After over ten years of beautiful lavender blossoms, this year they are only partially formed and very small (2"). The plant looks ok, some yellow leaves, but nothing serious (I hope). It is about 8 x 8 feet in a raised bed. It had fertilizer in March. The winter was very dry until May, but the total rainfall is now close to normal. Other plants near it are ok: lots of blossoms and great quality, too. What do you suggest?