What Kind of Fertilizers Can I Use to Grow Sweet Basil?

At Planting Time

• If you're starting sweet basil from seeds, incorporate a 16-16-8 all-purpose fertilizer into the top 6 to 8 inches of soil according to the manufacturer recommendations. Adding fertilizer to the soil before planting ensures your basil seeds have enough nutrients to sprout and establish a strong root system. If you're starting basil from transplants, add a liquid seaweed or kelp fertilizer to add trace mineral nutrients and a fertilizer especially designed for stimulating root growth, such as composted fruit or bone meal, to the planting hole.

Side-Dressing

• Fertilize outdoor sweet basil with an all-purpose 5-10-5 commercial fertilizer one or two times during the growing season. You only need about 3 ounces of fertilizer for every 10 foot row of basil plants. Fertilize indoor basil plants every four to six weeks and outdoor container plants every three to four weeks with an all-purpose liquid fertilizer at half strength. Once you begin to harvest your basil leaves by pinching them back, support new leaf growth by adding extra nitrogen in the form of fish emulsion, blood or alfalfa meal or manure every two to three weeks.

Fertilizer Recommendations

• When selecting a fertilizer for your sweet basil plants, look for slow-release varieties made from natural ingredients, such as compost or worm-casting teas. Quick-release fertilizers containing artificial ingredients will stimulate rapid leaf growth in your basil plants, but the resulting leaves may be less flavorful and the plant weaker.

Warning

• Over-fertilizing basil can reduce the fragrant oils in the leaves that give the herb its flavor. Fertilizing basil too heavily also makes your plants more susceptible to pests and disease, so it's better to er on the lighter side. Apply fertilizers when it's cool outside, preferably lower than 60 degrees Fahrenheit, to prevent fungal or bacterial leaf wilts. Always rinse your basil leaves with water after fertilizing, as the leaves can burn if exposed to some fertilizers. Always follow the fertilizer package directions carefully, and keep the packages in a cool, dry place out of reach of children and pets.