How to Make a Moss Tray

Sphagnum moss from peat bogs provides a soilless growing medium.

A moss tray made of sphagnum moss, also called peat moss, provides a protective growing medium for seedlings. In addition to offering plenty of air for plant roots, ground sphagnum moss, also called milled sphagnum moss, may prevent certain seedling diseases, according to the University of Missouri Extension. Moss trays allow you to start numerous seedlings in relatively little space and are convenient to carry from a sheltered location into the garden for planting.

Things You'll Need

• Plastic or fiber tray or wooden flat with small drainage holes
• Clean board that fits inside the tray
• Ruler
• Milled sphagnum moss
• Vermiculite or perlite (optional)
• Biodegradable paper towels (optional)

Instructions

1. Fill a tray to within ¾ inch of the top with milled sphagnum moss. Press the moss down with a clean board to create a firm growing medium.

2. Press the edge of a ruler into the moss to create shallow rows for the seeds 1 to 2 inches apart. Growing seedlings in rows simplifies thinning them, and makes it easy to tell different types of plants apart. To grow one type of seed per moss tray, it's fine to scatter the seeds on the moss without using rows.

3. Spread dry vermiculite or milled sphagnum moss over the seeds. Cover the seed to a depth double the diameter of the seeds, except for tiny seeds. Fine seeds, including petunia and lettuce, need light and should be left uncovered.

Tips & Warnings

• Shallow trays for starting seedlings and growing plants are also called flats.

• Raise the humidity for your seedlings for germination, if needed, by enclosing the seed tray. For example, use a clear plastic cover with ventilation holes to provide light and air. Garden centers carry suitable trays and covers for seedlings.

• Mix milled sphagnum moss with equal part of vermiculite or perlite, if desired. Vermiculite or perlite can aid in maintaining moisture in the growing medium. Consistent moisture is important for germination. Keeping the moss by itself consistently moist also works well. Fertilize the seedlings soon after they sprout; these growing mediums don't provide nutrition for the plants.

References

• University of Missouri Extension: Starting Plants Indoors From Seeds
• Purdue University; Growing Trees from Seed; B. Rosie Lerner; September 2000