Growing hostas from seed may not be an efficient method of propagation, and there are no guarantees regarding what the offspring will look like, or even if the seeds will germinate. But many hosta lovers embark on this gardening adventure anyway, despite the time, effort and uncertainty involved. Some gardeners try their hands at hybridizing, while others just let nature do the pollinating. According to Tony Avent of Simple Pleasures Nurseries, hostas from seed take three years to flower and from five to eight years to exhibit their mature foliage. Even if the parents are variegated, many hostas from seed are green. Other common foliage colors are blues and golds.
Leave the flowers and the flower stalks on the hosta. Elongated seed pods will develop on the stalks in a configuration similar to the flowers. The seeds will begin to ripen in the seed pods and the pods will grow larger.
Check the seed pods periodically. When the pods split, the seeds inside should be black. Cut off the entire flower stalk and place it on the cookie sheet or on the plastic tray covered with the wax paper, then set it in a dry place away from heat and the sun. Let the seed pods dry for two to three weeks. According to Trudi Davidoff of Wintersown, a website dedicated to seed growing, this method allows the seeds to fully ripen.
Harvest the hosta seeds after two to three weeks of drying. Open the pods if they haven't split apart on their own and harvest the seeds. If any seeds are not black, discard them as they will not germinate.
Fill the quart-sized pots with the seed-starting mix and press down on the mix without compacting it. The soil level should be 3/4 inch from the rim of the pot. Sow the seed on the surface of the seed-starting mix. Shirley, a successful hosta grower and author of the website Choosing Voluntary Simplicity, recommends planting several seeds from the same parent in each pot. Cover the seed lightly with the seed-starting mix. Write the name of the parent plant on the side of the pot.
Moisten the mix from the bottom by placing the pots in a sink filled with an inch of water. Let the water drain out when the mix in the pots is moist but not soggy. Cover the pots tightly with the plastic wrap and move them to a warm, dark place.
Take the plastic wrap off the pots when the seeds germinate. This may take two weeks or longer. Place the pots in a sunny window or under fluorescent lights for 10 to 12 hours a day.
Transplant your hosta seedlings to their own containers when they have three leaves, according to hosta hybridizer Stuart Asch. Lift gently with the plastic fork. Discard any broken or unhealthy plants. Shirley uses 2-ounce plastic cups. She pokes holes in the bottom of each cup and uses fresh potting mix. Keep the plants in the sunny window or under the lights.
Use the 4-ounce cups with drainage holes to transplant the seedlings when they outgrow their containers. If the plants are top-heavy or the leaves fill the surface of the cup, it's time to transfer them. When the plants have outgrown their second containers, Shirley transplants each one to the quart-size pot.
Begin to shorten the time the plants are under the lights. If you've grown them in a window, you don't need to move them away from the natural light.
Bring the hostas outside when the weather is reliably warm and won't go below 50 degrees. Set them in a shaded area for the day. Bring them inside at night. Leave the pots outside if the night temperatures will be above 50 degrees.
Transplanting Into the Garden
Plant your hostas in the garden when all danger of frost has passed. Choose a site that gets no more than three to four hours of sun. Avoid an area that gets sun during the midday hours. The soil should be well-drained.
Turn over the soil and amend with compost. Dig a hole large enough to accommodate the depth and width of the pot.
Make sure the surrounding soil is loose enough for the hosta's new roots to penetrate. Space your hosta seedlings 18 inches apart.
Set the plant in the hole and backfill with soil. Water so that the soil around the hosta is moist. Do not saturate.
Make sure your hostas have sufficient water. If the weather has been dry for 3 to 4 days, water thoroughly until the soil is moist. Fertilize with balanced liquid fertilizer diluted to a 1/4 strength after the plant has been in the ground 2 to 3 weeks.
Mulch your hostas with straw in late fall.