Where to plant Trillium
Nearly all Trilliums naturally grow in woodland conditions and most come from N. America. They will therefore be used to some level of decayed organic matter in the soil. These facts give us a clue as to where to plant them in British gardens. So in locating your Trillium planting position, choose some shade or at least a position that isn’t in full sun in the summer.
Mix some well decayed organic material in with the soil when planting. This can be garden compost, leaf mould or even really well rotted manure. In our experience, Trilliums are quite hungry plants and good feeding results in better growth and flowering. Please bear in mind that through autumn, winter and spring the plants must have enough moisture at the roots, but bad drainage is to be avoided. In most of N. America they are used to dry conditions during the heat of summer. If you are growing west coast Trilliums such as T. albidum, T. kurabayashii and T. chloropetalum the addition of sharp sand to most soils will be beneficial. Aim at 20-25% sharp sand which can be obtained from most reputable garden stores. Failing that we have found sharp sand from a builders’ merchant works just as well.
Depth of planting
Once the planting position has been decided, the next step is to think about planting depth. Were you to go to N. America to examine Trillium rhizomes in the wild, you would find that most of them are situated just below the leaf litter layer. This gives a crucial clue as to the depth of planting. 1-2” below soil surface is usually optimum. If a T. rhizome finds itself too high in the soil it has the incredible ability to drag itself deeper by means of contractile roots.
The rhizomes you receive from Twelve Nunns will have a number of living roots attached to them. These must be preserved at all costs. Without them the rhizome will take 2-3 years to establish an adequate new root system. So when planting, dig a hole deep enough to accommodate the roots as they would be in a natural state.
The rhizomes will be large enough to flower within the next year or two.