How to Start Marigolds

Fill a seed tray with sterile, slightly-moistened seed starter mix or 2 parts vermiculite, 2 parts perlite and 4 parts peat moss until 3/4 inch from the top. Ensure the tray has adequate drainage holes over its base. You can cover the holes with broken crockery or sphagnum moss to improve drainage before adding the mix. Shake the tray a couple of time to level the soil mixture because the seeds germinate in loose soil.

Insert the narrow end of a marker into the mix to form 2-inch-wide rows. Lower the seeds into the rows, spacing each evenly apart. Cover marigold seeds in the mix to a depth that equals two times the diameter of each. Because you are only using the same type of seed, you can also scatter it over the mix.

Spread a thin layer of vermiculite over the seeds and lightly moisten or place the tray in a container of water so it absorbs moisture from the base. Do not lower the tray in a deep container that causes water to run over the sides or top of the tray.

Insert the tray in a clear plastic bag or spread a polyethylene plastic sheet over it to help the seeds germinate, which usually takes five days to 1 week. Because the plastic sheet retains moisture, additional watering until germination is not necessary. Place the tray in a warm spot with consistent temperature between 65 to 75 degrees Fahrenheit.

Discard the plastic covering when the seeds germinate and move the tray to a southern window or spot with indirect but bright light. Suspend a two-bulb lighting fixture 4 inches over the tray to supplement poor lighting. Use a combination of cool white and warm white fluorescent light tubes in the fixture and keep it on for 16 hours every day.

Transplant seedlings to 3-inch pots when they develop their second sets of leaves. Fill the pot with quality potting mix before planting a seedling in it. Gently lift the marigold seedling by its leaves and lower it into the pot. After three days, move the pot to a window exposed to full sunlight. Let the marigold seedlings grow slightly taller before transplanting them to the garden soil after the danger of frost has passed.