Hi Mary,

Did you plant common milkweed (Asclepias syriaca)? 

Common milkweed wants full sun and it does like some moisture. I am guessing that the soil around your cedar hedge is very dry. It might also be shaded part of the day. That combination will not let common milkweed thrive. 

Common milkweed is usually found growing in "disturbed sites"--like along roadsides, in pastures, vacant lots, fields that are mowed and burned, etc. It is not usually found growing near trees. 

I would recommend finding a different location for your milkweed or choosing a different native plant. There are many native plants that are beautiful and feed adult monarchs as nectar sources OR that are host to different species of butterflies. I would recommend something like the blue wood aster aka heartleaf aster (Symphyotrichum cordifolium). I have it growing in part sun near a maple tree and it puts on a beautiful show of flowers during the fall months when monarchs are migrating and need food for their journey.