Myrtle's tough, and I suspect you're giving them too much water. Most things don't like to be kept "wet". Cut back on the water and see what happens. Also, is it well drained? You don't mention yellowing of leaves, and that seems to me to be a sign of overwatering and/or poor drainage. Finally, could just be natural loss due to change of environment and weaning from intense amounts of fertilizer that most shops pump their plants up with.

Thanks for the info. I am sure you are right because the person at the shop where I got it said to "keep it wet," and I did. I think they are draining properly, though I looked more closely at one the the plants and it does have yellowing of some of its leaves. But I really think it was the overwatering. Maybe the lack of sun hasn't helped; we have had constant rain since I got the topiaries. Should I give them some fertilizer, and if so, do you know what kind? Thank you again.

Seems to me that fertilizer on a stressed plant isn't too good an idea, especially if you don't think the soil is really depleted. And lack of sun certainly hurts the water situation--nothings drying out and the plant isn't using as much water as it would. Let it dry out some for a while and see if that doesn't help before you do anything else.

I aslo have a myrtle topiary..... it only really seems to get thirsty when there is quite a bit of indirect sunlight, I live on the west coast of canada and we get a lot of cloud and rain, so it isnt particularly thirsty. They also like humidity, mine lives in the bathroom. Once it gets used to the temperature you should be able to fertilize it with miracle grow mixed with water about once a month. I find when i started to fertilize my myrtle it started to grow like CRAZY. Happy trimmings