I planted a five year old tree 10years ago to celebrate the birth of my grandson. The garden runs to the sea in Cobh. It was too exposed and did not fare well so I moved it to a sheltered position in the walled garden about 5 years ago but it has not done well. It is very woody, few leaves, no flowers, except for last year when we had 2. I have been advised to treat it with sequestered iron and did so last and this year. I really do not want to lose it for good sentimental reasons.
Frist make sure it is not too deeply planted. The first root should join the stem now more than 5cm below the soil surface. If it does, too-deep planting can be fatal and the tree have to be lifted again and re-planted in autumn.
Assuming it is not too deeplly planted, it must have no competition from other plants, weeds or grass for at leave two metres diameter. Make sure it is not rocking in the ground. Prop it with 3 stakes if necessary.
Mulch with rotted leaves to about 8cm and water during any dry spell. Do not feed with granular fertilisers until growth actively resumes but you could water on a watering can of Miraclegrow every month in the meantime.
Watch for snail damage to the foliage, snails climb magnolia trrees to get the leaves. You will see the dried out shiny slime trails.