Cut tulips are notorious for drooping over once cut and put into a vase. Their light stems and top-heavy flowers make drooping almost inevitable. You can reduce drooping by keeping them well-hydrated and providing them with essential nutrients. There are also a couple of techniques for keeping the stems erect.
Fill a tall, slender vase with water and add a floral preservative. Healthy tulips are likely to stand more erect than dehydrated, nutrient-deficient stems.
Recut the tulip stems at an angle about an inch from the bottom. Remove the foliage so none is submerged in water. Leave some foliage to help the tulips stand up.
Wrap the tulip stems tightly in plastic wrap, leaving the bottoms free to absorb water. Set the stems in the water for about five hours. Remove the plastic wrap and arrange them in the vase. This allows the tulips to absorb water, swelling the stems with water while erect.
Place the slender vase inside a bigger one if you prefer to use a bigger vase. You can also arrange more tulips around the slender vase inside the bigger one. This way you have tulips that are straighter and taller in the center and ones that droop along the outside.
Keep the tulips in a cool location and out of direct sunlight and drafts. Replenish the water frequently.