My zinnia were slow going last year too...'Profusion' and 'Parks Cutting Blend', but took off middle June. This year I'd say it's been even slower growing for these and many others due to our below average temps. I have several varieties of Zinnia out there and barely coming up with 1st set of new leaves since planting mid May.
This is my 1st with Melampodium and those too are no bigger than when I planted out. Only 1 new set of leaves have grown (not even fully expanded) since and it's been a month. I'd leave them alone though.

Have any fish emulsion? They might like to have a drink of that I always give plants fish emulsion at 4 leaf stage and then they take off

My mellies are sitting too. Guess we will have to be patient. I bought some mellies as backup and they are wilty and sulky - not like my winter sowing sprouts - small but sturdy.

Same here on the Profusion Zinnias and I wanted them so badly. I planted 2 pkgs and didn't get many plants. They look like they are dying. In fact a lot of my annuals did not get roots and grow. I attribute it to the cold spring weather. I did a little pinching on the Profusions that are still there. Now I have lprobably killed them.

It's reassuring to hear others have had the same experience. I'll just keep my eye on them and hope for the best. Thanks!

Joanne

My Melampodium seedlings are just now starting to show some spurts of growth.. the heat wave we are having now will help, for sure.