Certified GKH Gardening Expert
The nutrient content of the soil may be off - too much nitrogen and not enough phosphorus. Feed it some high phosphorus fertilizer or add bone meal to the soil to encourage blooming. Here is more information: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/phosphorus-plant-growth.htm
Thanks I will try that - all my other flowers are lovely though. Ill get some phosphorous fertiliser and bonemeal.