over 10 years ago, we planted a few bulbs in one setting. The purpose was to enjoy the vertical purple flower and green growth it produces. As time went on, the horizontal growth of this plant has expanded to over 3 ft. Today it is quite a large dense growth with green branches that have grown out and just lie down sideways and have no flowers. The center of this mass has many bulbs tightly showing with some older dead woven straw intertwined. Question: After removing the dead straw, what will it take to get it back to normal with vertical flowers and vertical green growth, 1) does it need more water? 2)does it need more fertilizer? 3) Should some of the bulbs in the center be reduced to allow others to grow?
These bulbs need to be divided. A donut-like growth habit (dead in the center but growth around that) is always a sign that plants need to be divided. Ten years is also a long time to go without dividing bulbs. Bulbs are usually divided every 3-5 years. This article may help, though it's about dividing tulips, the method is the same.