Grass trees (Xanthorrhoea spp.) are Australian natives. They can live up to 600 years, so the grass trees take their time growing: it can take up to 20 years for some species of grass trees to form the trunk, according to Colin Campbell of Gardening Australia. Grass trees require lots of sunshine and warm temperatures and won't survive outside of United States Department of Agriculture hardiness zones 9b to 11. Grass trees do not transplant well, so give each seed its own pot.
Combine equal parts of potting soil and perlite and pour it into the pot. Water the soil until it is moist and allow the water to drain from the bottom of the pot.
Place the grass tree seeds on the surface of the soil and cover them with 1/8 inch of sand. Pour the fungicide over the soil until it is drenched.
Place the pot in a sunny, warm area and keep the soil moist until the grass tree seed germinates. This may take from six weeks to one year, depending upon the species.
Fertilize the grass tree seedling when it reaches 4 inches in height. Use fish emulsion, at half the strength recommended on the package. Allow it to remain in a sunny, warm location while it grows.
Transplant the grass tree seedling into the landscape during its second spring. Dig a hole the same depth as the pot and twice the diameter. Place the roots into the hole and backfill with the soil from the pot, not the garden. Try to use as much of the original soil as possible.