Gardeners often turn to marigolds (Tagetes spp.) in their gardens because they are reliable annuals that bloom from spring until fall. Although marigolds are easy-care plants -- no pruning or fertilizer needed -- they sometimes grow tall and leggy instead of bushy and full of blooms. If you start your marigolds from seed, indoors or out, be sure the seedlings will have the needed light, water and room to grow properly; the lack of any one of these can cause legginess.
Starting Seeds Indoors
Fill seed flats or small seed pots about three-quarters full with a high-quality seed-starting potting mix. About six to eight weeks before the last spring frost, sow two or three seeds per compartment or pot, and cover them with 1/2 inch of soil. Keep the seeds at room temperature out of direct sunlight, and water well to maintain moist soil conditions. Expect the seeds to germinate in five to seven days.
Place your potted marigold seedlings in an area that gets six or more hours of direct sunlight, or place them 4 to 6 inches from two 40-watt fluorescent bulbs. Leave the lights turned on 12 to 14 hours a day. Maintain the temperature between 60 and 70 degrees Fahrenheit during this stage.
Water your seedlings whenever the soil is dry to the touch, so the marigolds will grow well and develop strong root systems. Water until excess drips from the pots, then dump the excess water.
Snip the weaker plants at soil level with a pair of scissors; do not pull the plants, as that might disturb the other seedlings. Perform this task when the plants are 2 inches tall. Thinning marigolds ensures the plants have enough space to receive sufficient sunlight, nutrients and water and to fill out nicely.
Transplant your marigold seedlings after the first sets of leaves form. Individual peat pots that you can plant directly in the garden after the last frost work well. Use a high-quality potting soil; plant the seedlings with their base at soil level. Otherwise, plant them directly in the garden when the danger of frost has passed. Place them where they will get full sun, in soil amended with 2 or 3 inches of organic matter such as compost, and with 1 or 2 cups of slow-release 5-10-5 fertilizer for every 100 square feet of space. Plant marigolds 12 inches apart, or 24 inches apart for taller varieties.
Water your marigolds when the soil feels dry, giving it a 1-inch watering. Pinch off faded blossoms to encourage more blooms. Continue to care for marigolds in this manner even if they fall over because they have grown tall and leggy despite your efforts. Roots will form from fallen stems, developing better root systems so the plants will put forth bushier new growth.
Starting Seeds Outdoors
Turn the soil 6 to 8 inches deep in an area of the garden that receives six or more hours of sunlight. Work 2 or 3 inches of peat moss, compost or another form of organic matter into the turned soil, and for every 100 square feet of space, mix in 1 or 2 cups of a slow-release fertilizer labeled as 5-10-5. Cultivating the garden in this manner creates a loose, fertile and well-draining bed in which marigolds can develop strong root systems.
Sow seeds 1 inch apart and 1/4 inch deep after the last spring frost. Water with 1/2 to 1 inch of water. Keep the soil consistently moist as the seeds germinate and the seedlings become established in the garden.
Cut the weaker plants at ground level with a pair of scissors when they reach 2 inches tall, so the marigolds are spaced 12 inches apart, or 24 inches apart for taller varieties. Thinning ensures your marigolds will receive plenty of sunlight, nutrients, water and space to grow full and lush with lots of flowers.
Water and care for your marigolds as in Step 6 of Section 1.