When to plant in Norristown, PA
Planting dates worked out from Norristown's own frost records, not a generic zone chart.
Safe to plant out
May 10
1 year in 10 has a later frost
Average last frost
Apr 21
about a 50% chance of a later one
Average first fall frost
Oct 23
1 year in 10 by Oct 9
Frost-free days
186
median, 1991–2020
Station used: Phoenixville 1 E · 12.6 km away · station 43 m, town 48 m. How we match towns to stations
This season
Plan your garden.
Planting dates for common crops
| Crop | Start indoors | Plant out or sow | Harvest from |
|---|---|---|---|
| Tomato | Mar 15 – Mar 29 | May 10 – May 24 | Jul 4 |
| Sweet pepper | Mar 1 – Mar 15 | May 10 – May 24 | Jul 9 |
| Lettuce (leaf) | Feb 17 – Feb 24 | Mar 24 – Apr 7 | May 3 |
| Peas | — | Mar 20 – Apr 17 | May 14 |
| Bush beans | — | May 3 – May 24 | Jun 22 |
| Carrot | — | Mar 31 – May 12 | May 30 |
| Beet | — | Mar 31 – May 12 | May 20 |
| Potato | — | Mar 31 – Apr 21 | Jun 9 |
| Kale | Feb 13 – Feb 27 | Mar 27 – Apr 10 | May 9 |
| Broccoli | Feb 10 – Feb 24 | Mar 24 – Apr 14 | May 23 |
| Cucumber | Apr 12 – Apr 19 | May 10 – May 24 | Jun 29 |
| Summer squash and zucchini | Apr 12 – Apr 19 | May 10 – May 24 | Jun 24 |
| Winter squash | Apr 12 – Apr 19 | May 10 – May 24 | Jul 29 |
| Sweet corn | — | May 3 – May 24 | Jul 2 |
| Onion (from sets) | — | Mar 24 – Apr 14 | Jun 22 |
| Garlic | — | Oct 9 – Nov 6 (fall) | following summer |
| Spinach | — | Mar 20 – Apr 17 | Apr 27 |
| Basil | Mar 29 – Apr 12 | May 10 – May 24 | Jul 6 |
Norristown's weather over time
How the growing season has shifted here, year by year, from the station's own records.
Each year's last spring frostLong-term trend
See the data as a table
| Year | Last spring frost |
|---|---|
| 1894 | Apr 12 |
| 1915 | Apr 16 |
| 1916 | Apr 11 |
| 1917 | Apr 17 |
| 1918 | Apr 15 |
| 1919 | May 4 |
| 1920 | Apr 11 |
| 1921 | Apr 12 |
| 1922 | Apr 29 |
| 1923 | Apr 26 |
| 1924 | Apr 24 |
| 1925 | May 8 |
| 1926 | May 25 |
| 1927 | Apr 25 |
| 1929 | Apr 24 |
| 1930 | Apr 26 |
| 1931 | May 1 |
| 1932 | Apr 17 |
| 1933 | Apr 28 |
| 1934 | Apr 29 |
| 1935 | Apr 17 |
| 1936 | May 29 |
| 1937 | May 1 |
| 1938 | May 13 |
| 1939 | Apr 21 |
| 1940 | Apr 29 |
| 1941 | May 13 |
| 1942 | May 11 |
| 1943 | May 5 |
| 1944 | Apr 19 |
| 1945 | May 2 |
| 1946 | May 10 |
| 1947 | May 11 |
| 1948 | May 9 |
| 1949 | May 22 |
| 1950 | May 9 |
| 1951 | May 14 |
| 1952 | May 3 |
| 1953 | Apr 22 |
| 1954 | May 7 |
| 1955 | Apr 9 |
| 1956 | May 25 |
| 1957 | May 4 |
| 1958 | Apr 14 |
| 1959 | Apr 13 |
| 1960 | May 4 |
| 1961 | May 5 |
| 1962 | May 10 |
| 1963 | May 24 |
| 1964 | May 3 |
| 1965 | Apr 21 |
| 1966 | May 11 |
| 1967 | Apr 26 |
| 1969 | Apr 13 |
| 1970 | May 7 |
| 1971 | Apr 24 |
| 1972 | May 11 |
| 1974 | May 8 |
| 1975 | Apr 22 |
| 1976 | Apr 13 |
| 1977 | Apr 10 |
| 1978 | May 1 |
| 1979 | Apr 20 |
| 1980 | Apr 17 |
| 1981 | Apr 22 |
| 1982 | Apr 23 |
| 1983 | May 10 |
| 1984 | Apr 22 |
| 1985 | May 4 |
| 1986 | May 10 |
| 1987 | Apr 10 |
| 1989 | Apr 24 |
| 1990 | Apr 20 |
| 1996 | May 14 |
| 1997 | May 8 |
| 2002 | Apr 26 |
| 2003 | Apr 14 |
| 2004 | Apr 16 |
| 2005 | May 5 |
| 2006 | Apr 11 |
| 2007 | Apr 14 |
| 2008 | May 11 |
| 2010 | Mar 28 |
| 2011 | Mar 30 |
| 2013 | Apr 22 |
| 2014 | Apr 21 |
| 2015 | Apr 25 |
| 2016 | Apr 14 |
| 2017 | Apr 9 |
| 2018 | Apr 21 |
| 2020 | May 9 |
| 2024 | Mar 26 |
| 2025 | Apr 9 |
Each year's frost-free daysLong-term trend
