A colorful annual, zinnias flower for most of the summer months. They come in a variety of flower forms, including single and double blooms. Zinnias grow well from seed, whether purchased or saved from existing plants. Many varieties are hybrids so saved seeds may not grow flowers exactly like the parent plant. Non-hybrid types produce seed that looks like the parent. Save seeds from several different zinnia varieties and label them so you can find the seeds that work best for your garden.
Leave the flowers on the stem after they begin to fade. Zinnia petals dry but they do not drop off until after the seed is ripe.
Cut the zinnia flower from the stem once the petals are papery and completely dry. Place the flower heads in a bowl as you collect them, which catches any petals that begin to drop off.
Pull the petals from the flower head one by one. Seeds are located at the base of each petal.
Hold a petal over a bowl. Rub the base of the petal between your thumb and forefinger, separating the seed from the petal. Drop it into the bowl. Repeat for each petal.
Label a jar or envelop with the zinnia variety and year harvested. Place the seeds inside and seal it closed. Store in a cool, dry place until you are ready to plant the following spring.
Zinnia seeds can remain viable for three or more years.