Plant lemon balm in fertile moist soil in partial sun. Lemon balm is happy with shade during midday.
Prepare the planting bed. Add 1 inch of compost to the surface of the planting bed. Turn over the soil with a garden shovel. Rake the area smooth.
Sprinkle lemon balm seeds on the surface of the soil. Press in lightly with your hand. Cover with a fine layer of compost or vermiculite.
Water with a fine mist from a hose end sprayer. Mist daily as needed to keep the planting bed moist until the seeds germinate in 10 to 20 days. Water lemon balm the equivalent of an inch of rainfall per week.
Thin the seedlings when they are 3 to 4 inches high so they stand 12 to 24 inches apart.
Mulch around the plants to hold in moisture and discourage weeds. Apply a 2- to 4-inch layer of shredded leaves or buckwheat hulls.
Fertilize lemon balm plants in early spring by spreading all purpose granulated fertilizer around the plants. Pull back mulch and apply fertilizer following the manufacturer's recommended application rates. Replace mulch.
Protect the roots from freezing winter temperatures by applying a 12-inch protective winter mulch of fallen leaves. Remove the mulch in early spring.