It seems I'm always a little late dividing them! They are so big and beautiful in full bloom, the bees working on them like crazy...then boom! I water them, or it rains, and there I am, out driving a couple of stakes around them and pulling them back up, and tying them so they don't flop again! I'll divide then this fall and start the whole cycle again! My learning curve must be a little flat!
2ofus,..you are not alone,..yes Salvia needs a little attention and timing,..as do quite a few other plants,..i always get caught out when Delphiniums first appear above the surface,..preparing for slugs,..slip up and they will destroy several plants,..however in your case its the tying up when the Salvia gets tall,..or they droop. Make a copy of the link below,..it might come in handy,..even if just to remind you . Salvia Plant Types: Growing Information And Care of Salvia Plants
The month you divide them is not as important as the temperature. May here is sometimes in the 90's but up north May is still considered Spring with much cooler temps. Dividing should not be done in either of those temperature extremes. Moderate temperatures are best or wait until the plant is dormant. Some suggest cutting about 1/3rd of the plant off the parent and transplanting it. Or you can just dig the whole thing up and replant it in a larger space so it can spread out its own. To keep them from being very floppy, trim them back after they bloom, they will grow back stronger and give you another round of blooms through the season.
