The large Asiatic tree magnolias dominate the colour show in the garden from early spring until the mass of other colour arrives later on in March. In a good year without cold frosts and damaging winds, they are the wonder of the large Cornish gardens and herald the end of winter and the start of warmer temperatures.  

These huge trees which flower before the leaves emerge in the spring are relicts from the beginnings of plant evolution. They vary in flower colour from white to a remarkable dark crimson red. The paler varieties especially can be seen in the woodland at a great distance even on murky days.    

Also in the garden at Tregrehan are another two groups of magnolias called Michelias and Manglietias. These are evergreen plants and vary in size from bushes to huge trees. They tend to flower later in the season; many have massed blooms and fill the woodland with scent. Rather tender in much of the UK, they thrive in the deep shelter of the garden at Tregrehan. Owen Johnson mentions 16 of these evergreen Magnoliaceae that are the largest of their type in the country showing how the garden is at the forefront of trialling these plants which have been recently been imported into the UK.