Garden phlox · Brockton, Massachusetts, United States
When to plant garden phlox in Brockton
Main outdoor window
2-30 May
A climate estimate. Check your soil, forecast and cultivar.
Timed from last spring frost
18 April
In Brockton, on your chosen risk.
First flowers
1 Jul - 30 Sep
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 Brockton
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.
Plant out
2-30 May
Two weeks after your last frost.
In flower
1 Jul - 30 Sep
Garden phlox through the year
Against the frost risk in Brockton
Seasonal context
Rainfall and the growing season in Brockton
October has the highest average precipitation (123 mm); February has the lowest (85 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 Brockton
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 | -6.4°C (20.4°F)20.4°F (-6.4°C) | 1.7°C (35°F)35°F (1.7°C) | 27.2 |
| February | -5.8°C (21.7°F)21.7°F (-5.8°C) | 2.9°C (37.2°F)37.2°F (2.9°C) | 25.3 |
| March | -2.3°C (27.9°F)27.9°F (-2.3°C) | 7°C (44.6°F)44.6°F (7°C) | 22.4 |
| April | 2.7°C (36.8°F)36.8°F (2.7°C) | 13.2°C (55.8°F)55.8°F (13.2°C) | 6.8 |
| May | 8.4°C (47.1°F)47.1°F (8.4°C) | 19.2°C (66.5°F)66.5°F (19.2°C) | 0.0 |
| June | 13.8°C (56.9°F)56.9°F (13.8°C) | 24.2°C (75.6°F)75.6°F (24.2°C) | 0.0 |
| July | 17.7°C (63.8°F)63.8°F (17.7°C) | 28.1°C (82.6°F)82.6°F (28.1°C) | 0.0 |
| August | 17.2°C (62.9°F)62.9°F (17.2°C) | 28°C (82.4°F)82.4°F (28°C) | 0.0 |
| September | 13.4°C (56.1°F)56.1°F (13.4°C) | 24.2°C (75.6°F)75.6°F (24.2°C) | 0.0 |
| October | 7.5°C (45.5°F)45.5°F (7.5°C) | 17.3°C (63.2°F)63.2°F (17.3°C) | 1.0 |
| November | 1.7°C (35°F)35°F (1.7°C) | 10.5°C (50.9°F)50.9°F (10.5°C) | 11.1 |
| December | -2.9°C (26.8°F)26.8°F (-2.9°C) | 4.7°C (40.5°F)40.5°F (4.7°C) | 24.0 |
For garden phlox, 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 garden phlox for Brockton
- October is the wettest month in the rainfall grid, averaging about 123 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 garden phlox
Use the calendar to plan ahead, then check the conditions in your own garden.
- 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.
- Check mature size, drainage and cultivar suitability before choosing a permanent position. A suitable planting window does not guarantee long-term survival or fruiting.
Balance summer phlox moisture with space for airflow
Plant in fertile, drained soil with sun or suitable partial shade. Leave space for air movement between mature plants and water the soil rather than repeatedly wetting the foliage. Dry roots and crowded, humid leaves can create different problems at the same time.
Remove spent flower heads if you want to limit seedlings and assess further flowering. Seedlings may differ from the named parent; use division to retain a chosen cultivar. Remove affected debris and record recurring mildew so future spacing and cultivar choices are based on results.
What to record this season
Did mildew or dry soil limit the display, and did a different cultivar or spacing improve it? Add the cultivar, sowing date and conditions to your growing record so you can compare next season.
Further reading: NC State Extension: Phlox paniculata . 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
Plant in fertile, drained soil with sun or suitable partial shade. Leave space for air movement between mature plants and water the soil rather than repeatedly wetting the foliage. Dry roots and crowded, humid leaves can create different problems at the same time.
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. Garden phlox are timed with planting out 2 weeks after it, and this page simply resolves those offsets against the frost date computed for Brockton.
Brockton is zone 6b, 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 general establishment guide is around year 1, under suitable conditions. This is not a prediction for this location; cultivar, winter conditions and care determine whether it flowers reliably.
Also in Brockton
Other flowers to time
Growing garden phlox in Brockton
Can I grow garden phlox in Brockton?
The calendar estimates a planting window, not a guarantee of success. October is the wettest month in the rainfall grid, averaging about 123 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 garden phlox in Brockton?
Aim for 2-30 May in an average year. If you would rather not gamble on the weather, wait until 11 May - 8 Jun - by then frost has finished in nine years out of ten.
When might garden phlox flower in Brockton?
The estimated period is 1 Jul - 30 Sep, based on 120 to 150 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 garden phlox 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.