People often forget that the agricultural cycle is one that spans the full year. Because of this it is important to honor Demeter at ANY time of year. After all she is the one who sends up from below a rich harvest for mortal man. The beginning of the agricultural year in Greece is actually in the fall, when crops like winter wheat are sown. Obviously this cannot happen in all parts of the Northern hemisphere, but where it can there usually are crops planted at that time.
There is a festival called the Proerosia that honors Demeter at this time. The festival was originally held at Eleusis after the Delphic Oracle ordered an offering of “first fruits” to Demeter and was usually held a day or two prior to the Pyanepsia. This would be a good time to remember her with the Homeric Hymn to her as well as the Orphic Hymn to Eleusinian Demeter. It is also a good time to do some baking as some of the offerings to Demeter were traditionally made up of grains. Just remember that sometimes it is okay that the offering be either small or non-physical in nature.
Other ways to celebrate the Proerosia might be to volunteer with the harvest at a community garden (helping the elderly or children to get in their crops) or even to volunteer some time at a local food bank as an offering to the goddess. We need to be creative in our thinking as the old festivals are not always easy to either recreate or revive.