How to Start Zinnias from seed

Zinnias are easy to start, as long as you remember they don’t like having their roots disturbed, so you’ll need to be extremely careful when transplanting them. You can either direct-sow them after the last frost, or start them indoors, using grow plugs, which can be planted directly into the garden when the time comes.

Start them no more than four weeks before your area’s last-frost date; zinnias grow quickly and, if started too soon, will become leggy and root bound. Prepare grow plugs by moistening them thoroughly, and then place the seeds in the pre-formed holes. Zinnia seeds don’t need light for germination, so you can sow the seeds on the plugs and cover them with a thin layer of vermiculite or peat.

Place the potted seeds in an area that is 75-78°F and most will sprout in 5-7 days (some varieties require 7-10 days). Don’t water them from above; let them absorb water from the trays the plugs are sitting in.

Once the seeds have sprouted, place the seed trays under grow lights or near a sunny window. When the seedlings have one or two sets of true leaves, thin out the weaker plants and leave the strongest seedlings. As the zinnia plants get bigger, encourage root development by allowing the soil to dry slightly between waterings.