did you mulch well to avoid freeze/thaw cycles to avoid winter heave??

what zone are you

ken

I'm not sure planting perennials in september will give them enough time for strong winter roots. I'm in z5 so I usually plant perennials either in the spring or in august (those clearence plants) and mulch heavily if they're planted in sugust. you MUST mulch because freezing and thawing will push things out of the soil. If you've dug a flower bed, and tried to add compost each year, you'll find lots of stones each year even if you removed them the year before because the cycle moves things out of the soil