The Number of Weeks to Transplant Marigolds

Indoor Starts

• Marigolds start readily from seed. The African marigold (Tagetes erecta) takes about nine weeks from seed start to full growth, while the French marigold (Tagetes patula) and gem marigold (Tagetes tenuifolia) take five to six weeks. Check the last spring frost date for your area and subtract the growing weeks for your variety to estimate when to start the seeds. Fill a shallow tray with a soilless potting mix and plant the seeds one-quarter inch deep. If you keep the seeds warm at 68 to 72 degrees Fahrenheit, you can expect germination in five to seven days.

Prepare to Transplant

• Two weeks before the last expected frost, you can move your marigold starts to a warm shaded outdoor area, protected from the wind, for two to three hours in the afternoon. Put them out for gradually increasing periods of time each day in partial sun to accustom them to outdoor conditions. After two weeks, your marigolds can stay outside until it is time to transplant, unless an unseasonable freeze is expected.

Transplant Maturity

• In addition to waiting until all danger of overnight frost passes, your marigold start's size and maturity indicates when it is ready for transplant. When your seedlings reach two to three inches in height and develop two sets of true leaves, they are ready for transplant into the outdoor garden beds.

Transplant Time

• If you keep your starts at room temperatures of 68 to 72 F and keep them in a location where they receive the maximum benefit of daytime sunlight, your marigolds should reach sufficient size to transplant in four to six weeks. Choose a planting area with well-drained, organically rich soil that receives direct sunlight for six or more hours per day. Daytime temperatures should be regularly between 65 to 72 F and overnight lows not below 60 F.