Ornamental grasses are versatile plants that can be the centerpieces or accents in garden areas. You can plant ornamental grass seed directly outdoors, but you get more bang for your buck when you start seed indoors. According to John Greenlee’s "The Encyclopedia of Ornamental Grasses," the seed is very small and easily blown by the wind. It is also susceptible to rain washout and bird predation and requires a layer of straw or burlap for protection. Try winter-sowing the seed instead. You improve germination rates when you plant ornamental grass seed inside in late winter, then transplant the seedlings.
Fill the cell pack with moist, but well-drained potting mix. The potting mix should be sterile to prevent damping-off, a soil-based fungal condition that causes seedlings to wilt at the stem. An ideal mix contains 1/3 soil, 1/3 vermiculite and 1/3 peat moss.
Place the ornamental grass seed on the potting mix surface then lightly press the seed into the mix. Plant 4 seeds per cell to maximize use of planting space, because not all seeds will be viable.
Place the cell pack in a sealed plastic bag during germination. The bag allows air exchange and retains enough moisture that no further watering is necessary during germination, according to the Ohio State University Extension Ohio Master Gardener’s Manual. The seed may take a week or longer to germinate, depending on the species.
Put the cell pack on a warming mat or on top of a refrigerator, as germination requires higher temperatures than those found in the average home. Do not overheat the cell pack, however.
Remove the cell pack from the bag after germination, or after two cotyledon leaves form.
Move the cell pack to a location that has plenty of light and cooler temperatures to optimize growth. Use a grow light or hang a 40-watt cool white bulb and a 40-watt warm white bulb above the plants to provide light during the day.
Use a spray bottle to mist the ornamental grass seedlings at least once a day to prevent the plants from drying out.
Harden off the plants when the majority of the seedlings are 1 inch high. Seed grown indoors needs to acclimate to outdoor conditions to prevent from wilting, so gradually increase exposure to full sun a few hours each day.
Plant the ornamental grass seedlings in full sun in compost amended soil anytime during the growing season. A rule of thumb is to space seedlings as far apart as the mature plant will become tall, or a little closer if you need quick ground cover. Use a shovel to dig holes slightly larger than the root ball, then add water to the hole. Place the root ball in the hole, then replace the soil.
Water every day until the seedlings become established, then water as needed through the growing season. Different species have different water requirements; in general tall species need more water.