More than one plant is known as Surprise Lily. Are you referring to Lycoris radiata? If so, leave them undisturbed unless they are failing.

At Tryon Palace (the early colonial capital of NC), there is a woodland garden where surprise lilies/naked ladies/lycoris squamigera have naturalized over hundreds of years. The patch covers an acre or more.Spectacular. So no, you don't need to thin them.

Could be Lycoris squamigera

Common Name: Resurrection lily

dont make work for yourself.. in the name of doing what other peeps do ...

when you find some reason to do something.. then do it.. to please yourself ...

but dont go online and ask a bunch of strangers if you need to do more work in your garden ...

if they are moving out of the area you want them in .. dig them out ... if they are so crowded.. they dont give a good flower show.. thin them ... otherwise.. go find something else to do .... and the best thing you do in your garden.. is to grab a lawn chair and an adult beverage .... and sit there and think bout all the work you just saved.. lol ...unless its a marriage thing.. lol

when you can ID a goal.. then go accomplish said goal ... but dont let others set your goals .... unless its a marriage thing.. lol .. but then... you wouldnt be posting in a garden forum .. lol ..

ken

i'm never looking for more work. between my guitar repair shop & 40 beehives & the garden i've plenty to do. these surprise lilies just keep spreading. i was just wondering if they can get too crowded. i just planted 150 bare root pennsylvania carex in a couple areas hoping that they will make a dense groundcover & eliminate some work.