Plant spacing: 15–30 cm (10–15 plants/m2)
Germination time and temperature: 8–10 days; 20–25 °C
Growth time: 20–30 days after transplant
Temperature: 15–25 °C
Light exposure: full sun; partial shade at > 25 °C
Plant height and width: 30–60 cm; 30–40 cm
Recommended aquaponic method: media beds, NFT and DWC
Growing parsley in aquaponic units: Parsley is a very common herb grown in both domestic and commercial aquaponic units owing to its nutritional content (rich in vitamins A and C, calcium and iron) and its high market value. Parsley is an easy herb to grow as the nutrient requirements are relatively low compared with other vegetables.
Growing conditions: Parsley is a biennial herb but it is traditionally grown as an annual; most varieties will grow over a two-year period if the winter season is mild with minimal to moderate frost. Although the plant can resist temperatures of 0 °C, the minimum temperature for growth is 8 °C. In the first year, the plants produce leaves while in the second the plants will begin sending up flower stalks for seed production. Parsley enjoys full sun for up to eight hours a day. Partial shading is required for temperatures > 25 °C.
Growing instructions: The main difficulty when growing parsley is the initial germination, which can take 2–5 weeks, depending on how fresh the seeds are. To accelerate germination, seeds can be soaked in warm water (20–23 °C) for 24–48 hours to soften the seed husks. Afterwards, drain the water and sow the seeds into propagations trays. Emerging seedlings will have the appearance of grass, with two narrow seed leaves opposite each other. After 5–6 weeks, transplant the seedlings into the aquaponic unit during early spring.
Harvesting: Harvesting begins once the individual stalks of the plant are at least 15 cm long. Harvest the outer stems from the plant first as this will encourage growth throughout the season. If only the top leaves are cut, the stalks will remain and the plant will be less productive. Parsley dries and freezes well. If dried, plants can be crushed by hand and stored in an airtight container.