Having got to mid-October with barely so much as a touch of frost, a lot of tender plants like Cosmos and Dahlias are continuing to flower unimpeded. They are not producing blooms at the same rate as back in the summer, but we are finding it is still worth dead-heading plants to keep them going.
With plants that produce good seed heads for winter, such as Helenium and Echinacea, it’s a little harder to judge when to stop dead-heading. Stop too soon and they cease to produce blooms too early, continue dead-heading too long and they won’t have any seed heads left for the winter. Various factors make it difficult to judge when the right time is, but around now seems to be about right, depending on the weather.