13.2°C (55.8°F)55.8°F (13.2°C) | 26°C (78.8°F)78.8°F (26°C) | 0.0 |
| May | 17.5°C (63.5°F)63.5°F (17.5°C) | 29.8°C (85.7°F)85.7°F (29.8°C) | 0.0 |
| June | 21°C (69.7°F)69.7°F (21°C) | 32.4°C (90.4°F)90.4°F (32.4°C) | 0.0 |
| July | 23.2°C (73.7°F)73.7°F (23.2°C) | 32.7°C (90.8°F)90.8°F (32.7°C) | 0.0 |
| August | 22.5°C (72.6°F)72.6°F (22.5°C) | 31.5°C (88.6°F)88.6°F (31.5°C) | 0.0 |
| September | 18.8°C (65.8°F)65.8°F (18.8°C) | 27.9°C (82.3°F)82.3°F (27.9°C) | 0.0 |
| October | 13.7°C (56.7°F)56.7°F (13.7°C) | 23°C (73.4°F)73.4°F (23°C) | 0.0 |
| November | 8°C (46.4°F)46.4°F (8°C) | 18°C (64.4°F)64.4°F (18°C) | 0.3 |
| December | 2.2°C (36°F)36°F (2.2°C) | 12.5°C (54.5°F)54.5°F (12.5°C) | 6.1 |
For sweet alyssum, also check drainage, sunlight and cultivar requirements. See the rainfall context above; humidity, irrigation and local pest pressure are not calculated.
Local growing check
Before choosing sweet alyssum for Chengdu
- July is the wettest month in the rainfall grid, averaging about 224 mm. Check how your own bed drains and plan watering around actual soil moisture; monthly rain totals are not an irrigation schedule.
The temperature and rainfall tables on this page show the underlying climate estimates. How these suitability checks work · Record what happens in your garden.
Before you plant sweet alyssum
Use the calendar to plan ahead, then check the conditions in your own garden.
- Measure the soil at sowing depth. Aim for at least 10°C (50°F); the calendar estimates soil warmth from air temperatures and cannot measure your bed.
- Frost tolerance does not make saturated or frozen soil suitable for planting. Wait until the bed can be worked without smearing or compacting it.
- Harden off plants raised indoors: gradually expose them to outdoor light, wind and temperature before their final move into the bed.
- Use the maturity range on your seed packet when choosing a variety. Cold, short days and transplant stress can make harvest later than the calendar estimate.
Use alyssum as a low flowering edge and renew tired growth
Provide a drained position with suitable sun, using some shade where intense summer heat shortens flowering. Establishment moisture matters even though older plants can tolerate some drying.
Trim tired growth when appropriate to encourage a fresh flush, and decide whether self-sown seedlings fit the planting plan. Check drainage if plants collapse at the base. Record the cooler-season display separately from summer decline.
What to record this season
Did light trimming renew flowers, and which season gave the longest low-growing display? Add the cultivar, sowing date and conditions to your growing record so you can compare next season.
Further reading: NC State Extension: Lobularia maritima . General crop guidance; local dates on this site are calculated separately. Source checked 19 September 2026 by Safe to Plant; this is not an expert review.
The reference describes plant identity and cultivation. Its regional calendar months and hardiness observations do not validate the calculated dates for another location.
How the dates are calculated and their limits · Keep a growing record · Report a local discrepancy
Why these dates
Provide a drained position with suitable sun, using some shade where intense summer heat shortens flowering. Establishment moisture matters even though older plants can tolerate some drying.
Check the named variety and local forecast before exposing young growth. The catalog cold-damage figure is a reference, not a guarantee: plant age, acclimatisation, wind and the duration of a freeze affect damage.
This calendar uses frost-relative offsets as a starting point. Sweet alyssum are timed from 8 weeks before that frost for an indoor start, with planting out 1 weeks before it, and this page simply resolves those offsets against the frost date computed for Chengdu.
The calendar also applies a soil-warming estimate derived from historical air temperatures. Where that estimate is later than the frost-based date, it delays the window. Soil in your own garden can warm earlier or later; a thermometer at sowing depth is a better final check. Cold, wet conditions can slow germination and increase decay risk.
Chengdu is zone 9b, within the crop's general range. This is an initial cold-hardiness check; cultivar, exposure, drainage and unusual winters can still change the outcome.
The median frost-free season here is 300 days, against 50 to 65 days to first flower for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Also in Chengdu
Other flowers to time
Growing sweet alyssum in Chengdu
Can I grow sweet alyssum in Chengdu?
The calendar estimates a planting window, not a guarantee of success. July is the wettest month in the rainfall grid, averaging about 224 mm. Check how your own bed drains and plan watering around actual soil moisture; monthly rain totals are not an irrigation schedule.
When should I plant sweet alyssum in Chengdu?
Aim for 16 Feb - 16 Mar in an average year. If you would rather not gamble on the weather, wait until 27 Feb - 27 Mar - by then frost has finished in nine years out of ten.
Can I plant sweet alyssum earlier in Chengdu?
The historical frost estimate is 7 Feb. For Sweet alyssum, an air-temperature model estimates soil warmth of about 10°C (50°F) around 16 Feb. This is not a soil measurement or a forecast. Check your bed at sowing depth; cold, wet conditions can slow growth and increase decay risk.
When might sweet alyssum flower in Chengdu?
The estimated period is 7-22 Apr, based on 50 to 65 days from the modeled planting date. Cultivar, planting material and growing conditions can change this interval; check the plant as well as the calendar.
How much frost will sweet alyssum tolerate?
Check the named variety and local forecast before exposing young growth. The catalog cold-damage figure is a reference, not a guarantee: plant age, acclimatisation, wind and the duration of a freeze affect damage.