How Often Do You Fertilize Parsley?

Garden Parsley Plants

• Parsley plants started and grown outside have minimal fertilization needs. During their growing season, such parsley plants require only one or two fertilizing sessions. Use a commercial 5-10-5 fertilizer, meaning it contains 5 percent nitrogen, 10 percent phosphorus and 5 percent potassium. Deposit 10 oz. of fertilizer for every 10-foot-long row of parsley plants. Also, spread mulch made from grass and leaves around the parsley to infuse the soil with extra nutrients and help the plants retain moisture.

Container Parsley

• Parsley can also be grown exclusively in containers, but it has different fertilizer needs than that grown directly in the soil. To keep parsley healthy in containers, mix an organic fertilizer with the potting soil before adding the parsley seeds. If the parsley plants begin to look weak or sickly, treat them with a dose of fish emulsion at half of the suggested strength printed on the packaging, once every few weeks.

Parsley Transplants

• It's possible to start growing parsley plants indoors, where they can be protected from the elements while they're still young and vulnerable. However, when parsley is transplanted into an outdoor garden, its fertilizer needs change. For parsley started in a container and then placed directly into the soil, the University of Minnesota advises using a 5-10-5 fertilizer at half the strength suggested on the label. Apply the fertilizer once every three to four weeks.

Extra Boosts of Fertilizer

• To keep parsley plants healthy and strong, they sometimes need an extra dose of fertilizer. If parsley is grown in poor quality soil, give the plants a monthly spritz of liquid fertilizer from a spray bottle. Also, a slow-acting granular fertilizer, blended into the soil, will release nutrients throughout the growing season. However, before eating parsley, wash it well to remove all fertilizer residue, which may be toxic.