Prepare the germinating container by filling it to within 1/2 inch of the rim with a quality seed-starting mix. Make sure the mix is soilless, to avoid damping off, a seed and seedling fungal disease.
Push the Romanesco broccoli seeds 1/2 inch into the soil. Space them at least 1 inch apart. Spacing is important with broccoli to prevent legginess. Cover them lightly and don't press the soil over them.
Place the flat in an area with lots of indirect sunlight. Romanseco broccoli seeds germinate within 10 days.
Transplant the broccoli seedlings into the garden five weeks after they sprout. They prefer cool weather, so if there is still one frost expected, they will be fine.
Prepare the planting area -- a 3-by-5-foot bed for 15 Romanesco broccoli seedlings -- by adding a 3-inch layer of compost to the soil and mixing it to a depth of 6 inches.
Plant the seedlings at the same depth as they are growing in the flat. Water them after transplanting to a depth of 6 inches.