The root system is very hard and stiff, not flexible at all. I soaked it in a bucket of water for 15 minutes, and no change. Is this normal?

The Diamond Spire Gardenia, like many plants, can have stiff and inflexible roots. Soaking it for 15 minutes may not noticeably change the root structure. If you're preparing to plant it, you can try gently loosening the roots by hand, but be careful not to damage them. Proper planting techniques are more critical for the plant's success. Ensure the hole is deep and wide enough to accommodate the root ball, and water the plant thoroughly after planting to help it establish in the new location. Additionally, using a root stimulator during planting can aid in root development and growth. Proper care and watering after planting are key to a healthy gardenia's establishment and growth.