How to Grow Purple Basil Seeds

Turn over your garden soil with a shovel in the early spring to prepare the bed for planting. Dig a spade into the ground and then turn the earth over. Break apart soil clods with your spade. Once you have loosened all the soil, broadcast 2 inches of manure or compost over the garden bed, then turn the nutrients into the soil with your spade. When the soil has no clumps and the manure or compost is integrated into the native soil, smooth the earth into an even layer with the flat side of your spade.

Wait for the last frost date in your area to plant the basil seeds.

Sprinkle the purple basil seeds over your garden bed in an even layer. over the seeds with 1/4 inch of soil. Water the soil lightly, until it gets moist but not saturated or boggy.

Keep the soil evenly moist until the seeds germinate, typically within one week. Basil seedlings have D-shaped leaves, with the flat sides of the D touching one another.

Allow the seedlings to grow until they have two to three pairs of true leaves. Water the garden bed until the soil becomes saturated, then allow it to dry out before watering again. Purple basil is especially susceptible to stress in its early stages, so don't give too much or too little water. If the plants are standing in water, you've over watered and should cut back next time. If the soil is bone dry, you've waited too long to water.

Thin out the seedlings when they have two to three sets of leaves, having 12 inches between plants.

Mulch the developing basil plants with 2 to 3 inches of straw, which can cut back on weed development and can keep moisture in the soil.

Fertilize the basil after you thin it out, and once more during the growing season. Apply 3 oz. of 5-10-5 fertilizer per 10 feet of basil plants, suggests the University of Minnesota.

Prune back your basil to harvest leaves. The plant will sprout new growth once cut, and trimming frequently prevents your basil from flowering, which will give it a bitter taste.