Plant seeds in fiber pots now to ready for spring planting

It's time to start seeds for cold-tolerant, early-spring annuals that require a long lead time before being planted in the garden.

Follow directions on individual packets as to which types of seeds require bottom heat, light or darkness in order to germinate. You may need to do some research to find the specific germination requirements. Some seeds might require a short period of chilling, soaking in water or being nicked before being sown.

Cool-season annuals (larkspur, snapdragon, English daisy, ranunculus, pansy, annual poppy, forget-me-not, edging lobelia) can be planted outside in the garden by the second week in April after the young plants are hardened off. This may require starting seeds 14 weeks ahead in order to have blooming plants ready for outdoor planting.

Sow seeds in fiber pots or trays, using a pre-moistened, soilless or seed-starting mix. Sow large seeds in slightly indented rows and cover lightly with a thin layer of the mix. Finer seeds may be broadcast directly on top of soil. Some types of seeds will require a glass or plastic cover to provide supplemental humidity. Water seeds from the bottom or use a fine mister to keep the soil moist. Most seeds require a warm, bright location out of direct sun to germinate. Ventilate covered seeds daily, especially in bright conditions. You will need very good light to be able to successfully grow these early spring annuals to a big enough size to make a good display in the garden.

The spring season is short and there is not much time for these plants to develop and flower outside. Many of them will start to decline once the weather starts getting hot in summer.

When germination occurs, gradually increase light levels. Most seedlings require 14 to 16 hours of direct light to manufacture enough food to produce healthy stems and leaves. The characteristic legginess that often occurs when seedlings are grown on a windowsill indicates that the plants are not receiving enough light intensity, or enough hours of light. Use a full-spectrum fluorescent bulb that is placed no more than 3 inches away from the foliage.

When two sets of true leaves develop, transplant small seedlings to a larger fiber pot that contains a slightly coarser, "growing-on" mix and begin fertilizing with quarter-strength 10-10-10 solution. As the plants grow larger, switch to a half-strength solution once a week.

For more information on starting seeds, come to the Chicago Botanic Garden's Super Seed Weekend today, Jan. 22. Gardeners are invited to bring saved or leftover vegetable, flower and herb seed packets to share and swap with other gardeners. Beginners are welcome to participate even without seeds. Experienced seed savers will enjoy swapping with others at the Connoisseur's Corner.

Talk to experts about starting seeds indoors, seed saving and recommended varieties for Chicago gardens. Check our Seed Library at the Lenhardt Library. Visit the Seed Swap's Garden Shop booth to purchase seed-starting equipment, book and more. Bring the kids. Drop-in family programs feature a seed maze, making a sprouting necklace, and more.

• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.