If you’re tempted to toss a handful of fertilizer at your basil plant in hopes of creating a full, healthy plant, stop and think first. You may be doing more harm than good. Basil plant feeding requires a light touch; too much fertilizer may create a big, beautiful plant, but the quality will be badly compromised, as fertilizer decreases the all-important oils that give this herb its distinctive flavor and aroma.
Fertilizing Basil Plants
If your soil is rich, your plants may do just fine with no fertilizer at all, or you can dig an inch or two (2.5 to 5 cm.) of compost or rotted animal manure into the top 6 to 8 inches (15 to 20.5 cm.) at planting time.
If you think the plants need a little extra help, you can use a very light application of a dry fertilizer once or twice during the growing season. The best fertilizer for basil is any good quality, balanced fertilizer.
If you’re wondering when to feed basil growing in containers, the answer is once every four to six weeks for indoor plants and every two to three weeks for basil in outdoor pots. Instead of a dry fertilizer, use a water-soluble fertilizer mixed at half strength.
You can also use an organic fertilizer such as fish emulsion or liquid seaweed. Mix and apply the fertilizer according to label recommendations.
How to Fertilize Basil
To feed in-ground basil using a dry fertilizer, sprinkle the fertilizer lightly on the soil around the plants, then scratch the granules into the soil with a spade or garden fork. Be careful not to get the dry fertilizer on the leaves; if you do, rinse it immediately to prevent burning.
Water the plant deeply to prevent damage to the roots and to distribute the fertilizer evenly throughout the root zone.
For containerized basil plants, simply pour the diluted, water-soluble fertilizer onto the soil at the base of the plant.