Hi, welcome to GoY, it could be the position it's in, they like full sun to partial shade in well drained, deep humous rich soil, or it could have been affected by a frost, which has caused it to drop buds, Derek.

Hi Steve, yes you're right, if they're planted too deep, it doesn't flower very well, but these buds have formed and dropped off, so the planting depth must be ok, Derek.

variation in watering also has that effect too. so you need to monitor and make good the watering if it doesn't rain much.