Tips for Productive Basil
Start basil seeds indoors 6 to 8 weeks before the last frost. Use a well-drained soilless media in small pots. Basils require darkness for proper germination, so cover the seeds lightly with soil or vermiculite, at least 1/8 inch.
Invest in a heat mat to maintain soil temperatures at 65 degrees. This will ensure faster and more even germination, less damping off, and strong seed development. Basil requires sunlight, so make sure to have a sunny window or a proper grow light.
Some basils, such as Genovese basil, are quick to germinate, often in 5 to 7 days. Tulsi basil, Ocimum tenuiflorum, is very slow to germinate and requires warmer temperatures and more light to develop strong plants. Even with heat mats and additional lighting, germination often takes 14 days, and plant development is much slower. Be patient and allow soil temperatures to warm up to at least 65 degrees before transplanting. Purple and dark-leaved basils also take longer to germinate.
Basils are big feeders and need more fertilizing than perennial herbs. If you are growing basil in containers, supply both a slow-release fertilizer when you first plant, as well as liquid fertilizers every 1 to 2 weeks, depending on the pot size and how often you need to water. If growing in the ground, incorporate compost and a slow-release fertilizer at planting, and apply liquid fertilizer every 2 to 3 weeks to maintain healthy plant growth. Organic dry fertilizers and fish emulsion are preferred. This may seem extreme, especially since with perennial herbs such as oregano and rosemary, you may only fertilize once a year! Think of basil as a hungry teenager, and if it doesn't get enough nitrogen and water, it wants to send up pretty flowers, get pregnant, have babies, and get old. Your job is to keep it young and in school, so you can make lots of delicious food and drinks with it.
To keep basil in a vegetative state, pinch back blooms and several sets of leaves. If the plants try to rebloom quickly, it is a sign that it's time to fertilize! Don't forget to eat the flowers! All culinary herb flowers are edible, and basil flowers are robust and a bit sweet.
Plant basil in succession to get the highest quality flavor throughout the season. This is especially true in more temperate climates, where the basil growing season may be as long as March through October. March-planted basil will not produce good quality leaves by October, but June-planted basil will still be vigorous for fall harvest.
If you plan to save seeds, remember that basil varieties, and even between species, will cross-pollinate readily. Only allow one type of basil to bloom and set seed at a time to ensure that you are saving each variety separately.
All basils will readily produce roots from cut tips, either in water or in a soilless media.
Check out our YouTube video on basil varieties and growing basils!