Creating a large arrangement with 500 red roses is a grand endeavor, ensuring an awe-inspiring display of beauty. Here are some flower care tips to maintain the freshness of such a magnificent arrangement:

1. **Preparation:** Upon receiving the roses, carefully unpack them and remove any packaging materials.

2. **Trimming:** Trim the stems of the roses at a diagonal angle, cutting about an inch off the bottom. This allows for better water absorption.

3. **Vase Selection:** Choose a large vase that can comfortably accommodate all the roses without overcrowding. Make sure the vase is clean before arranging the roses.

4. **Watering:** Fill the vase with lukewarm water, ensuring it covers at least half the length of the stems. Add floral preservative to the water if available, as it helps to extend the lifespan of the flowers.

5. **Arranging:** Start arranging the roses in the vase, working from the outer edges towards the center. Ensure that each rose has enough space and is evenly distributed throughout the arrangement.

6. **Placement:** Place the vase in a cool location away from direct sunlight and drafts. Avoid placing it near fruits or appliances that emit ethylene gas, as this can accelerate the wilting of the flowers.

7. **Water Refreshment:** Change the water every 2-3 days to keep it clean and fresh. Additionally, trim the stems by a small amount each time to promote water absorption.

8. **Misting:** If the environment is particularly dry, mist the petals of the roses lightly with water to keep them hydrated.

By following these care tips, you can ensure that your large arrangement of 500 red roses remains fresh and beautiful for as long as possible, allowing you to enjoy its splendor for days to come.