Horticulture


Growing Medium for Trilliums - compiled by Carl Denton carl@trilliums.co.uk www.trilliums.co.uk
When sowing seeds, sow in either good quality John Innes No 1 compost with equal quantity alpine grit, or otherwise sterilized loam, leafmould/pine needle duff, and small alpine grit (equal parts), and cover with alpine grit. Plastic pots 8.5cm square with extra depth I have found most suitable so the seedlings do not require potting on (which they resent) until after the second year of growth. I plunge my pots into a sand plunge but remember they may require two 13 week cold spells at just above freezing point to break their dormancy. I shelter mine with a sheet of glass from the worst of the winter rain but do not allow them to dry out. It is wisest to sow fresh seed as the germination is reduced by 90% if the seed is dried, Trillium rivale is the exception to this rule. Seed is best kept, for a short period, in the seed capsule, or moist kitchen towelling. Trillium are woodland plants which root deeply so should be grown in lightly shaded areas and do not like stagnant water or spring drought. They like a deep woodland soil namely one including leafmould or pine needles which is free draining.	Being mainly woodland plants they cannot support themselves in windy conditions so shelter them from moderate breezes or stronger winds. Pine needles when collected are best from the lower layers of the forest floor together with a little soil where the microrrhiza proliferate. This should be placed in a black plastic refuse bin liner with a small amount of lime and a small amount of general fertilizer and allowed to compost for a year. Leaves are best shredded, left in an open topped enclosure and will then rot quicker than usually These composted pine needles/leaf mould should be then mixed with an equal part of sandy grit and an equal part of John Innes No 2 compost or sterilized loam (microwave). This makes a free draining mixture but poor in nutrients and is used when planting outside or for pot culture. Some require extra loam or clay, others extra sand and others extra lime stone chippings but I will attempt to describe which of these in the following species list. All trilliums in the wild appear to have a mulch of dried leaves around them. When they are in active growth feed with Phostrogen or Vitex 111, 2 or 3 times each season.
T. angustipetalum	Standard mixture as above.
T. albidum	Mixture as above with some dolomite chippings.. Does not like direct sunlight in May
T. camschatcense	Above mixture well drained but always moist when growing and in flower. Dislikes any lime
T. catesbaei	Requires well drained leaf mould and pine needles with plenty of river sand ,neutral to acid and do not allow to dry out in the spring but can tolerate dry in late summer. Dappled sun only
T. cernuum .	Highly organic and wetter habitat. Prefers acid soil in semi shade cool and damp.
T. chloropetalum	Standard mixture. Requires moister situation and planting 6 inches deep. Will grow in sunlight in Edinburgh but needs dappled shade in Yorkshire. Dolomite chippings improve it.
T. cuneatum	A clayey loam round Atlanta, Georgia. Always in woodland with a mulch of dry leaves.
T. decipiens	Humousy light soil over limestone, woodland. In the wild I have found it growing in a silver sand/clayey mixture
T. decumbens	Have only found it growing in rocky scree in woodland
T. discolor	Sedementary soils Ca rich (Marble), semi shade
T. erectum	Neutral to acid soil likes rocky or gravelly sites, lightly shaded.
T. flexipes	Will take full sunlight as long as roots moist. Prefers limestone country and rich soil
T. foetidissimum	Growing in a clay mixture
T. govanianum	Pine needle mould 3 pts to washed river sand 1 pts. Since writing the latter mine has been growing happily in ordinary humousy soil.
T. gracile	Grows in sandy loam in woodland in Texas
T. grandiflorum	Easiest species to grow, likes neutral soil with humus and some limestone chippings. Can take considerable sunlight in Edinburgh.
T. hibbersonii	Grow it in alpine house in standard mixture.
T. lancifolium	Habitat is rocky wooded slopes, in neutral soils over limestone.
T. ludovicianum	Found it growing in sandy clay mix with mulch of leaves.
T. luteum	Prefers some limestone chippings in the compost.
T. maculatum	Humus over limestone light shade. I have also seen it growing in a clayey loam and also loam over silver sand.
T. nivale	Small so grow in pots. Prefers alkaline soil so mulch with limestone chippings and never let the pot dry out during the growing season or else it will immediately become dormant.
T. ovatum	Likes leaf mold mix above clay as long as acid. Will tolerate drier situation. This grows well for me in large pots but plant it in my garden and it slowly declines over 3 years. Said to grow in magnesium and calcium rich soils in the wild
T. petiolatum	Needs extra water with sandy loam but not water logging. Again likes magnesium and calcium rich soils
T. pusillum	Neutral to slightly acid soil not too fertile
T. recurvatum	Standard mix and will stand direct sunlight
T. reliquum	Sandy humousy soil over limestone semi-shade but again can be found in sandy clay mixture
T. rugelii	Relatively easy to grow, likes slightly acid to neutral soil, moist, semi-shaded situation.
T. sessile	Likes more water in neutral soil, in semi-shade
T. tschonoski	Damp sandy peaty compost
T. underwoodii	Sandy humousy soil over limestone in light woodland. In another woodland it was growing in a silver sand/clayey mixture
T. undulatum	Strongly acid moist soil with good drainage. Requires more shade and cool root run. The most difficult to grow. I have not succeeded yet.
T. vaseyi	Likes rocky or gravelly soils, humus rich, damp, neutral to acid, lightly shaded and provide wind protection as it is a large plant.
T. viride	Standard mixture with limestone chippings.

Pt. rivale (T. rivale)	Equal parts loam, grit and pine/leafmould. Prefers to be alkaline to neutral. Will grow in full sun but needs flooding with water daily in the spring but can withstand some drought when dormant.


Carl Denton Leeds, Yorkshire Tel 0113 2612205 Email Trilliums@compuserve.com