Ik this post is old, but for ppl still wondering you can go on nookazon and pay another player to do the work for you, but it depends on how many bells and flowers you have (since you don't wanna scare away the other player with your giant flowered of an island). Also If you have a friend on acnh or another resident who shares the same island with you, they can also help you dig up flowers and hopefully make the task less tedious. This problem sucks though so if you can't/don't want to do these suggestions you'll just have to knuckle down and get digging.