A tender perennial, fennel is an herb that is often grown as an annual. All parts of the plant are usable, from the bulbous root to the stems, leaves and seeds. Like many herbs, fennel thrives in pots if planted correctly. Since this herb can reach 3 feet tall or more, it does require a larger container than some of the shorter kitchen herbs. Since fennel needs a long, warm growing season, pot culture is a feasible way to grow this herb successfully in cooler northern gardens.
Fill a 10 inch deep, 10 inch diameter pot with a moist potting mix. Leave a 1 inch space between the top of the soil and the rim of the pot.
Sow two fennel seeds ½ inch deep in the pot. Mist the surface with water then cover the pot with a plastic bag. Set the pot in a warm place for the seeds to germinate.
Remove the plastic bag once sprouts appear, usually within seven to 14 days of planting. Set the pot in a warm, sunny windowsill.
Water the fennel when the soil surface begins to dry. Water from the top of the pot until the excess moisture begins draining from the bottom of the pot.
Fertilize the fennel monthly throughout the growing season with a half-strength soluble houseplant fertilizer. Begin fertilizing four weeks after the seeds sprout.
Move the fennel outside once all frost danger has passed in spring. Set the pot in a warm, sunny area. Alternately, continue to grow the fennel inside in a sunny window.