Planting basil from seed is truly enjoyable. Seeds germinate slowly, a bit faster when heated from below, and basil enjoys hot weather and full sun. Be sure to try Thai basil, holy basil, and Genovese basil — each variety has its own characteristics. Follow along with this handy How to Grow Basil from Seed Guide and grow some flavour.
When I Get My Seedling Home
Keep seedlings under very bright light to prevent legginess. Artificial lights are ideal, but a bright (ideally, south-facing) room will work for the short term. You may have to pot on seedlings more than once before they go out to allow for root growth. This is done by transplanting them into a slightly larger container with enough additional soil to keep the container mostly full. Keep the soil moist by daily watering and allow for free drainage so the plants are never sitting water.
Transplanting
Do not transplant outside until night time temperatures are steadily 10°C (50°F) or warmer. This may mean keeping seedlings indoors for up to a month. The plants should not require any fertilizer until transplant time.
Growing
Use any rich, loose, well drained soil. Once plants are 15cm (6″) tall, pinch out the growing tips to encourage really bushy growth prior to harvest. Watch for signs of flower buds forming in mid-summer, and pinch these off to promote more foliage.
Harvest
Frequent harvesting will prolong the life of the plant. Basil leaves have the best flavour just before the plant flowers, and if you plan to preserve some of your basil or make a big batch of pesto, this is the best time to harvest. Flowering can be delayed by pinching or clipping off new flower buds.
Tear basil rather than chop with a knife because when you chop you will notice the basil going dark. The oil stays in the leaf and does not properly flavour your food. Try to add just before serving so as to get the full aroma and effect. Cooking for any length tends to make the minty side of basil come to the forefront.
Basil is best fresh, but can be preserved by drying or by freezing. To do this, tear the leaves into small pieces and freeze small batches of them, with water, in ice cube trays. Once frozen, the cubes can be saved in zip-lock type bags and labeled for later use. This will preserve the fresh flavour of basil for up to four months.
For a large harvest, cut off as much as a half the plant at once.
Companion Planting
Will improve vigour and flavour of tomatoes, planted side-by-side. Also good with asparagus, oregano, and peppers. Basil helps repel flies, mosquitoes, and thrips.
More on Companion Planting.