One of the aspects which is lacking from your photos is bokeh. In all three photos, and especially the last two, the background is too sharp; I imagine that the photos were taken around 𝑓/5.6. By using a faster lens, you can isolate your subject from the background. Here's an example, which is far from being a good photo (especially since the composition is wrong), but still illustrates my point:
Shot at 50mm 𝑓/2.8.
Even with bokeh, flowers in the foreground and flowers in the background will rarely make a great photo. It is much easier to shoot the flowers on a background such as the sky or the grass to ensure enough contrast between the flowers and the background. The following photo shows a common mistake I make when shooting flowers:
While bokeh is here, the background at the top of the photo is virtually the same as the petals of the flowers. With not enough contrast, the subject is lost. It would be better to recompose the photo to include the blue sky or the green grass. A dark background won't work here, because of the dark branch at the bottom of the photo.
Note that entirely flat backgrounds may look boring. For instance, on the next photo, it is unclear if the background is actual grass or an artificial background:
Poor composition and the annoying out-of-focus flower in the top middle of the photo make the photo even worse.
When using 𝑓/2.8 or a larger aperture, it is essential to keep most of your subject in focus. Out-of-focus flowers which fill a large part of the photo should be avoided. In general, blurry elements which are closer to the camera compared to the in-focus subject look wrong, but if they are further away, it may look OK.¹
For instance, the next photo is an example of wrong focus: the flower in the middle of the photo is blurry, which makes the whole photo look blurry and badly done. However, the flowers on the right side don't look particularly wrong, since they are further from the camera and are at the edge of the photo.
Too much is too much
It's also better in general to avoid shooting too many flowers at the same time.
For instance, in the following photo, colors are nice, but there is absolutely no subject to focus on.
It might be more interesting to focus on individual flowers, and compose the background with both the dark leaves from the center of the photo and the yellow flowers behind them. The leaves will give enough contrast between the in-focus flowers and the yellow bokeh. This would bring another benefit of getting rid of the grayish sky at the top of the photo: since the goal here is to fill the photo with the yellow color, the sky is annoying.
Make the photo interesting
All illustrations below are from 1x. Click on each photo to go to the corresponding page.
Aside from their technical issues explained above, all the photos I've shown have one flaw: they are snapshots, not works of art.
The way you compose the shot may make a difference between a snapshot and a photograph one would like to display on a wall. You may either make the flower itself a work of art:
Photo by Jacky Parker.
Or combine it with other elements, such as insects:
Photo by Fabien Bravin.
or use it as an essential part of your composition:
Photo by Takanobu Nushi.
¹ This doesn't mean you should focus on the closest object in every photo. For instance, if you are shooting portraits, you'll usually focus on the eyes, even if it means that the nose will be slightly out of focus at 𝑓/1.8.