My magnolia tree is very limp, I don’t know why

Thank you for contacting Yates. 

Try to feed the tree regularly with 'Yates Dynamic Lifter Soil Improver and Plant Fertiliser' as a complete, soil-conditioning  fertiliser. It's certified for use in organic gardens and will help create a nutrient rich soil for better root growth, stronger plants and more flowers and fruit! It can be used on gardens all year round, including native plants. Click here for more info on this product: https://www.yates.com.au/product/garden-fertilisers/certified-organics/yates-dynamic-lifter-soil-improver-plant-fertiliser