How to Grow Gladiolus From Seed

Gladiolus flowers grow along tall flower spikes, producing blooms in every color but true blue. They have tall, sword-like leaves similar to those of their close relative the iris. The plants grow from a bulb-like structure called a corm. As tender perennials, gladiolus cannot tolerate periods of frost, so the corms are usually dug and stored indoors over the winter months. You can also start new plants from seed, either purchased or seed collected from your existing plants.

Pot

Potting mix

Tray

Plastic bag

Mesh bag

Fill a pot with a moistened seed-starting potting mixture. These mixtures usually consist of peat, perlite and other non-soil mediums.

Sow one seed per pot, placing it on the surface of the potting mixture. Cover the seed with a thin layer of soil no more than 1/8 inch.

Fill a shallow tray with 1 to 2 inches of water. Set the pot in the water and allow the potting mix to absorb the moisture until the soil surface becomes wet. Empty the remaining water from the tray.

Cover the pot with a plastic bag to help retain soil moisture during sprouting. Set the pot in a warm, 75 to 80 degree F room to germinate.

Remove the plastic bag once the seeds germinate. Move the pots to a sunny window and water them when the soil surface begins to dry.

Move the pots outdoors to a warm, sunny area once all frost danger is past. Allow the plants grow in the pots until the foliage dies back naturally in fall.

Remove the corms from the pots once the foliage dies back. Store the corms in a mesh bag in a dry, 40 degree F location. Transplant them outside in spring when all frost danger is past.

Plant most gladiolus seeds in spring six weeks before the last expected frost. A few varieties bloom in winter in mild climates, these must be planted in the fall.

Gladiola seeds remain viable for up to one year.