Yes you can. You need to do it quickly and carefully, disturbing the rootball as little as possible. It's best to use a garden spade. Dig new hole first & add some plant food pellets to new hole. Encircle plant 4-5 inches from center stem. Go down and under the cow slip plants, lifting a big dirt ball along with the whole plant. Gently place plant with dirt ball into prepared hole. Tamp it down but not too much. Water in. The three plants may droop for a day or two, but will perk up and be fine.

I would wait until they've finished flowering and remove the flowering stems so they aren't using energy to make seeds. But it would be better done earlier in the year when they are just starting to grow.

Have to agree with both answers. There's always a 'best' time to move things and this isn't that time for primulas, but I move stuff all the time and as long as you do it carefully and tend things afterwards and accept they will probably sulk, it usually works ok in the end.

I agree with Stera wait until they have finished flowering and then move!

Oh Wow! I move mine any time of the year, split them and replant them! But then I do have a lot, so perhaps it's not so vital, I am more careful with more precious Primulas! Depends if it's vital it's moved out of the lawn now, or if it can wait.

So do I but felt obliged to give the official advice...

This isn't the best time to move them, but if you had to, it can be done.

I move stuff at the "wrong" time, too. Plenty of soil around the rootball, the hole all prepared before the plant is dug up, and it's moved before it even knows about it. Of course, I would never advise anyone to do the same thing...