See the data as a table
| Year | Frost-free days |
|---|---|
| 1894 | 202 |
| 1915 | 177 |
| 1916 | 182 |
| 1917 | 172 |
| 1920 | 213 |
| 1921 | 183 |
| 1922 | 172 |
| 1923 | 163 |
| 1924 | 172 |
| 1925 | 155 |
| 1926 | 153 |
| 1929 | 167 |
| 1930 | 177 |
| 1931 | 170 |
| 1933 | 169 |
| 1935 | 170 |
| 1936 | 148 |
| 1937 | 160 |
| 1938 | 143 |
| 1939 | 176 |
| 1940 | 150 |
| 1941 | 166 |
| 1942 | 136 |
| 1943 | 136 |
| 1944 | 179 |
| 1945 | 154 |
| 1946 | 156 |
| 1947 | 138 |
| 1950 | 159 |
| 1951 | 138 |
| 1952 | 167 |
| 1953 | 168 |
| 1955 | 196 |
| 1956 | 137 |
| 1957 | 145 |
| 1958 | 174 |
| 1959 | 188 |
| 1960 | 169 |
| 1961 | 152 |
| 1962 | 167 |
| 1963 | 122 |
| 1964 | 155 |
| 1965 | 167 |
| 1966 | 159 |
| 1967 | 178 |
| 1969 | 192 |
| 1970 | 165 |
| 1971 | 194 |
| 1972 | 151 |
| 1974 | 148 |
| 1975 | 191 |
| 1976 | 181 |
| 1977 | 202 |
| 1978 | 160 |
| 1979 | 172 |
| 1980 | 188 |
| 1981 | 170 |
| 1982 | 177 |
| 1983 | 164 |
| 1984 | 194 |
| 1985 | 156 |
| 1986 | 129 |
| 1987 | 181 |
| 1989 | 168 |
| 1990 | 182 |
| 1996 | 142 |
| 2002 | 188 |
| 2003 | 191 |
| 2004 | 201 |
| 2005 | 175 |
| 2006 | 206 |
| 2007 | 197 |
| 2008 | 161 |
| 2013 | 186 |
| 2014 | 181 |
| 2015 | 175 |
| 2016 | 194 |
| 2017 | 214 |
| 2018 | 179 |
| 2020 | 178 |
| 2024 | 215 |
| 2025 | 200 |
Each year's average temperature, April to SeptemberLong-term trend
See the data as a table
| Year | Growing-season temperature |
|---|---|
| 1894 | 19.1 °C |
| 1915 | 19.3 °C |
| 1916 | 19.2 °C |
| 1917 | 18.0 °C |
| 1920 | 19.0 °C |
| 1921 | 20.2 °C |
| 1922 | 19.7 °C |
| 1923 | 19.2 °C |
| 1924 | 17.6 °C |
| 1925 | 19.4 °C |
| 1927 | 17.7 °C |
| 1929 | 19.7 °C |
| 1930 | 20.6 °C |
| 1931 | 21.1 °C |
| 1933 | 20.9 °C |
| 1934 | 20.6 °C |
| 1935 | 19.5 °C |
| 1936 | 20.9 °C |
| 1937 | 19.5 °C |
| 1938 | 19.7 °C |
| 1939 | 19.9 °C |
| 1940 | 18.3 °C |
| 1941 | 20.2 °C |
| 1943 | 20.6 °C |
| 1944 | 20.5 °C |
| 1945 | 20.3 °C |
| 1946 | 19.1 °C |
| 1947 | 20.3 °C |
| 1950 | 18.2 °C |
| 1951 | 18.6 °C |
| 1952 | 19.8 °C |
| 1953 | 19.8 °C |
| 1954 | 19.2 °C |
| 1955 | 19.9 °C |
| 1956 | 18.3 °C |
| 1957 | 20.1 °C |
| 1958 | 18.6 °C |
| 1959 | 20.3 °C |
| 1960 | 19.2 °C |
| 1961 | 19.0 °C |
| 1963 | 18.4 °C |
| 1964 | 18.8 °C |
| 1965 | 19.3 °C |
| 1966 | 18.8 °C |
| 1967 | 18.6 °C |
| 1968 | 19.3 °C |
| 1969 | 19.9 °C |
| 1970 | 19.9 °C |
| 1971 | 19.0 °C |
| 1972 | 18.2 °C |
| 1973 | 19.8 °C |
| 1974 | 18.7 °C |
| 1975 | 18.8 °C |
| 1976 | 19.3 °C |
| 1977 | 19.5 °C |
| 1978 | 19.2 °C |
| 1979 | 19.1 °C |
| 1980 | 20.3 °C |
| 1981 | 19.5 °C |
| 1982 | 18.7 °C |
| 1983 | 19.7 °C |
| 1985 | 19.1 °C |
| 1986 | 18.2 °C |
| 1987 | 19.9 °C |
| 1989 | 17.9 °C |
| 1990 | 18.1 °C |
| 1993 | 18.6 °C |
| 1995 | 18.9 °C |
| 1996 | 18.1 °C |
| 2000 | 18.4 °C |
| 2002 | 20.0 °C |
| 2003 | 18.9 °C |
| 2004 | 20.0 °C |
| 2005 | 20.2 °C |
| 2006 | 19.9 °C |
| 2007 | 20.8 °C |
| 2008 | 20.1 °C |
| 2010 | 21.5 °C |
| 2013 | 19.5 °C |
| 2014 | 20.0 °C |
| 2017 | 20.3 °C |
| 2018 | 20.8 °C |
| 2019 | 21.5 °C |
| 2024 | 20.7 °C |
| 2025 | 20.6 °C |
What this means for you: Since 1894, Norristown's last spring frost has come about 1 day earlier per decade, on average. The frost-free season has grown by about 2 days per decade. Year-to-year swings are large, so keep using the safe date rather than the trend.
Source: daily records from Phoenixville 1 E (NOAA GHCN-Daily). Years with too many missing days are left out.