How to Grow Red Geraniums

Fill a plastic flat with fertilized potting soil within a half inch of the rim about six to eight weeks before the last frost. Poke four or five small holes in the bottom of the flat to ensure adequate drainage. Prepare three rows in the flat by lightly dragging a pencil from one end of the flat to the other. Place single red geranium seeds 1/8 inch apart along the rows, covering each seed with a light layer of soil. Use spray bottle to apply mist over the entire flat.

Place the flat in a garbage bag and close with a twist tie. Keep bag in 70- to 75-degree temperatures; light is not necessary during the germination process, which should take one to two weeks. Open the bag to check for sprouts after a week and remove from bag at first sign of sprouts. Keep soil moist.

Remove seedlings from flat when two leaves emerge from each red geranium. Transplant into dirt-filled, six-hole plastic containers like those used to sell annuals at garden centers. Place six-hole containers in a southern window. Feed once a week with a water-soluble fertilizer watered down to half strength.

Prepare seedlings for the garden by placing six-hole plastic containers outdoors for several hours per day, increasing the outdoor exposure each day for a week. Select a full-sun location. Be sure to apply 10-10-10 fertilizer to garden area before planting. Dig 4-inch-deep holes 8 inches to a foot apart. Place 2 inches of mulch in each hole. Plant 3-inch seedlings in the ground and cover roots with soil. Water to make the soil moist but not soaked.

Fertilize red geraniums with 10-10-10 liquid fertilizer mixture every two weeks for their first month in the ground. Provide an inch of water per week. Fertilize again late in the growing season to help blooms flourish prior to frost.