i don't subscribe to that methodology, but if you do allow the plants to flower, you must dead- head. The flowers of ligularias do not age gracefully and should be lopped off as the rays blacken. This prevents seed production, so plants can put their energy into maintaining healthy leaves for the rest of the summer.

When should Ligularia be cut back?

Unless your Japanese Anemones have had a very good year, it's advised to cut them back in fall. Ligularia (Ligularia dentata) is predominantly grown for its foliage, which turns to a dark mush after frost. Feel free to cut it back. Lilyleaf Ladybell (Adenophora lilifolia) Can be cut back after flowering diminishes.

What plants should I not deadhead?

Some plants that will continue to bloom without deadheading include: Ageratum, Angelonia, Begonia, Bidens, Browallia, Calibrachoa, Canna, Cleome, Diascia, Diamond Frost Euphorbia, Impatiens, Lantana, Lobelia, Osteospermum, Scaevola, Supertunia petunias, Torenia, and Verbena.