Buying Plants: You can easily start basil plants from seed, but I’m not patient enough to wait so long to harvest the leaves. You can find basil starter plants practically anywhere these days, including your local grocery market. I have found the best plants with the lower chance of problems are ones from the local farmers markets. The plants are typically locally grown and you can ask the farmers how they have been treated.
Indoors/Outdoors: Fresh basil grows really well in both indoors and out. You can certainly choose to plant them directly in the ground, but I opt to use large containers so I can control the growth. My indoor plants seem to stay more compact with smaller leaves. This is perfect of quick clippings for garnishes or boosts of flavor in small doses. My outdoor plants end up with large bushy leaves which are perfect for harvesting in bulk for pesto or recipes that require large quantities.
Light: Basil requires full sunlight to flourish. I place my indoor pots in the sunniest part of my kitchen where I can conveniently snip the leaves as needed. My outdoor posts are located on the side of the house that gets at least 6 hours of sunlight. In my case, that happens to be my front entrance which now has a welcoming aroma when I come home.
Pests: Aphids are the post common problem for basil. You can tell if aphids are present when the plant looks wilted no matter how much water you give it. Also, there will be white specks around the base of the plant and under the leaves. I recently discovered a couple of my plants had caterpillars feeding off of the leaves. Also, according to cbsop on Twitter, slugs and snails “love” basil. Not a good thing.
Keep an eye out for pests and be sure to catch them early. One time I left for a weeklong trip to return home with an entire pot of basil destroyed from pests. Make sure to select a food safe and eco-friendly spray. Also, ALWAYS rinse your leaves before consuming.
Harvesting: I pick single leaves all the time for quick garnishes. But when I’m harvesting whole stems, I cut just above a joint in the plant where two stems are starting to grow. This step helps the plant to grow bushier, thus creating even more leaves.
Be careful to not allow your plant to grow buds or flowers. That means the basil is ready to go to seed and causes the leaves to become bitter. Clip the buds as soon as you see them.