Planting seasons:

When reading gardening magazines, books, plant labels or the back of seed packets, it's sometimes difficult to decide when a 'garden season' starts and finishes. Below is a guide to which calender month, relates to which season. These all begin on the first of the month, so 'Early spring' starts on March 1st etc.

Table: Months vs. garden seasons
Month 'Garden season' Season
March Early spring Spring
April Mid-spring
May Late spring
June Early summer Summer
July Mid-summer
August Late summer
September Early autumn Autumn
October Mid-autumn
November Late autumn
December Early winter Winter
January Mid-winter
February Late winter

Meteorologically, a season starts on the first of the month, for example, winter starts on December 1st, spring on March 1st etc.

Astronomically, the seasons change on the equinox or the solstice (both of which vary by a day or two depending on the year). Spring starts on the spring equinox (around the 20th of March), summer starts on the summer solstice (20th or 21st June), autumn on the autumn equinox (around 23rd September) and winter on the winter solstice, (21st or 22nd December).